567 open-source projects for the open internet, grouped by kind and usage.
Pre-ActivityPub federated activity-feed format from the OpenSocial era. JSON-based, simpler than AS2; informally influenced Atom and seeded what later became ActivityPub.
Open protocol for decentralized social networking. Powers various fediverse related projects such as Mastodon, PeerTube, Funkwhale and Pixelfed.
Homepage: https://atproto.com
Federated protocol developed by Bluesky for social applications. Combines portable DID-based identity, signed user repositories, and large-scale indexing relays; focused on social networking rather than filesystem semantics.
Open syndication formats that turn any website into a feed independent readers and aggregators can subscribe to. The original federation of the open web.
Decentralized Social Networking Protocol. Open specification for storing social graph and content as a public good on shared infrastructure rather than per-application silos.
Decentralized social protocol where identities live on Ethereum and message data is replicated across a network of hubs. Open source clients (e.g. Warpcast) and SDKs build on top.
Early Internet protocol for looking up information about a user on a remote system. Predecessor to WebFinger.
Generation-2 microformats with a simpler, more orthogonal syntax (h-card, e-content, p-name). The form actually used by the modern indieweb stack.
W3C protocol for creating posts on a user's own domain using third-party clients. Letting any client publish to any compliant server.
API spec separating reader UI from feed-aggregation backend. Lets you swap reader clients while keeping your subscriptions/timeline server-side.
Successor to Zot6 used by Streams. Continues the nomadic-identity tradition with simpler crypto and improved ActivityPub compatibility.
Notes and Other Stuff Transmitted by Relays β a simple protocol where clients sign events with a public key and publish them to multiple relays. Identity is the keypair, not an account on any server.
Google-led API for building social applications across multiple social networks. Adopted by Orkut, MySpace, hi5, LinkedIn. Stewardship moved to W3C Social Web WG in 2014.
Outline Processor Markup Language β XML format for nested outlines. Practically used as the lingua franca for subscription lists between RSS readers.
Predecessor to ActivityPub β a bundle of older standards (Atom, PubSubHubbub, Salmon, WebFinger) that powered the first wave of federated microblogging.
Early XML-RPC mechanism for cross-blog notifications. Predecessor to Webmentions.
Push-based extension to Atom and RSS β publishers ping a hub, the hub fans out updates to subscribers in real time. Standardized as WebSub by the W3C in 2018.
RelayNet β federated BBS message network primarily on PCBoard BBSes. Echomail-style topical conferences delivered between member BBSes nightly.
Federated comments and replies on Atom/RSS feeds. Pushed back upstream to where the original post was published. Replaced by ActivityPub's inbox model but conceptually identical.
Peer-to-peer gossip protocol where each user has an append-only signed log. Replication is opportunistic over local network, internet peers, and "pubs," making it well-suited to offline-first social use.
Decentralized social protocol where each user runs (or rents) their own Tent server and owns their data. Defunct after 2015.
W3C recommendation for cross-site notifications. Lets a site tell another site it has been linked, enabling decentralized comments, likes, and reposts.
Linked rings of independent sites β each site links to the next-in-ring and the previous, with a central "hub" page listing members. Pre-Google discovery infrastructure. Sage Weil's WebRing.com formalized the model; the concept lives on as a small-web revival.
W3C standardization of PubSubHubbub β federated publish/subscribe over HTTP for feeds. The push layer under ActivityPub-adjacent feeds and many fediverse bridges.
Federated BBS network for the WWIV BBS software (Wayne Bell's "World War IV"). Smaller than FidoNet but technically distinct routing.
Federation protocol behind Friendica and Hubzilla. Pioneered "nomadic identity" β your identity isn't tied to one server, you can clone yourself across instances and channels survive server moves.
Successor to Zot used by current Hubzilla. Refined HTTP-signature-based delivery and stricter conversation threading.
DNS-based Authentication of Named Entities (RFC 6698). Publish TLS certificate fingerprints in DNS records signed by DNSSEC; an alternative to the PKI cert authority model. Notably used by SMTP MTA-STS replacement and some PGP keyservers.
W3C Decentralized Identifiers β a URI scheme for identifiers controlled by their owner rather than registered with a central authority.
Signed-zone extensions for DNS. Provides cryptographic authenticity (not confidentiality) for DNS responses. Slow adoption but powers DANE, RPKI bridges, and modern DNS-based identity hacks.
FIDO Alliance + W3C's framework for passwordless auth: CTAP2 (authenticator-to-client transport) + WebAuthn (browser API). The plumbing underneath modern hardware-key login and Passkeys.
Early Internet protocol for looking up information about a user on a remote system. Predecessor to WebFinger.
Decentralized authentication using your own domain as identity. Part of the IndieWeb stack.
Successor to Zot6 used by Streams. Continues the nomadic-identity tradition with simpler crypto and improved ActivityPub compatibility.
Open standard for delegated authorization. Foundation for OpenID Connect, IndieAuth, and most modern federated auth flows.
Original decentralized identity standard β users proved ownership of a URL to sign in to any participating site. Superseded by OpenID Connect.
Federated identity layer on top of OAuth 2.0. Lets any site sign users in via an independently operated identity provider.
Scalable timestamping protocol that anchors arbitrary hashes to the Bitcoin blockchain via aggregation, proving data existed at a point in time.
Consumer-facing branding for syncable WebAuthn credentials. Built on the same FIDO2/WebAuthn primitives but adds cross-device portability via vendor keychains (iCloud Keychain, Google Password Manager, 1Password). Announced jointly by Apple/Google/Microsoft + the FIDO Alliance in 2022.
Mozilla's browser-mediated identity protocol (originally BrowserID). Identity rooted in an email address; any email provider could become a Verified Email Provider and act as IdP, with Mozilla running a fallback bridge for providers that hadn't yet. Designed as a simpler, privacy-preserving alternative to OpenID. Shut down November 2016 after weak uptake.
Pretty Good Privacy β cryptographic system for email encryption, signatures, and web-of-trust identity. OpenPGP formalized in RFC 4880.
Security Assertion Markup Language β XML-based protocol for cross-organization SSO. IdP signs an assertion about the user; SP verifies and lets them in. Backbone of academic federations (eduGAIN, InCommon) and enterprise SSO providers (Okta, Auth0, Ping). SAML 2.0 (2005) is the dominant version.
Smart contract and identity layer anchored to Bitcoin. Originally Blockstack (2017), pivoted to a full L1 with Clarity contracts and BNS naming.
Electronic-business-card format. Powers every "contact card" you've shared as a .vcf file; the data model under CardDAV.
W3C Web Authentication API β browser-mediated public-key authentication against any relying party. Together with the FIDO2 CTAP transport, lets a user-held authenticator (hardware key, platform biometric, or synced credential) sign challenges per-site, eliminating shared secrets. Reached W3C Recommendation in 2019.
Lookup protocol for finding metadata about a resource by email-style address. The discovery layer used by ActivityPub, Matrix, and others.
Federation protocol behind Friendica and Hubzilla. Pioneered "nomadic identity" β your identity isn't tied to one server, you can clone yourself across instances and channels survive server moves.
Successor to Zot used by current Hubzilla. Refined HTTP-signature-based delivery and stricter conversation threading.
Peer-to-peer messaging protocol with broadcast-style delivery: every node receives every message, so observers can't tell which was meant for which recipient.
The original federated messaging system of the internet. Independently operated mail servers exchange messages over SMTP using DNS-based addressing.
Inter-Asterisk eXchange Protocol β single-port VoIP signaling-plus-media protocol designed for PBX trunking. Federation-friendly (NAT-tolerant, runs on UDP/4569) and the canonical alternative to SIP between Asterisk-family servers. Standardized as RFC 5456 in 2010.
Mail retrieval protocol that keeps messages on the server, supporting folders, flags, partial fetches, and multi-device sync. Dominant client-to-server protocol for email today.
Internet Relay Chat β a 1988 federated text chat protocol. Networks like Libera.Chat consist of multiple independently operated servers that share channels and users.
Modern JSON-over-HTTP replacement for IMAP, designed by Fastmail. Batched requests, push notifications, and a generic data-sync model that extends beyond mail to calendars and contacts.
Homepage: https://matrix.org
Open protocol for decentralized, federated real-time communication. Provides end-to-end encryption via the Olm/Megolm ratchets (not MLS) and supports messaging, VoIP, and file sharing across independently operated homeservers.
Type-II anonymous remailer. Messages travel through a chain of operator-run nodes, each peeling one layer of encryption, to deliver mail untraceably.
Type-III anonymous remailer protocol. Successor to Mixmaster with replay prevention, directory servers, and forward-secure exit replies.
XMPP extension providing multi-end, multi-device end-to-end encryption based on the Signal Protocol's Double Ratchet.
Off-the-Record Messaging β protocol layered on top of instant-messaging transports (XMPP, AIM, etc.) providing end-to-end encryption with perfect forward secrecy and message deniability. The Signal Protocol's Double Ratchet directly descends from OTR's design.
Download-and-delete mail retrieval protocol. Simpler than IMAP and well-suited to single-device, offline-first mail clients; still widely supported but largely replaced by IMAP and JMAP.
MIT/EPFL anonymity system (PETS 2016) combining verifiable shuffles with private information retrieval. Provides anonymity even when most servers in the anonymity set are malicious, with bandwidth costs an order of magnitude better than prior strong-anonymity systems. Research prototype, no deployed implementation.
RelayNet β federated BBS message network primarily on PCBoard BBSes. Echomail-style topical conferences delivered between member BBSes nightly.
Session Initiation Protocol β the IETF standard for federated voice, video, and messaging session setup. Underpins most interoperable VoIP between independent providers.
Server-to-server mail transport protocol. The federation layer of email: STARTTLS for transport encryption (now near-universal), MX records for routing, SPF/DKIM/DMARC bolted on for spam and forgery resistance.
End-to-end encrypted SMS and messaging app from Whisper Systems. Merged with RedPhone into Signal in 2015.
MIT messaging system (SOSP 2015) with cryptographic dead-drops plus differential-privacy-style noise. Hides not just message content but the social graph and conversation patterns β what observers learn about who's talking to whom is statistically bounded. Influenced Stadium and Karaoke follow-ups; not deployed.
