* :heavy_check_mark: **[Aardwolf](https://github.com/Aardwolf-Social/aardwolf)** ([site](https://aardwolf.social)): Facebook-like social network connecting communities across the web `AGPL-3.0, Rust`
* :heavy_check_mark: **[Dolphin](https://github.com/syuilo/dolphin)**: Lightweight ActivityPub Server optimized for single-user. A fork and sister project of Misskey `AGPL-3.0, Javascript`
* :tada: :heavy_check_mark: **[Epicyon](https://code.freedombone.net/bashrc/epicyon)** ([site](https://epicyon.net)): ActivityPub server implementing S2S and C2S protocols, suitable for single board computers. Includes features such as moderation tools, post expiry, content warnings, and image descriptions `AGPL-3.0, Python`
* :tada: :heavy_check_mark: **[Friendica](https://github.com/friendica/friendica)** ([site](https://friendi.ca)): Personal network that helps to keep in contact with friends. Interface and functionality include common features of a mainstream social network `AGPL-3.0, PHP`
* :tada: :heavy_check_mark: **[groundpolis](https://github.com/xeltica/groundpolis)**: A microblogging service forked from Misskey `AGPL-3.0, Typescript`
* :tada: :heavy_check_mark: **[Honk](https://humungus.tedunangst.com/r/honk)** ([Fedi account](https://honk.tedunangst.com/u/tedu)): ActivityPub server with minimal setup and support costs `ISC, Go`
* :tada: :heavy_check_mark: **[Mastodon](https://github.com/tootsuite/mastodon)** ([site](https://joinmastodon.org)): Epic microblogging network with many features and multiple interface layouts to choose from `AGPL-3.0, Ruby`
* :heavy_check_mark: **[microstatus](https://github.com/Arkanosis/microstatus)**: Lightweight Mastodon and GNU Social-compatible server implementation `ISC, Rust`
* :tada: :heavy_check_mark: **[Misskey](https://joinmisskey.github.io)** ([site](https://joinmisskey.github.io)): Sophisticated microblogging with personality. Provides many additional features like calendar, emoji reactions, polls, games, and many other widgets `AGPL-3.0, Javascript`
* :black_nib: :heavy_check_mark: [**Mistpark 2020**](https://codeberg.org/zot/misty/) aka 'misty' ([site](https://zotlabs.com/misty), [Fedi account](https://z.macgirvin.com/channel/mike)) - A webserver app that supports AP and Zot protocols, fork of Zap `CC0-like, PHP`
* :tada: :heavy_check_mark: **[Smithereen](https://github.com/grishka/Smithereen)**: VKontakte-like social network, with friends, walls, photo albums and groups `Unlicense, Java`
* :tada: :heavy_check_mark: **[SocialHome](https://git.feneas.org/socialhome/socialhome)** ([site](https://socialhome.network)): Personal webpage with social networking functionality `AGPL-3.0, Python`
* :tada: :heavy_check_mark: **[Tavern](https://gitlab.com/ngerakines/tavern/-/tree/release-amber-ale)** ([Fedi account](https://mastodon.social/@ngerakines)): A minimalistic Activity Pub server. Think Mastodon, but smaller and with fewer features `Go, MIT`
* :tada: :heavy_check_mark: **[Zap](https://codeberg.org/zot/zap)** ([site](https://zotlabs.com/zap/), [Fedi account](https://z.macgirvin.com/channel/mike)): A webserver app that supports AP and Zot protocols `CC0-like, PHP`
* :heavy_check_mark: **[pubgate](https://github.com/autogestion/pubgate)**: Lightweight ActivityPub CMS. Implements both client-to-server (C2S) and server-to-server(S2S) APIs. Compatible with Mastodon, Pixelfed, Pleroma and microblog.pub. `BSD-3-clause, Python`
* :heavy_check_mark: [**Spritely**](https://gitlab.com/spritely) ([Fedi account](https://octodon.social/@cwebber)): Research space for a next-gen distributed social network written in Racket and consisting of multiple projects, by AP specification co-author Christopher Lemmer Webber. `Apache-2.0, Racket`
* :black_nib: **[Diffu](https://mockup.diffu.social)**: an attempt at a federated Tumblr/ Medium, aimed at hosting long form articles that easily and neatly embed other kinds of content from any fediverse platform (microblog posts, PixelFed images, PeerTube videos etc). Proposed by a French company called Befox, who attempted to crowdfund development (inspired perhaps by the success or PeerTube and Mobilizon), but didn't hit their target.