Defunct peer-to-peer messaging protocol that ran on Ethereum's devp2p network. Deprecated in favor of Waku.
Federated BBS network for the WWIV BBS software (Wayne Bell's "World War IV"). Smaller than FidoNet but technically distinct routing.
Calendar Sync via WebDAV (RFC 4791). The federated standard for calendar sync β every modern calendar app talks it.
Pre-CalDAV WebDAV extension for group calendar/contacts data. Largely superseded by CalDAV+CardDAV; some legacy Kolab/Citadel deployments still implement it.
iCalendar (RFC 5545) β the data format under .ics files, calendar invites, and CalDAV. Every calendar event in the world has been an iCalendar VEVENT at some point.
Open Mobile Alliance Data Synchronization (formerly SyncML) β the federated sync protocol for early-2000s mobile phones to sync contacts/calendars with desktop or carrier servers.
Electronic-business-card format. Powers every "contact card" you've shared as a .vcf file; the data model under CardDAV.
W3C standard suite for layered annotations on any web content (Data Model + Protocol + Vocabulary, all 2017 Recommendations). Annotations are JSON-LD documents with selectors that target arbitrary URL-addressable resources; the protocol defines how to serve, fetch, and federate annotation collections. Hypothes.is is the dominant deployment; the open-source Hypothesis server is self-hostable.
Advanced Direct Connect β cleaner, extensible successor to NMDC. Adds TLS, BASE32 IDs, command extensions, and content-addressed file hashes.
Federated network filesystem from CMU's Andrew Project. Cell-based namespace lets independently administered sites federate into a global /afs/<cell>/... tree; Kerberos auth, location-transparent paths, aggressive client-side caching. The historical model FedFS later tried (and failed) to retrofit onto NFSv4. Still maintained as OpenAFS.
Decentralized storage protocol aimed at permanent data β a one-time upload fee endows nodes to host the data indefinitely. Backed by a blockweave structure rather than a linear chain.
Decentralized digital currency on a proof-of-work blockchain. The original cryptocurrency; foundational to many later distributed systems.
Original peer-to-peer file distribution protocol. Files are split into pieces and exchanged among swarms of downloaders; popular content gets faster as more peers join.
Decentralized data network for mutable, composable documents anchored to blockchains. Built around streams of signed commits managed by the Ceramic node software.
Cooperative File System: read-only p2p filesystem on the Chord DHT (SOSP 2001). Blocks content-addressed, replication via DHT successor lists, root signed by publisher. Defined the template for IPFS-style designs five years before IPFS.
Federated network filesystem descended from AFS-2. Adds disconnected operation (write while offline, reintegrate later), optimistic replication, and weak-consistency conflict handling. Open source, still nominally maintained; the canonical "AFS plus mobile".
Homepage: https://dat-ecosystem.org
Original peer-to-peer data sharing protocol built on append-only logs. Largely succeeded by the Hypercore Protocol, but the Dat ecosystem continues to maintain related tooling for versioned, distributed datasets.
David Chaum's original blinded-signature electronic cash (paper 1983; DigiCash company 1989). Anonymous digital cash issued by a bank; bankruptcy in 1998 killed the company but the cryptography became the foundation of every digital-cash design after.
Hub-based p2p file-sharing protocol (NMDC). Each hub is operator-run; clients connect to one or many hubs to chat and share files. Open clients (DC++, Valknut) implement it; original NeoModus client is defunct.
Homepage: https://earthstar-project.org
Distributed, offline-first database for small, cozy networks of people. Provides shared key-value "shares" with cryptographic identities; recent versions are built on the Willow Protocol.
Server-indexed p2p file sharing network with content-hash addressing (ed2k:// URIs). Successor to Napster, contemporary of Gnutella; the original eDonkey servers were shut down but Kad clients (aMule, eMule) still run.
Programmable smart-contract blockchain. Substrate for many distributed app systems including ENS, Status, DSNP, Farcaster, and Swarm.
Incentive layer for IPFS-style storage. Miners commit to storing client data for a fixed term and prove they're doing so via proofs-of-spacetime, paid in FIL.
Homepage: https://freenetproject.org
Peer-to-peer platform for censorship-resistant, decentralized storage and communication. Data is encrypted and distributed across nodes; participants do not know what content their node hosts.
One of the oldest Internet protocols, for transferring files between client and server. Separate control and data channels; cleartext by default. Largely displaced by HTTPS, SFTP, and rsync but still in use.
Early decentralized peer-to-peer file-sharing protocol using query flooding. Influenced BitTorrent, YaCy, and many later P2P systems.
Homepage: https://holepunch.to / https://github.com/holepunchto/hypercore
Peer-to-peer append-only log with cryptographic integrity and sparse replication. Forms the foundation of the Hypercore Protocol (formerly Dat) for building distributed apps and filesystems like Hyperdrive.
POSIX-like peer-to-peer filesystem built on Hypercore. Versioned, sparse, and replicates over Hyperswarm.
Routing protocol for payments across ledgers (any ledger β bank, crypto, mobile money). Treats value transfer the way IP treats packets: best-effort, hop-by-hop.
Homepage: https://ipfs.tech
Content-addressed, peer-to-peer hypermedia protocol. Files are identified by cryptographic hashes (CIDs) and retrieved from any peer holding the content. Not end-to-end encrypted by default; uses a different federation model than MLS-based systems.
Data model for content-addressed linked data β the substrate beneath IPFS, Filecoin, and other content-addressed systems. Defines how typed data structures hash, link, and traverse.
Read-write peer-to-peer filesystem on top of DHash/Chord (OSDI 2002). Each writer maintains an append-only log; readers merge logs across participants to reconstruct a coherent view. Early demonstration that a DHT-backed FS could support mutation without a central authority.
Cross-platform file transfer and terminal-emulator protocol from Columbia. Worked over serial lines, modems, and TCP/IP; cross-OS interop was the killer feature.
Payment channels over Bitcoin enabling near-instant, low-fee transactions. Open peer-to-peer mesh of channels; LND, c-lightning, Eclair are the major implementations.
Federated Bitcoin sidechain run by an Elements-based consortium ("functionaries"). Confidential transactions, faster settlement, native asset issuance. Code (Elements) is open; consortium operates the chain.
Decentralized metadata layer for digital media β image attribution, provenance, licensing β built on IPFS and IPLD. Acquired by Spotify in 2017 and discontinued.
Early commercial peer-to-peer file storage system with a micropayment-based bandwidth/storage market. Direct ancestor of Tahoe-LAFS.
Privacy-focused cryptocurrency. Ring signatures, RingCT confidential amounts, stealth addresses. The most widely-used cryptocurrency that actually delivers transactional privacy.
The original peer-to-peer music sharing network. Centralized index served file lookup; transfers happened directly between peers. Sued out of existence in 2001 but defined the p2p era that followed.
Federated metadata harvesting protocol for digital archives. Data providers expose Dublin Core records over HTTP; service providers (search engines, aggregators, libraries) periodically harvest them. The backbone of institutional repository discoverability β every DSpace, EPrints, and Fedora repo speaks it.
Research vision for a global persistent data utility across untrusted servers: erasure coding for durability, Byzantine agreement for consistency, content-based routing via Tapestry. Never shipped at scale; the Pond prototype demonstrated the model and shaped a generation of p2p storage research.
Persistent p2p storage layer on the Pastry DHT (SOSP 2001). Immutable file-IDs, k-replica placement on nearest live nodes, smart-card-backed quota. Companion to Microsoft Research / Rice's broader work on structured overlays.
Open protocol for personal-data storage β apps connect to a user's chosen storage server (their own or a provider) over a simple HTTP API.
Federated consensus protocol for the XRP Ledger and predecessor RipplePay. Validator nodes vote; trust list is per-node. Open code (rippled), commercial steward (Ripple Labs).
Wide-area peer replication system, descendant of UCLA's Ficus and Rumor filesystems. Peer-to-peer optimistic replication organized into "wards" of mutually-interested nodes; designed for mobile users syncing across the internet. Research code, never widely deployed.
Autonomous, decentralized data network from MaidSafe. Stores encrypted, self-authenticating chunks distributed across community-run nodes paid in network tokens.
Global federated filesystem where the server's public-key hash is part of the path (/sfs/server.example.com:KEYHASH/...). Eliminates the need for a trusted PKI β any server on the internet can publish a namespace, any client can verify it. Deeply influenced IPFS, Tahoe-LAFS, and content addressing more broadly.
File transfer and management protocol layered on top of SSH. Unrelated to FTP despite the name β provides a secure, authenticated channel using the SSH transport.
Decentralized cloud storage marketplace. Renters and hosts agree to storage contracts on the Sia blockchain, with files encrypted and erasure-coded across many hosts.
Stellar Consensus Protocol β federated Byzantine agreement across user-chosen quorum slices. Designed for cross-border payments without proof-of-work or proof-of-stake.
Decentralized object storage network. Files are encrypted client-side, erasure-coded, and distributed across independently operated storage nodes; access is paid in STORJ tokens.
Decentralized storage and communication layer in the Ethereum stack. Chunks are content-addressed and replicated across nodes, with incentives settled via the BZZ token.
Minimal UDP-based file transfer protocol with no authentication. Used mostly for network boot (PXE), firmware loading, and diskless workstation provisioning on local networks.
Open HTTP-based resumable upload protocol. Solves the "giant file upload failing at 99%" problem; libraries and clients across most languages.
Federated personal-data namespace. Paths look like ann@example.com/photos/...; each user picks their server, public-key identity, end-to-end encryption with signed-wrap key sharing across users. Hibernated rather than dead β reference servers and Go client remain on GitHub.
HTTP extension for collaborative authoring and remote filesystem operations. The interop layer for ownCloud, Nextcloud, Apple Calendar/Contacts (CalDAV/CardDAV), and many corporate file shares.
BitTorrent over WebRTC, runnable in the browser. Lets web pages distribute files peer-to-peer without plugins.
Homepage: https://willowprotocol.org
Specification for synchronizable, authenticated key-value stores. Provides fine-grained capability-based access control and efficient set reconciliation between peers.
Homepage: https://github.com/wnfs-wg
Encrypted, content-addressed filesystem built on IPLD/IPFS. The private filesystem uses a skip-ratchet to derive per-write keys, giving O(log n) random access to history while letting writers rotate keys forward without re-encrypting past data. Capability-based access control via UCANs; public and private subtrees coexist under one namespace.
zk-SNARK-based privacy cryptocurrency. Optional shielded transactions; pioneered the zero-knowledge proof systems now ubiquitous in blockchain privacy work.
Federated metadata harvesting protocol for digital archives. Data providers expose Dublin Core records over HTTP; service providers (search engines, aggregators, libraries) periodically harvest them. The backbone of institutional repository discoverability β every DSpace, EPrints, and Fedora repo speaks it.
XML format for describing a search engine's URL template and metadata, so browsers can offer it as an installable search source. The thing behind "Add this site as a search engine" in Firefox/Edge.
Search/Retrieve via URL β Library of Congress's HTTP-based modernization of Z39.50. Queries are CQL (Contextual Query Language), responses are XML; the companion CQL specification gives a sensible grammar where Z39.50's RPN was painful. Most library systems support SRU alongside legacy Z39.50.
Wide Area Information Server. Early-1990s clientβserver protocol for searching and retrieving full-text documents across distributed servers. Largely superseded by the Web, but open-source implementations (freeWAIS, freeWAIS-sf) influenced later distributed search systems.
ANSI/NISO Z39.50 (also ISO 23950): binary client/server protocol for searching and retrieving records from remote databases. Predates the web and is still the lingua franca of library catalog interop β every union catalog, OPAC, and bibliographic utility speaks it. Maintained by the Library of Congress as the protocol's Maintenance Agency.
Better Approach To Mobile Adhoc Networking β Advanced. Layer-2 mesh routing in the Linux kernel, presenting the mesh as a transparent virtual switch. Used by Freifunk and most community Wi-Fi networks; complements OLSR's layer-3 routing approach.
Loop-avoiding distance-vector routing protocol designed for both wired and wireless networks (RFC 8966, originally RFC 6126). Used in community meshes, Cjdns/Yggdrasil-adjacent deployments, and as the IPv6 routing daemon in homenet setups.
Encrypted mesh networking protocol with cryptographic IPv6 addresses derived from public keys. Foundation of the Hyperboria experimental network.
High-speed Onion Routing at the Network Layer (USENIX Security 2015). Onion-routing built into the network layer rather than as an overlay, with per-hop state encoded in the packet header β designed for line-rate anonymous routing at ISP scale. Influential design, no production deployment.
Invisible Internet Project β an anonymous overlay network using garlic-routed tunnels. Designed primarily for hidden services ("eepsites") inside the network rather than browsing the open web.
Distributed hash table using XOR distance over node IDs. The substrate under BitTorrent's Mainline DHT, IPFS, libp2p, ethereum discovery, and most modern p2p systems.
Onion-routed network using the Oxen service-node infrastructure. An alternative to Tor with different incentive and routing tradeoffs.
Mix network design from UCL (USENIX Security 2017). Continuous-time Poisson mixing rather than batched flushes β every packet experiences an independent exponential delay, providing strong anonymity at controllable latency cost. Foundation for Nym's mainnet.
Open source mesh networking and messaging over LoRa radios. Forms self-organizing off-grid networks for text messaging, telemetry, and location sharing.
Mesh overlay network built around a private certificate authority and lighthouse coordinators. Originally from Slack.
Network Time Protocol β federated, stratum-based clock sync that has kept the internet's clocks aligned since 1985. NTS extension adds authentication.
Production mixnet built on the Loopix design. Sphinx-encrypted packets traverse a network of mixnodes with Poisson-distributed delays; cover traffic obscures real flows. Live mainnet incentivized by the NYM token; targeting low-bandwidth metadata-private messaging and VPN-style usage.
Optimized Link State Routing Protocol (RFC 3626). Proactive link-state routing for mobile ad-hoc networks; uses multipoint relays to reduce flooding overhead. Widely deployed in community mesh networks (Freifunk, Funkfeuer, Athens Wireless) before B.A.T.M.A.N. took over.
Anonymous routing design presented at DEF CON 16. Anonymous IP-over-encrypted-tunnels protocol; mostly theoretical, never widely deployed.
Microsoft's remote desktop protocol β graphical session sharing with channel multiplexing for audio, clipboard, and device redirection. Open-sourced clients (FreeRDP, Remmina) exist for non-Windows platforms.
Encrypted, networking-stack-agnostic mesh protocol for resilient communication over LoRa, packet radio, TCP/IP, and more.
MIT/EPFL anonymity system (PETS 2016) combining verifiable shuffles with private information retrieval. Provides anonymity even when most servers in the anonymity set are malicious, with bandwidth costs an order of magnitude better than prior strong-anonymity systems. Research prototype, no deployed implementation.
Cryptographically authenticated time protocol from Google's Adam Langley. Detects malicious servers by cross-checking signed responses against multiple peers.
Encrypted, authenticated remote-shell and tunnel protocol. Public-key auth, port forwarding, and the substrate for SFTP/SCP and Git over SSH.
JSON+UDP DHT protocol for end-to-end encrypted messaging between any two endpoints. Influenced later p2p stacks; never reached production traction.
One of the original ARPANET protocols: a cleartext remote terminal over TCP. Long obsolete for shell access (replaced by SSH) but still used for protocol probing, MUDs, and BBS-style services.
Anonymity overlay network of volunteer-run relays. Routes traffic through encrypted multi-hop circuits and hosts onion services that are reachable without revealing their location.
Cross-platform remote framebuffer protocol (RFB). Simpler and more portable than RDP; the basis for screen sharing in macOS, Linux remote desktops, and tools like noVNC.
Browser-native real-time audio, video, and data channels between peers. NAT traversal via ICE/STUN/TURN; mandatory DTLS-SRTP encryption. The transport substrate for most modern p2p web apps.
Full-duplex communication channel over a single TCP connection, upgraded from HTTP. Enabled real-time browser apps before WebRTC and remains the default for live data feeds.
Modern open-source VPN protocol designed for simplicity and performance. Foundation for Tailscale/Headscale, Nebula, and many other overlay networks.
End-to-end encrypted IPv6 mesh overlay. Self-organizes peers into a spanning tree to provide a flat, globally-routable address space without any central allocation.
Decentralized web platform using Bitcoin cryptography for identity and BitTorrent for content distribution. Sites are addressed by public keys and served peer-to-peer by visitors.
DNS-based Authentication of Named Entities (RFC 6698). Publish TLS certificate fingerprints in DNS records signed by DNSSEC; an alternative to the PKI cert authority model. Notably used by SMTP MTA-STS replacement and some PGP keyservers.
Domain Name System β the hierarchical, federated naming system that maps human-readable names to internet resources. Operated as a globally distributed tree of independent authoritative servers.
RFC 8484. DNS queries tunneled over HTTPS. Privacy from ISP-level snooping; bypasses censoring resolvers. Default for Firefox in many regions.
RFC 7858. DNS over TLS rather than over HTTPS. Cleaner separation from web traffic, supported by Android Private DNS and Unbound/Knot/Stubby resolvers.
Encrypted-and-authenticated DNS protocol predating DoH/DoT. Still used by OpenDNS/Quad9/AdGuard and projects like dnscrypt-proxy.
Signed-zone extensions for DNS. Provides cryptographic authenticity (not confidentiality) for DNS responses. Slow adoption but powers DANE, RPKI bridges, and modern DNS-based identity hacks.
Ethereum Name Service β decentralized naming on Ethereum smart contracts, mapping human-readable names like alice.eth to addresses and resources.
GNU Name System β petname-based, censorship-resistant naming on GNUnet. Each user maintains their own zone and delegates trust explicitly.
Blockchain-based decentralized naming system for top-level domains. Aims to replace the ICANN root with cryptographic ownership.
DNS over link-local multicast β resolve .local names without a server. Used together with DNS-SD for zero-config service discovery on a LAN.
Earliest blockchain-based decentralized name system. Pioneered the .bit TLD outside ICANN.
Alternative DNS root operated by volunteers. Resolves both ICANN TLDs and a set of community-managed TLDs outside the standard hierarchy.
Fifteen-element metadata vocabulary (title, creator, subject, date, β¦) that anchored OAI-PMH, repository metadata, and most cataloguing on the open web.
Friend of a Friend β RDF vocabulary for describing people and the relations between them. The semantic-web era's social-graph standard, pre-ActivityPub.
Lightweight application-layer protocol for hypertext, sitting between Gopher and HTTP in complexity. Mandatory TLS, line-oriented responses, and a "small internet" ethos; many independent servers and clients.
Pre-Web hierarchical document and menu protocol from 1991. Still has a small, actively maintained "gopherspace" of independently operated servers.
UDP-based small-web protocol that targets high-latency and lossy networks. Trades TCP/TLS overhead for reachability β designed with HF radio and low-power devices in mind.
Application-layer protocol that underpins the World Wide Web. Stateless request/response over TCP; TLS (HTTPS) is now the default. Federated across independently operated servers.
Pre-web hypertext system from TU Graz with bidirectional links, transclusion, and integrated search across a federated server network. Lost to HTTP/HTML's simpler model; some of its ideas resurface in IPFS and the indieweb.
JSON for Linked Data β RDF in JSON garb. The serialization Schema.org SEO data, Verifiable Credentials, and ActivityStreams 2.0 all use.
Vannevar Bush's 1945 conceptual hypertext system β microfilm-based, with associative "trails" between documents. Never built; conceptual ancestor of every hypertext system after.
Tiny gopher-like protocol stripped down further: no selectors, no item types, just path-to-bytes. One of several small-web experiments orbiting Gemini.
Convention for embedding structured data in HTML attributes (h-card, h-entry, etc.). Underpins the indieweb stack; the simplest semantic-web bet that actually shipped.
Smallest-possible small-web protocol: no headers, no metadata, no TLS, just send a path and get bytes back. A reaction to gemini's complexity.
Tim Berners-Lee's compact RDF syntax with rules. Ancestor of Turtle (which dropped the rule extension to focus on plain triples).
Original hypertext vision: bidirectional, visible, fine-grained links; transclusion; versioning; micropayments to original authors. Predates and outlasted the web in concept; never shipped at scale.
Resource Description Framework β the data model under the semantic web. Subject-predicate-object triples, IRIs as identifiers, schema via OWL/RDFS.
Resource Description Framework in Attributes β embeds RDF triples in HTML via custom attributes. Heavier than Microformats; used heavily in scholarly publishing and Schema.org.
Shared vocabulary for structured data on the web. Origin of the JSON-LD-or-microdata blobs in every modern website's
; powers Google/Bing rich results.Experimental small-web protocol with a richer document format than Gemini's gemtext, including inline styling and metadata. Niche but actively used by a handful of capsules.
Semantically Interlinked Online Communities β RDF vocabulary for describing online discussion (forums, blogs, comments). Influenced ActivityStreams.
SQL for RDF β query language for triplestores. SPARQL 1.1 added updates, federated queries, and aggregates. The query language behind Wikidata.
Even-simpler successor proposal to Gemini, dropping TLS and client identity in exchange for minimal implementation surface.
Companion upload protocol to Gemini. Same wire format and TLS requirements but adds the ability to write content to a server β used by Gemini wikis and pastebins.
Terse RDF Triple Language β human-readable RDF syntax that succeeded the noisier RDF/XML. The serialization most people writing RDF by hand use.
Virtual Reality Modeling Language β the 1990s attempt at a 3D web. Open standard, dropped into HTML pages over HTTP, succeeded by X3D. "Metaverse" 25 years ahead of the hype cycle.
W3C standard suite for layered annotations on any web content (Data Model + Protocol + Vocabulary, all 2017 Recommendations). Annotations are JSON-LD documents with selectors that target arbitrary URL-addressable resources; the protocol defines how to serve, fetch, and federate annotation collections. Hypothes.is is the dominant deployment; the open-source Hypothesis server is self-hostable.
Real-time collaborative editor and federated communication protocol. Originated as Google Wave (2009), donated to Apache in 2010, retired in 2018.
Homepage: https://automerge.org
CRDT library for building local-first applications with automatic merging of concurrent changes. Provides JSON-like data structures with cryptographic change history; covers merge semantics but not transport or storage.
Composable CRDT library for collaborative apps. Provides primitive CRDTs (counters, sets, lists, text) that compose into custom data types.
Framework for building local-first, peer-to-peer collaborative applications. Provides ECHO (data sync), HALO (identity), and MESH (networking).
Local-first sync layer for Postgres and SQLite. Replicates relational data to clients and syncs writes back through standard SQL semantics.
Local-first toolkit for collaborative apps β CoValues (CRDT-backed objects) sync between devices and peers through a Jazz cloud or your own server.
High-performance CRDT library for local-first apps. Aims to combine the ergonomics of Yjs/Automerge with better historical-version performance.
Peer-to-peer application runtime from Holepunch. Built on Hypercore, Hyperswarm, and Hyperdrive, it lets developers ship serverless apps that distribute and update themselves over P2P.
PHP framework implementing WebDAV, CalDAV, and CardDAV. Backbone of BaΓ―kal, ownCloud/Nextcloud's CalDAV+CardDAV layer, and many other PHP stacks.
Distributed object capability framework from the Spritely Institute. Provides secure, transactional actor-style programming across machines as a foundation for decentralized social networks.
Reactive in-memory data store for the browser with optional sync to CRDTs, IndexedDB, or remote databases. Local-first by default.
Homepage: https://yjs.dev
High-performance CRDT framework for shared editing of structured data. Supports rich text, arrays, and maps with pluggable network and persistence providers; widely used for real-time collaboration in editors.
SQLite extension that adds CRDT semantics β multi-master merging without conflict. Makes any SQLite database into a local-first sync target.
Local-first platform built on SQLite β type-safe schemas, end-to-end encryption with user-owned mnemonic key, sync across devices.
Local-first, end-to-end encrypted database that runs in the browser. Verifiable storage with content-addressed CRDT log; pluggable replication.
Distributed, real-time graph database for the web. Peers sync directly in the browser using a conflict-resolution algorithm; relays optionally help with discovery and persistence.
Live-shared linked data as a library β CRDT-based JSON-LD that any number of clients edit concurrently and converge without a central server.
Peer-to-peer database built on IPFS. Provides several CRDT-backed store types (log, feed, key-value, document) that sync between peers without a central server.
Postgres-to-SQLite sync service for offline-first apps. Server tracks per-user data buckets and streams diffs to client SQLite stores.
Client-side sync engine for offline-capable web apps. Local SQLite-style mutation log replays through a server-defined replication function.
Reactive, offline-first NoSQL database for browser and Node. Pluggable storage backends and pluggable replication (CouchDB, GraphQL, WebRTC, P2P).
Decentralized relational tables anchored to EVM chains. Permissions enforced on-chain; queries served by a permissionless validator network.
Open-source local-first sync database. Triplestore data model with relational queries, real-time sync, and offline-by-default semantics.
Reactive database for React/React Native β lazy-loaded SQLite with built-in synchronization protocol for offline-first apps at scale.
Network of interoperable blockchains connected by IBC (Inter-Blockchain Communication). Cosmos SDK lets developers spin up app-specific chains.
Decentralized marketplace for computation. Requestors rent CPU/GPU time from providers worldwide; payment and matching brokered on-chain.
Agent-centric framework for distributed applications. Every participant maintains their own signed source chain and validates a shared DHT, rather than a global consensus blockchain.
Distributed swarm-of-peers networking layer underpinning Hypercore. Uses a Kademlia DHT for discovery and direct UDP/UTP connections.
Homepage: https://iroh.computer
Peer-to-peer networking and content-addressed data toolkit from number0. Provides direct QUIC connections between devices (with relay fallback), blob transfer, and document sync built on Willow-inspired concepts.
Modular peer-to-peer networking stack β transports, multiplexing, peer discovery, DHTs, pub/sub. Used by IPFS, Filecoin, Ethereum, and many others.
C library implementing the SSH protocol β used by KDE, GitLab, and many tools as their SSH backend.
Modular Rust framework for building blockchains. Powers Polkadot, Kusama, and dozens of independent chains via shared runtime primitives.
Fork of Pleroma maintained by a different community. ActivityPub-compatible microblogging server with additional features and a distinct moderation stance.
Aaron Parecki's Microsub server β fetches your subscribed feeds and exposes a Microsub API for clients like Monocle to render.
Modular federated social platform built in Elixir. Aims to let communities assemble custom social experiences (microblogging, groups, classifieds, etc.) on shared ActivityPub plumbing.
Federated social reading platform β a Goodreads-style site built on ActivityPub. Lets users track reading, review books, and follow readers across instances.
Hosted webmention bridge from silos (Twitter, Facebook, etc.) to personal websites. Predecessor to Bridgy Fed.
Bridges between ActivityPub, AT Protocol/Bluesky, and Nostr. Lets users on one network follow and reply to users on the others.
Federated social network built on XMPP, with channels analogous to topic-based feeds. Defunct.
Federated comment system for the web backed by Matrix. Each comment thread is a Matrix room; readers comment with any Matrix account.
Self-hosted podcast platform with built-in ActivityPub federation. Listeners on any Fediverse server can follow shows and discuss episodes inline.
High-performance NNTP server written by Matt Dillon (DragonFlyBSD) for handling the firehose of full-feed Usenet traffic at ISP scale.
Early federated social network organized around user-run "pods" and aspect-based sharing. Uses its own Diaspora federation protocol rather than ActivityPub.
Peer-to-peer video sharing platform built on the Hive blockchain with IPFS for content storage. YouTube-style UI, blockchain-anchored social layer.
Federated social server that speaks multiple protocols (ActivityPub, Diaspora, OStatus, ATOM/RSS). Designed for cross-network interoperability.
Federated audio platform for music, podcasts, and other sounds. Communicates over ActivityPub so libraries on different instances can be browsed and followed.
Lightweight federated events platform β create and share events with ActivityPub-aware calendars without a user account.
Modern publishing platform with built-in newsletters, memberships, and (since 2024) ActivityPub federation for cross-fediverse following.
Mastodon fork with experimental features that may or may not land upstream β local-only posts, content types, formatting toolbar, granular reply controls.
Federated microblogging server descended from StatusNet (the software that ran identi.ca). Interoperates with the Fediverse via OStatus and ActivityPub.
Lightweight Go-based ActivityPub server. Mastodon-API compatible but designed to run comfortably on small/low-power instances.
Blockchain-based social media platform forked from Steem in 2020. Posts, votes, and tokens live on-chain; clients (PeakD, Ecency) read the same data.
Mastodon fork emphasizing local community: local-only posting, larger character limits, full content from federated instances.
Minimalist single-user ActivityPub server. No likes, no notifications, no algorithms β just federated honking.
Federated platform built around "nomadic identity" β accounts can clone across hubs so identity survives any one server going down. Supports ActivityPub and the Zot protocol.
Misskey-lineage ActivityPub server with a rewrite-in-progress (Iceshrimp.NET) aimed at a cleaner codebase and better federation behavior.
Self-hosted IndieWeb server providing Micropub, Webmentions, and content syndication endpoints for a personal site.
InterNetNews β the dominant NNTP server for the open Usenet hierarchy. Stewarded by ISC; still maintained by Russ Allbery.
Federated book inventory and lending network. Catalog data sourced from Wikidata; ownership and lending tracked per user across federated instances.
Federated link aggregator and microblog combining Lemmy-style threaded discussion with Mastodon-style posting. The original project is dormant; the community now develops Mbin.
IndieWeb-flavored publishing platform supporting POSSE (publish on own site, syndicate elsewhere), micropub, and webmentions.
Small NNTP server for individuals β pulls a subscribed subset of groups from an upstream and serves them locally. The "personal news server" tier.
Federated link-aggregator and discussion forum, similar in shape to Reddit. Communities live on individual instances and federate over ActivityPub.
Federated microblogging server speaking ActivityPub. Independently operated instances form a shared social network with local and federated timelines.
Community-maintained fork of Kbin. Threaded discussion and microblogging in one federated ActivityPub server.
Federated media publishing platform β images, video, audio. Predates ActivityPub; uses the older Pump.io / ActivityStreams flow.
Hosted (with self-host option) blogging-first social platform built on RSS, IndieWeb, and ActivityPub. Posts originate as plain feeds and federate outward.
Single-user ActivityPub microblogging server. Designed to be self-hosted by one person, with the fediverse as the social layer.
Feature-rich ActivityPub server with reactions, custom emoji, drive storage, and rich timelines. Popular in the Japanese Fediverse and basis for several forks.
Rust ActivityPub server with built-in monetization features (subscriptions, tips) on top of standard Fediverse interop.
Federated platform for organizing events and groups. Speaks ActivityPub so events and RSVPs can be discovered and joined from across the Fediverse.
Social and chat front-end on top of XMPP. Gives the federated XMPP network a modern social-network UI with posts, comments, and groups.
Federated catalog of books, films, music, podcasts, and games with personal shelves and reviews. Speaks ActivityPub so entries and reviews flow into the Fediverse.
Modern forum software with optional ActivityPub federation. Topics and posts can be shared between NodeBB instances and the wider fediverse.
Collaboratively edited open map of the world. Single centralized database but openly licensed, with many independent renderers, mirrors, and forks downstream.
Self-hosted live video and chat server. Streams to a single instance but supports ActivityPub for federated discovery and follower notifications.
Federated video hosting platform on ActivityPub. Uses WebTorrent for peer-assisted video delivery, reducing bandwidth load on instances.
Lemmy-alternative federated link aggregator written in Python. Speaks ActivityPub to the rest of the Threadiverse.
Federated photo-sharing platform on ActivityPub, with an Instagram-like UX. Self-hostable and interoperable with the wider Fediverse.
Lightweight federated microblogging server written in Elixir. Implements ActivityPub and is Mastodon-API compatible.
Federated long-form blogging platform speaking ActivityPub. Multi-author "blogs" can be followed and commented on from anywhere in the Fediverse.
Federated activity streams server, the successor to identi.ca. Its protocol directly influenced ActivityPub.
Self-hosted, single-user bookmark manager. Generates Atom/RSS feeds, supports tagging, runs as static-ish PHP with no database.
Misskey fork focused on improvements to moderation, accessibility, and UX. Federates with the rest of the ActivityPub-speaking Fediverse.
Federated social network in the shape of early VK / Facebook β walls, photos, groups β speaking ActivityPub to the rest of the Fediverse.
Minimalist single-user ActivityPub server in C. Designed to be tiny, self-contained, and easy to self-host on small hardware.
Federated personal profile and stream server. Speaks both the Diaspora protocol and ActivityPub.
Homepage: https://solidproject.org
Tim Berners-Lee's specification for decentralized web applications. Users store data in personal "pods" they control, and apps request access via WebID-based authentication and Linked Data permissions.
Federated microblogging platform that powered identi.ca. Renamed and continued as GNU social; conceptual predecessor of Mastodon.
First blockchain social network β posts, votes, and tokens on-chain. Hostile takeover in 2020 triggered the Hive fork; the original chain continues as Steem.
Mike Macgirvin's successor to Hubzilla β a federated social platform with nomadic identity, speaking ActivityPub (and Nomad/Zot extensions).
Multi-domain ActivityPub server written in Django. One install can host accounts under many domains from a shared infrastructure.
Decentralized microblog built on signed Atom feeds with strong identity. Aimed at a Twitter alternative without a central server. Defunct.
Distributed discussion system from 1980 using NNTP to propagate articles between servers. The original federated social network β newsgroups still operate today.
Official WordPress plugin that exposes blogs and authors as ActivityPub actors. Lets Fediverse users follow and comment on WordPress posts.
Minimalist federated blogging platform. Published posts can be followed from Mastodon and other Fediverse software over ActivityPub.
Go-based OpenPGP keyserver. The current backbone of keys.openpgp.org and the most maintained federated PGP keyserver implementation.
Decentralized OpenPGP-based identity verification β proves you control a set of accounts via signed claims pointed to from notations in your OpenPGP key. Federated, no central registry.
Federated avatar hosting service β DNS SRV lookup directs requests to the avatar server for a given email domain. Decentralized alternative to Gravatar.
Synchronizing Key Server β federated PGP keyserver pool. Famous for the 2019 "poisoned key" attack that effectively killed the SKS network and pushed users to Hagrid and Hockeypuck.
Open-source PBX from Mark Spencer (also IAX2's author). Practically every open-source telephony stack of the last 25 years is built on Asterisk.
IRC services package (NickServ/ChanServ/OperServ-style network services). Pairs with Solanum/Charybdis on most modern IRC networks.
ircd-ratbox fork that became the dominant IRCd of freenode (and is now succeeded by Solanum after the Libera.Chat split).
Lightweight single-binary Matrix homeserver in Rust, optimized for personal and small-group self-hosting.
Active fork of Conduit after upstream development slowed. Rust homeserver, single-binary, less resource-heavy than Synapse.
Integrated mail server stack covering SMTP, IMAP, POP3, and webmail. Less common than Postfix+Dovecot today but historically popular in shared-hosting environments.
IMAP/POP3 server from Carnegie Mellon's Project Cyrus, designed for large multi-thousand-account deployments with a custom mail store rather than Maildir/mbox.
Second-generation Matrix homeserver in Go, focused on horizontal scaling and microservice-style deployment.
IMAP and POP3 server by Timo Sirainen, prized for speed and standards compliance. The de-facto mail-delivery-agent paired with Postfix or Exim on modern Linux mail stacks.
Highly scalable Erlang XMPP server. Powers many large federated chat deployments and also speaks MQTT and SIP.
MTA from the University of Cambridge with a famously flexible configuration language. Default MTA on Debian for many years; powers a large share of cPanel-managed hosting.
Soft switch / VoIP platform from former Asterisk devs. Used heavily as the backend for conferencing services (Jitsi Videobridge predates it; SignalWire commercializes it now).
Another Conduit-fork; smaller community focus, emphasizes long-term maintainability and a different patch policy than conduwuit.
Node.js SMTP server designed for high-throughput modern deployments. Plugin-architected; used as a programmable mail-routing platform rather than a traditional MTA.
Module-architected IRCd written from scratch in C++; emphasizes runtime-loadable feature modules.
Long-running EFnet-family IRCd; ancestor of Charybdis, Solanum, and ircd-ratbox.
The original Jabber/XMPP server by Jeremie Miller, the protocol's creator. Frozen at version 1.4.x but historically the first XMPP server.
Rewrite of the original jabberd in C. Component-based architecture; still maintained but largely overshadowed by Prosody and Ejabberd.
SIP server / proxy / load balancer; one of two surviving SER (SIP Express Router) descendants alongside OpenSIPS.
Turnkey email server installer for a single Ubuntu VPS β IMAP, SMTP, webmail, DNS, spam filtering, and TLS in one box.
Erlang XMPP server from Erlang Solutions, descended from Ejabberd. Targets mobile/IoT messaging deployments at scale.
Low-latency voice chat. Server (Murmur) is self-hostable; each server is independent (no federation between Mumble servers). Long the standard for gaming/comms communities preferring self-hosting over Discord/TeamSpeak.
"Next-generation" IRCd from-scratch rewrite emphasizing IPv6, RFC compliance, and small size.
Java XMPP server, originally Wildfire from Jive Software. Long-time enterprise XMPP option; ships a web admin UI and rich plugin ecosystem.
The other SER fork; SIP server widely deployed by VoIP carriers and enterprise telecom.
OpenBSD's SMTP server β privsep-friendly, small codebase, terse configuration. Distributed with OpenBSD as the default MTA.
High-performance open-source MTA developed by Wietse Venema at IBM Research, designed as a more secure replacement for Sendmail. Default MTA in many Linux distributions and the most-deployed open SMTP server on the internet.
Lightweight, modular XMPP server written in Lua. A common choice for self-hosted federated chat.
Security-minded MTA written by D. J. Bernstein. Famously DJB-licensed (public domain only since 2007) and famously hostile to standards drift; spawned a generation of forks (netqmail, indimail).
Self-hosted PHP webmail with a desktop-like AJAX interface. The most widely deployed open-source webmail.
Whistleblower submission system run by news organizations. Sources connect via a Tor onion service to deliver documents to journalists without revealing their identity.
The original Unix MTA, written by Eric Allman at Berkeley. Infamously complex configuration and a long history of security CVEs; nevertheless ran a vast majority of internet mail for two decades.
Fork of RainLoop after the latter went unmaintained β actively developed open-source webmail with a single-page UI.
Packaged XMPP for self-hosting. Bundles a server, mobile clients, and configuration tooling for small groups who want chat infrastructure without operating each piece themselves.
Modern IRC bouncer designed for mobile/multi-device usage with IRCv3 protocol extensions. From Simon "emersion" Ser, who also writes aerc and several Wayland tools.
Charybdis fork maintained by Libera.Chat staff; powers libera.chat and several other major IRC networks.
Java XMPP server emphasizing scalability and modular components. Powers BeagleIM and Siskin (Tigase's clients).
Long-lived IRCd from the DALnet/Bahamut lineage, popular on community IRC networks and for self-hosted IRC.
PHP CalDAV/CardDAV server built on SabreDAV. The most-deployed self-hosted CalDAV+CardDAV stack for shared hosting environments.
End-to-end encrypted collaborative office suite (documents, sheets, slides, kanban). Servers store only encrypted blobs; keys are derived from URLs.
File-based PHP wiki β no database, just text files. Default choice for small team and project documentation wikis.
Real-time collaborative document editor. Self-hosted, with thousands of public instances; influenced the design of Google Docs.
TWiki fork after TWiki went semi-proprietary. Perl wiki popular in enterprise documentation and project management.
Collaborative markdown editor with live preview, originally forked from HackMD/CodiMD. Self-hostable; popular for shared notes and meeting minutes.
Open source video-conferencing platform built on WebRTC and the Jitsi Videobridge SFU. Easy to self-host; many independent public instances; optional E2EE.
Open source real-time audio/video infrastructure based on WebRTC. Self-hostable SFU plus SDKs for embedding calls and live audio into apps.
The wiki engine powering Wikipedia. Sprawling PHP codebase, but the dominant self-hosted wiki for any project at scale.
Python wiki engine; powered python.org, kernelnewbies.org, and many Python-community sites in the 2000s and 2010s.
PHP wiki by Patrick Michaud emphasizing easy customization, file-based storage, and "WikiWord" linking. Niche but long-running.
Lightweight Python CalDAV/CardDAV server. Easy to self-host; default choice for personal calendar/contacts sync.
Federated wiki where every reader can fork pages into their own site. Edits propagate as forks across personal wikis rather than mutating shared text.
Single-HTML-file wiki: the entire wiki lives in one file you can email around. Pioneer of the "local-first personal knowledge base" pattern.
Hierarchical note-taking app with rich text, code, mind maps. Server-sync between desktop and self-hosted instance.
Ward Cunningham's original wiki β the first wiki β at c2.com/cgi/wiki. Birthplace of the term "wiki" and of the patterns-language movement.
Distributed database with blockchain characteristics β Tendermint consensus, MongoDB storage, immutable signed transactions. Largely inactive since 2020.
Personal cloud platform β files, contacts, photos, banking aggregation. Designed for self-hosting or as a managed service from Cozy Cloud.
Open-source research-data repository platform from Harvard's Institute for Quantitative Social Science (2006). Citable datasets with versioning, persistent identifiers, fine-grained access controls, and per-dataverse customization within a single installation. Federation via Dataverse-network harvesting plus OAI-PMH.
Open-source institutional repository platform, originally from MIT Libraries and HP Labs (2002). Runs at ~3000+ universities and libraries worldwide hosting papers, theses, datasets, and digitized collections. Federation via OAI-PMH harvesting; maintained today by LYRASIS.
Open-source institutional repository software from the University of Southampton (2000). DSpace's older contemporary, written in Perl; widely deployed across UK and European universities. Federation via OAI-PMH; one of the early engines of the open-access movement, with Stevan Harnad as its most public advocate.
Flexible digital-object repository platform from Cornell + UVA (first public release 2003; concepts from a 1997 Cornell research project). Not a turnkey repository β Islandora, Samvera/Hyrax and other stacks build user-facing systems on top of Fedora's storage and metadata core. Unrelated to Red Hat's Fedora Linux distribution.
"Lots of Copies Keep Stuff Safe." Library-federation for digital preservation: each member library runs a LOCKSS box that crawls subscribed content and continuously peer-audits other boxes via a voting protocol to detect tampering or bit-rot. Actually deployed at scale across academic libraries worldwide.
Self-hosted file storage, collaboration, and groupware platform. Nextcloud servers can federate shares with each other via the Open Cloud Mesh protocol.
Self-hosted file sync and share platform, the parent project from which Nextcloud forked. Supports federated sharing via the Open Cloud Mesh protocol.
End-to-end encrypted personal storage on IPFS. Cryptree-based access control lets you share by capability without trusting the server.
Modular FTP server with Apache-style configuration. Long-running, with extensive plugin ecosystem for LDAP backends, SQL accounting, and TLS.
Compact security-focused FTP server by Frank Denis (also of libsodium fame). Designed to be safer than wu-ftpd and simpler than ProFTPD.
Self-hosted file sync and sharing platform. Originally AjaXplorer (2008); modern Pydio Cells server (Go) with sync and collaboration features.
Self-hosted file sync and share β Dropbox alternative with optional client-side encryption per library. Server in C and Python, mature clients across platforms.
The first Internet search engine. Periodically crawled anonymous FTP sites and built a queryable filename index. Predecessor to Veronica, Jughead, and ultimately the web search engines.
Independent open-source search engine indexing the small/non-commercial web. Operated as marginalia.nu by Viktor Lofgren; AGPL-licensed and self-hostable.
Open-source community-curated search engine. Volunteers contribute index entries; the codebase is small enough to comprehend and self-host.
Open source metasearch engine that aggregates results from many upstream engines without tracking. Forked as SearXNG.
Self-hostable metasearch engine that aggregates results from many upstream search engines without tracking. A loose federation of independently operated public instances.
Small SSH server/client for embedded systems and minimal environments. Common in OpenWrt, BusyBox-based images, and constrained-environment Docker.
Open-source, self-hosted implementation of the Tailscale control server. Lets a group of devices form a private WireGuard mesh without relying on Tailscale's hosted coordinator.
Peer-to-peer content distribution library for mobile apps β fetches resources from nearby peers when servers are blocked or unreachable.
OpenBSD's free SSH implementation β the dominant SSH server and client on Unix-likes. Ships in basically every Linux distribution.
Federation protocol for git forges β extends ActivityPub with vocabulary for repositories, issues, pull requests, and CI events.
ActivityPub-based federation for the Forgejo (and Gitea-lineage) self-hosted code forge. Aims to let issues, stars, and follows cross instance boundaries.
Open source self-hosted Git forge. Friendly fork from Gogs; Forgejo later forked from Gitea.
Simple Rust Gemini server β serves a directory tree, handles TLS, and not much else. The Gemini equivalent of thttpd.
The original Apache. Ran the majority of websites for the first two decades of the web; module ecosystem (mod_*) gave us mod_php, mod_dav, mod_perl, and more.
Perl Gopher server from Floodgap. The classic post-2000 small-Gopher server, still serves Floodgap's archive.
Modern Go-based web server. Automatic HTTPS via Let's Encrypt by default; the easiest way to put a TLS-terminated server up.
Long-running PHP CMS. Heavier than WordPress but considerably more flexible β popular for government and enterprise sites.
Rust Gemini server emphasizing speed and TLS-config flexibility. Supports CGI and SCGI.
Tiny Gopher daemon used heavily in the Tildeverse community. Suckless-style minimalism.
OpenBSD-flavored Gemini server with httpd-style configuration syntax. Sandboxed via pledge/unveil on OpenBSD.
Modern Gopher server in C. Default Gopher server on many active capsules in the 2010s revival.
HTTP-to-Gemini proxy by Drew DeVault. Run it in front of a Gemini capsule and the HTTP-only web sees a styled HTML version transparently.
Lightweight web server emphasizing low memory footprint. Once popular for static sites and Rails/Django backends before Nginx took over that niche.
Reference Gemini server from Solderpunk, the protocol's designer. Go-based, configurable, supports user pages and CGI.
Easy-to-configure Gopher server in C. Supports CGI and gophermaps; intentionally targets simple self-hosting.
Event-driven web server from Igor Sysoev, designed for the C10K problem. Now the most-deployed web server on the internet; widely used as reverse proxy and load balancer.
Minimal HTTP server shipped with OpenBSD; designed for static files and FastCGI, similar in role to thttpd or boa.
Python Gopher server with plugin support and HTTP/Gopher dual-protocol modes. Long-running, packaged for Debian.
Configurable Gemini server with virtual-host support, CGI, redirects, and user pages.
Lightweight PHP blog/CMS with a XML-like template tag language. The civilized alternative to WordPress for the 2000s blogosphere.
Tiny, single-threaded web server. Once popular for low-resource hosting and embedded-device admin UIs.
HTTP-accelerator / reverse proxy / cache from Poul-Henning Kamp (FreeBSD). Widely deployed in front of large content sites.
Aaron Parecki's Microsub server β fetches your subscribed feeds and exposes a Microsub API for clients like Monocle to render.
PHP CalDAV/CardDAV server built on SabreDAV. The most-deployed self-hosted CalDAV+CardDAV stack for shared hosting environments.
Open-source research-data repository platform from Harvard's Institute for Quantitative Social Science (2006). Citable datasets with versioning, persistent identifiers, fine-grained access controls, and per-dataverse customization within a single installation. Federation via Dataverse-network harvesting plus OAI-PMH.
File-based PHP wiki β no database, just text files. Default choice for small team and project documentation wikis.
Long-running PHP CMS. Heavier than WordPress but considerably more flexible β popular for government and enterprise sites.
Open-source institutional repository platform, originally from MIT Libraries and HP Labs (2002). Runs at ~3000+ universities and libraries worldwide hosting papers, theses, datasets, and digitized collections. Federation via OAI-PMH harvesting; maintained today by LYRASIS.
Open-source institutional repository software from the University of Southampton (2000). DSpace's older contemporary, written in Perl; widely deployed across UK and European universities. Federation via OAI-PMH; one of the early engines of the open-access movement, with Stevan Harnad as its most public advocate.
TWiki fork after TWiki went semi-proprietary. Perl wiki popular in enterprise documentation and project management.
Self-hosting platform sponsored by the FreedomBox Foundation. Pure-Debian system with web-based admin for running personal communication and storage services.
The wiki engine powering Wikipedia. Sprawling PHP codebase, but the dominant self-hosted wiki for any project at scale.
Python wiki engine; powered python.org, kernelnewbies.org, and many Python-community sites in the 2000s and 2010s.
PHP wiki by Patrick Michaud emphasizing easy customization, file-based storage, and "WikiWord" linking. Niche but long-running.
Lightweight Python CalDAV/CardDAV server. Easy to self-host; default choice for personal calendar/contacts sync.
Self-hostable platform for running web apps in capability-secured sandboxes. Each "grain" is an isolated instance shared via cryptographic capability URLs.
Self-hosting OS focused on sovereignty and Tor-by-default networking. Ships an app store of self-hosted services and runs on Raspberry Pi / dedicated hardware.
Lightweight PHP blog/CMS with a XML-like template tag language. The civilized alternative to WordPress for the 2000s blogosphere.
Single-HTML-file wiki: the entire wiki lives in one file you can email around. Pioneer of the "local-first personal knowledge base" pattern.
Linux distribution for personal servers β install IndieWeb apps (Nextcloud, Mastodon, WordPress, etc.) by name with one command. Successor to Indie Box Project.
Home server OS for running self-hosted apps (Nextcloud, Bitcoin node, Jellyfin, etc.) on a Raspberry Pi or x86 box. Provides an app store and a single-user dashboard.
Personal server stack designed from scratch β a deterministic OS (Arvo), functional language (Hoon), and overlay identity/network (Azimuth, Ames). Each user runs their own "ship."
Ward Cunningham's original wiki β the first wiki β at c2.com/cgi/wiki. Birthplace of the term "wiki" and of the patterns-language movement.
Java wiki / application platform β used as the backend for structured-data wikis and Notion-style internal docs.
Distributed peer-to-peer public-discussion network. Posts are replicated across all participating nodes; communities are ephemeral and locally moderated.
An Aether universe is the single place where your online community gathers. Each universe can have as many subs as needed, which can be created and joined by members of the community. Each sub has its own chat room, forum threads, and email newsletters.
https://aether.app/features/general/
Decentralized social network built on Ethereum and IPFS. Posts, identities, and reputation anchored in the dweb stack.
Microblogging social network built on the AT Protocol. The reference implementation of atproto and its largest deployment.
Mobile (and desktop) client for Secure Scuttlebutt. Brings off-grid, peer-to-peer social feeds to phones with no servers or accounts.
Microsub client that pairs with Aperture (or any Microsub server) to give a reader UI for indieweb feeds.
Defunct decentralized peer-to-peer marketplace using IPFS for storage and Bitcoin for payments. The company shut down in 2021 but the protocol design and code remain a useful reference for trust-minimized commerce.
GTK newsreader with batch downloading, binary-attachment yEnc decoding, and threaded views. The graphical newsreader most current Usenet readers use.
Desktop client for Secure Scuttlebutt β reads and writes the local SSB log and syncs with peers over the gossip protocol.
Beaker-based peer-to-peer microblog where each user hosts their own Dat site. Followed peers' Dats directly; no servers. Defunct with Beaker.
Terminal newsreader with S-Lang scripting. Long-running, popular among text-mode users.
Threaded terminal newsreader. Direct lineage from rn/trn, in continuous development since the early 90s.
Threaded rn β first newsreader to score articles by Subject thread, descended from Larry Wall's original rn. Foundational to the threaded-discussion UX.
Defunct peer-to-peer microblogging platform combining BitTorrent for content distribution and a Bitcoin-style blockchain for user registration.
The free implementation of OpenPGP. By Werner Koch since 1997; the canonical signing and encryption tool for software distribution and email crypto on Linux.
Distributed reputation and identity protocol β web-of-trust ratings signed by keypairs, no central registrar. Inspiration for several later WoT systems.
Self-sovereign identity wallet and SDK. Hierarchical-deterministic DIDs anchored to Ethereum or IPFS for credential exchange.
Terminal mail client from Drew DeVault with first-class support for IMAP, JMAP, and Maildir, plus a tab-based UI and patchset workflow for mailing-list contributors.
Terminal mail client from the University of Washington, originally called Pine. Re-released as Alpine in 2006 under an open license.
Peer-to-peer end-to-end encrypted messenger built on libp2p and IPFS. Works without internet over Bluetooth or local network.
Bluetooth-mesh peer-to-peer chat app. No internet, no servers, no accounts β phones in proximity form an encrypted gossip network.
Peer-to-peer encrypted messenger that syncs over Tor, Bluetooth, or local Wi-Fi. Has no central servers β designed for activists and journalists in hostile network conditions.
Peer-to-peer group chat built on Hypercore append-only logs. Channels are addressed by a shared key; there are no servers, accounts, or central moderators.
Sylpheed fork turned independent; GTK-based desktop client emphasizing keyboard-driven workflow and a powerful plugin system.
Open source Android XMPP client with first-class OMEMO end-to-end encryption. Popular reference client for modern XMPP.
Metadata-resistant, decentralized group chat that runs as a Tor onion service per user. Successor in spirit to Ricochet, with multi-party conversations and offline message delivery.
Self-hosted federated messaging server with end-to-end encryption. Mobile and web clients connect to any Databag node and chat across nodes.
Chat client that uses ordinary email (IMAP/SMTP) as transport, with Autocrypt-based end-to-end encryption. Federation is inherited from the global email system.
Modern, end-to-end encrypted XMPP client for desktop. GTK-based, supports OMEMO, audio/video calls via Jingle.
Flagship Matrix client (originally Vector / Riot). Provides desktop, web, and mobile interfaces to any Matrix homeserver.
GNOME's integrated mail/calendar/contacts client. The Exchange-talking PIM suite of the Linux desktop world.
Long-running cross-platform XMPP client written in Python/GTK. Full feature set including OMEMO, MUC, file transfer.
Modern, conversation-view-first GNOME mail client. Originally from the Yorba Foundation, adopted by GNOME after Yorba dissolved.
Modern Rust IRC client built on the Iced GUI toolkit. Newer entrant emphasizing IRCv3 support and a clean look.
Cross-platform GTK IRC client; XChat fork after XChat went semi-proprietary on Windows. The default graphical IRC client on Linux desktops.
Rust CLI mail client supporting IMAP, Maildir, JMAP, and Notmuch backends. Designed for scripting and integration with editor workflows.
Terminal IRC client by Timo Sirainen (also author of Dovecot). Aggressively scriptable in Perl; classic Unix-power-user IRC interface.
GNU peer-to-peer communication platform for messaging, voice, and video. Uses an OpenDHT-based distributed network to discover peers; no accounts on any central server.
Peer-to-peer audio/video/chat app built by Holepunch on the Pear runtime. No servers β calls and rooms are negotiated directly between participants.
Browser-based IRC client deployable as both a hosted service (kiwiirc.com) and a self-hostable web app. Popular for embedded chat on project sites.
KDE's mail client, the mail component of the Kontact PIM suite. One of the oldest still-developed Linux desktop mail clients.
KDE's IRC client. Long-running, easy to set up for new IRC users compared to terminal options.
Self-hosted webmail client with built-in PGP and a search-first UI. Runs locally; speaks IMAP/SMTP to any provider.
Terminal mail client written in Rust. NeoMutt-style key bindings; supports IMAP, JMAP, Maildir, mbox, notmuch.
Emacs front-end to the mu mail indexer. Similar role to notmuch-emacs; popular among Emacs-centric mail workflows.
Classic terminal mail client. The aphorism "All mail clients suck. This one just sucks less" is from its docs.
Mutt fork that incorporates a large body of long-standing patches and adds notmuch integration, sidebar, and other modern affordances.
Mail indexer rather than full client β provides Xapian-backed tag-and-search over local Maildir; multiple front-ends (notmuch-emacs, alot, astroid) wrap it.
Tool for securely and anonymously sharing files, hosting websites, and chatting via Tor onion services. Each share spins up an ephemeral onion service on the sender's machine.
Multi-protocol instant messaging client. Started as Gaim (1998); supports XMPP, IRC, and (historically) AIM, MSN, Yahoo, ICQ via libpurple.
Infrastructure-independent peer-to-peer mesh messenger over Bluetooth, Wi-Fi, and LAN. Works without internet, mobile data, or central servers.
Distributed Qt-based IRC client split into a core (always-connected) and clients (desktop, mobile, web). Pre-dated and prefigured Matrix's account/device model.
Friend-to-friend encrypted communication platform β messaging, forums, file sharing, and mail across a network of explicitly trusted contacts.
Original anonymous peer-to-peer instant messenger using Tor onion services. Discontinued; lineage continued as Ricochet Refresh and Cwtch.
Anonymous peer-to-peer instant messenger. Each user is reachable as a Tor onion service, so there are no servers, accounts, or metadata trails. Continuation of the original Ricochet project.
Long-developed (and still mostly aspirational) project for a fully decentralized social network on top of GNUnet. A reference design for federation-without-servers thinking.
End-to-end encrypted messenger that routes traffic through a decentralized network of service nodes (onion routing). Uses anonymous public-key identifiers instead of phone numbers or emails.
End-to-end encrypted messenger using the Signal Protocol (Double Ratchet). Open source clients and server but operated as a single centralized service by the Signal Foundation.
Messaging protocol with no user identifiers at all. Conversations route through unidirectional queues on (potentially many) relay servers, so even the network can't link two parties via a shared ID.
Open source mobile messenger built on the Waku peer-to-peer protocol, with an Ethereum-based identity and wallet.
Self-hosted web IRC client with always-on connection, push notifications, and persistent history. Effectively a bouncer + web client in one.
Mozilla's open-source mail client. After near-abandonment in the mid-2010s, MZLA has actively redeveloped it into a modern multi-protocol mail/calendar/chat client.
Peer-to-peer encrypted instant messaging and audio/video calling protocol. Friend discovery happens via a public DHT; conversations are end-to-end encrypted with no servers in the middle.
Encrypted friend-to-friend chat and file sharing system briefly released by Nullsoft/AOL in 2003 and quickly pulled. Code survives as community forks; influenced RetroShare.
Extensible terminal chat client supporting IRC, Matrix (via plugins), XMPP, and more. Successor to Irssi for many users; rich Lua/Python plugin ecosystem.
Local-first, end-to-end encrypted knowledge graph. Object-typed blocks sync peer-to-peer with optional backup nodes; no central server holds plaintext.
Federated research-data management built on git-annex. Treats datasets as nested git repos with content addressable across any backend (S3, institutional storage, HTTP, IPFS, β¦); used heavily in neuroscience for sharing TB-scale datasets across labs without centralizing them.
Real-time collaborative drawing β multiple users on the same canvas. Public sessions on drawpile.net or self-hosted; clients also act as servers (p2p over TCP).
Peer-to-peer audio/video/chat app built by Holepunch on the Pear runtime. No servers β calls and rooms are negotiated directly between participants.
Local-first outliner-based knowledge graph. Files stored as Markdown/Org on disk; optional encrypted sync between devices.
Doug Engelbart's NLS β the system demoed at "The Mother of All Demos" (1968): hypertext, multi-user collaboration, shared screen, mouse. Commercialized as Augment by Tymshare; conceptually decades ahead of its time.
Local-first, self-hosted personal knowledge management. Block-based notes with bidirectional links, stored as plain JSON on disk.
Cross-platform eDonkey/Kad client β fork of eMule for Linux/macOS. Still alive on the Kad network.
Anonymous p2p network in Java, similar mixnet-flavored routing to MUTE. Discontinued.
Deduplicating, compressing, encrypted backup program. Stores chunk-indexed backups to local or SSH-reachable repositories.
Securely transfer files between two computers from any network using a relay and PAKE-derived key. Cross-platform Go binary.
macOS/Windows file-transfer client with native UI, supporting FTP/SFTP, WebDAV, S3, Google Drive, and friends. The de-facto Mac FTP client.
Federated research-data management built on git-annex. Treats datasets as nested git repos with content addressable across any backend (S3, institutional storage, HTTP, IPFS, β¦); used heavily in neuroscience for sharing TB-scale datasets across labs without centralizing them.
Open-source eDonkey2000 client. Added the Kademlia-based Kad network as a serverless overlay when the original eDonkey indexers were shut down.
End-to-end encrypted, secure sync for contacts, calendars, tasks, and notes. Server only sees opaque ciphertext.
Browser-to-browser file transfer via WebTorrent. Recipient downloads directly from the sender's browser; no server stores the file.
Cross-platform graphical FTP/SFTP/FTPS client by Tim Kosse. The most-installed open-source FTP client; ships a separate server (FileZilla Server) for Windows.
LimeWire fork β kept going after LimeWire's shutdown, eventually pivoting to BitTorrent. Still maintained.
Streaming file transfer over WebTorrent β drag a file in the browser, share the magnet, recipient downloads via the same WebTorrent swarm.
Java Gnutella client. Briefly the most-downloaded p2p file-sharing app worldwide before legal shutdown in 2010. Reborn as LimeWire DAO recently (different focus).
Get things from one computer to another, safely. Short human-readable codes authenticate a direct PAKE-secured transfer between two peers.
Anonymous p2p file-sharing inspired by ant-colony routing. Each query is forwarded by random hops; you can't tell who originated a search. Discontinued.
Local-first, end-to-end encrypted decentralized graph database and collaboration platform built on RDF and CRDTs.
Homepage: https://perkeep.org
Open-source personal storage system for life's data. Content-addressed, schema-flexible storage designed to outlive any single service, with support for syncing across multiple backends.
Command-line program to sync files and directories to and from dozens of cloud storage providers β "rsync for cloud storage."
Peer-to-peer file sync using the BitTorrent protocol. Originally BitTorrent Sync (2013), spun out to Resilio in 2016. Proprietary.
Fast incremental file transfer utility using a rolling-checksum algorithm to send only changed parts of files. Foundation of nearly every later sync tool.
WebRTC-based file sharing in the browser β Apple AirDrop-style transfer between devices on the same network or via a room code.
Self-hosted file sync using Git as the storage backend. Drop files in a folder; SparkleShare commits and pushes to your Git server.
Continuous peer-to-peer file synchronization between devices. Uses a global discovery server for NAT traversal but transfers are direct, end-to-end encrypted, and require no third-party storage.
Homepage: https://tahoe-lafs.org
Distributed, encrypted, fault-tolerant filesystem. Uses erasure coding to spread encrypted shares across untrusted storage nodes, with capability-based access control via cryptographic URIs.
Anonymous BitTorrent client that routes traffic through other Tribler users (Tor-like) for download privacy. Also experiments with decentralized search and content discovery.
Berkeley Open Infrastructure for Network Computing β volunteer compute framework. Each project (SETI@home, Rosetta@home, etc.) runs its own BOINC server; clients donate CPU cycles.
Open-source mesh networking toolkit from the Open Technology Institute, intended for community wireless and resilience in censored or disaster-struck regions.
Volunteer protein-folding simulation. Briefly became the fastest computing system in the world (>1 exaFLOPS) during COVID-19's spike of donated GPU time.
German non-profit community wireless mesh network movement. Local groups run open Wi-Fi nodes that route through batman-adv or babel to share internet uplinks.
GNU framework for secure, decentralized peer-to-peer networking. Provides transport, DHT, pseudonymous identity, and naming primitives intended as a privacy-respecting alternative to internet infrastructure.
Open, free, neutral community mesh network in Catalonia and beyond. Tens of thousands of nodes operated under a shared commons agreement.
Volunteer-run network built on cjdns β the largest deployment of cjdns's encrypted IPv6 mesh, used for community routing experiments.
Firmware framework for community mesh networks. Multi-radio mesh on top of OpenWrt with auto-configuration so devices form a network without per-node setup.
Decentralized VPN marketplace β node operators sell residential exit bandwidth, clients pay per-byte in the network's token over a p2p tunnel.
Fully distributed self-organizing routing protocol intended to scale to billions of nodes via fractal Hamiltonian-cycle topology. Mostly historical.
Free SSH/Telnet/serial client for Windows. For a generation of Windows users, PuTTY was "the terminal."
Open-source remote desktop with optional self-hosted rendezvous and relay servers. Direct p2p connections when network allows.
Mobile-phone mesh network for emergencies and infrastructure-free communication. Phone-to-phone voice and messaging over Wi-Fi without cell towers.
Distributed analysis of radio telescope data for signs of extraterrestrial intelligence. The project that popularized volunteer compute. Paused 2020.
Distributed version control system based on a theory of patches rather than snapshots. Influenced Pijul.
Federated research-data management built on git-annex. Treats datasets as nested git repos with content addressable across any backend (S3, institutional storage, HTTP, IPFS, β¦); used heavily in neuroscience for sharing TB-scale datasets across labs without centralizing them.
Distributed version control with a built-in bug tracker, wiki, and forum. A single self-contained binary aimed at self-hosted code collaboration.
Distributed file management on top of git. Tracks where copies of large files live across many remotes (S3, rsync, removable drives, IPFS) without putting the content into git itself.
Distributed version control based on a sound theory of patches. Resolves merges in cases git handles awkwardly.
Minimal peer-to-peer web browser. First-class fetch support for ipfs://, hyper://, bittorrent://, and gemini:// alongside http(s).
Terminal Gemini browser written in Go. Tab support, bookmarks, theming; the dominant TUI Gemini client.
W3C's first reference browser, used to develop and demonstrate HTML 3, CSS, and embedded MathML before those landed in production browsers.
Earlier Android Gemini browser. Simpler than Buran; works well on older Android versions.
Original Gemini client from Solderpunk. Python terminal app; spartan and intentionally minimal.
Defunct experimental browser for the peer-to-peer web. Could create, host, and visit websites over the Hypercore Protocol with no servers.
Multi-protocol terminal browser supporting Gemini, Gopher, Finger, local files, and Spartan. Cross-platform Go binary.
Android Gemini browser. Material-design UI; alongside Ariane the main mobile Gemini client.
GTK Gemini/Gopher/Finger browser written in Rust. Single-window, intentionally limited UI.
Tiny GTK-based browser; minimal JS support, focused on fast static HTML. Reborn in 2024 with active maintainers.
Node.js static-site generator. Templating-language-agnostic (Nunjucks, Liquid, Markdown, Pug, EJS), "unopinionated successor to Jekyll" in the JS ecosystem.
Enhanced Links β fork of Links with frame/CSS/JS support and tabs. The most-featureful terminal browser of the 2000s era.
Emacs client for Gopher and Gemini (and Finger). Renders content into Emacs buffers and follows links via mouse or keyboard.
Multi-platform IPFS browser, content explorer, and identity (DID) manager. PyQt-based desktop app for the dweb.
GTK4 native Gemini browser following GNOME HIG conventions. Tabs, history, font-customization.
Curl-like CLI Gemini client + a separate TUI browser. Composable Unix-toolish approach to Gemini.
Fast Go static-site generator. Single binary, extensive theme ecosystem; the de-facto SSG for documentation and engineering blogs.
Brown University's hypertext system β first to demonstrate "webs" of typed bidirectional links spanning documents and applications. Influence on early HTTP/HTML design via Brown alumni; abandoned when A/UX support disappeared.
The first popular static-site generator, by Tom Preston-Werner (GitHub co-founder). Powered GitHub Pages and put SSGs into the mainstream developer workflow.
Qt-based Gemini/Gopher/Finger browser. Archived in 2022 but still functional; Lagrange has largely absorbed its mind-share.
Independent browser engine spun out of SerenityOS. Single-process tab-isolated architecture, written entirely from scratch. Aims for a 2026/2027 alpha.
Beautiful native Gemini/Gopher/Spartan/Titan/Finger client with mobile and desktop versions. The most polished small-web browser by a wide margin.
Firefox fork with telemetry stripped, sensible privacy defaults, and arkenfox-style hardening baked in.
Text and graphical browser from MikulΓ‘Ε‘ PatoΔka (also LVM, JFS-fuse). The graphical mode rendered web pages on framebuffer/svgalib without X.
Text-mode web browser from the University of Kansas. Still useful in 2025 for screen-reading the web, scripted scraping, and accessibility testing.
Joint Mullvad+Tor Project effort: Tor Browser's anti-fingerprinting work without the Tor network β meant to pair with Mullvad VPN or any other connection.
The first widely-popular graphical web browser. Andreessen's NCSA team's work that made the web a consumer-visible medium; Netscape was the commercial successor.
Independent, lightweight HTML browser with its own rendering engine. Runs on low-resource systems and exotic OSes (RISC OS, Haiku, AmigaOS).
Doug Engelbart's NLS β the system demoed at "The Mother of All Demos" (1968): hypertext, multi-user collaboration, shared screen, mouse. Commercialized as Augment by Tymshare; conceptually decades ahead of its time.
Firefox extension adding Gopher protocol support back after Mozilla removed the built-in client. From Floodgap; updated periodically through the WebExtensions transition.
Minimal peer-to-peer web browser with first-class support for ipfs://, hyper://, web3://, and ipns:// protocols alongside http(s).
Python static-site generator. Markdown/reStructuredText input, theme system, plugin ecosystem.
Experimental Rust-based browser engine. Birthed Rust's async story and parts of Firefox's Stylo CSS engine. Picked up by Linux Foundation after Mozilla cut funding.
Terminal Gemini browser by Omar Polo (also gmid). Heavy Emacs-flavored key bindings; supports Gopher and Finger.
Firefox-ESR fork that routes all traffic through Tor and normalizes browser fingerprints. The reference client for browsing the open web anonymously.
Terminal Gopher client by Solderpunk (also Gemini's designer). Single-file Python; the ancestor of AV-98.
Terminal browser that displays tables and images (in graphical terminals!). Long the favored text-mode browser in Japan and among Emacs users.
The original web browser, by Tim Berners-Lee on NeXTSTEP. Was also a WYSIWYG editor β that side took thirty years to come back into fashion.