* :heavy_check_mark: **[Hubzilla](https://framagit.org/hubzilla)** ([site](https://hubzilla.org)): CMS with a range of groupware tools available as plug-ins `MIT, PHP`
* :heavy_check_mark: **[Little Library](https://github.com/Alamantus/little-library)**: A digital give-a-book, take-a-book library for ebooks. `AGPL-3.0, Javascript`
* :black_nib: **[picopub](https://github.com/transitracer/picopub)**: Created by the developer of Fontina as a "tiny, Mastodon-compatible blog"; no commits since February 2019
* :heavy_check_mark: **[Read.as](https://github.com/writeas/Read.as)** ([site](https://read.as)): Reading app by the devs of WriteFreely `AGPL-3.0, Go`
* :heavy_check_mark: **[WordPress](https://git.feneas.org/feneas/fediverse/-/wikis/Wordpress-integration-with-Fediverse)** - [listed as a project on the-federation.info](https://the-federation.info/wordpress). [AP plug-in](https://wordpress.org/plugins/activitypub) by @pfefferle@mastodon.social, that allows users on AP apps to follow WP blogs, and comment on them, from an AP app.
* :black_nib: **[Flarum](https://github.com/squeevee/flarum-ext-feddle)**: Experimental plugin for [Flarum](https://flarum.org/) forum software by [@squeevee](https://yiff.life/@squeevee/102496777538790361)
* :black_nib: **[FediQuest](https://shapegoal.org/matejlach/fediQ-server)** ([site](https://shapegoal.org)): A federated alternative to traditionally centralized question & answer platforms, such as Quora/StackOverflow. `GPL-3.0, Go`
* :heavy_check_mark: **[Lemmy](https://github.com/dessalines/lemmy)**: Link aggregator, by [@LemmyDev](https://mastodon.social/@LemmyDev/102106696961226378) `AGPL-3.0, Rust`
* :heavy_check_mark: **[Smilodon](https://source.puri.sm/liberty/host/smilodon)**: the server by Purism used in LibreOne, not the abandoned Tuxcraft server or Pylodon client; a complementary fork of Mastodon, focusing on opt-in public spaces `AGPL-3.0, Ruby`
* :black_nib: **[Marmota](https://gitlab.com/Nefix/marmota/issues?label_name=ActivityPub)**: Streaming service like Spotify, no commits since March 2019;
* :heavy_check_mark: **[Gath](https://github.com/lowercasename/gathio)**: Public events with no registration required, an instance connected with the friend.camp Mastodon instance is up at: http://events.friend.camp `GPL-3.0, Javascript`
* :heavy_check_mark: **[Mobilizon](https://framagit.org/framasoft/mobilizon)** ([site](https://joinmobilizon.org/en), [Fedi account](https://framapiaf.org/@mobilizon)): Aims to be more than a Meetup clone `AGPL-3.0, Elixir`
Friendica (see above) has an [events engine that federates events over AP](https://socialhub.activitypub.rocks/t/activitypub-at-36c3-the-decentral-assembly-and-fediverse-party/402/5) and is looking to test interop with other AP events apps. [NextCloud federated events](https://github.com/nextcloud/calendar/pull/878) are in the works but this [may or may not be AP-compatible](https://github.com/nextcloud/server/issues/1440).
* **[MoodleNet](https://gitlab.com/moodlenet)**: [Social client for Moodle](https://moodle.com/moodlenet) LMS (Learning Management System) aimed at helping teachers collaboratively collate and curate sets of OER (Open Educational Resources)
* :heavy_check_mark: **[OLKi](https://framagit.org/synalp/olki/olki/-/wikis/ActivityPub-dialect-documentation)** ([site](https://olki.loria.fr/platform), [Fedi account](https://mastodon.etalab.gouv.fr/@scifed)): A self-hosted linguistic corpora exchange platform that aims to be a simple gateway to the Fediverse for scientific interaction `AGPL-3.0, Python`
* :heavy_check_mark: **[SkoHub](https://github.com/hbz/skohub-pubsub)** ([site](https://skohub.io)): Creates a publication / subscription infrastructure for Open Educational Resources. It allows to follow specific subjects and to be notified when new content about that subject is published. `Apache-2.0, Javscript`
* :heavy_check_mark: **[CPub](https://gitlab.com/openengiadina/cpub)**: a semantic web server, implements a Linked Data Platform (LDP), uses RDF Turtle as serialization format, part of the [openEngiadina](https://openengiadina.net) project `AGPL-3.0, Elixir`
* :heavy_check_mark: **[SemApps](http://www.virtual-assembly.org/semapps-2/)** ([site](http://semapps.org/?PagePrincipale&lang=en)): A collaborative, generic knowledge management system. Aims to ease data storage and filtering. `Apache-2.0, Javascript`
#### Reviewing
* :heavy_check_mark: :tada: [**Bookwyrm**](https://github.com/mouse-reeve/bookwyrm) ([site](http://fedireads-test.glitch.me)): A federated alternative to Goodreads `CC0-1.0, Python`
* [**Learn Awesome**](https://github.com/learn-awesome/learn): Open-source equivalent review aggregation site. Think GoodReads, but generalized to all learning resources organized by topics, formats and difficulty. `AGPL-3.0, Ruby`
* :heavy_check_mark: **[Readlebee](https://gitlab.com/Alamantus/Readlebee)** ( [Fedi account](https://floss.social/@Readlebee)): An attempt to create a viable Goodreads alternative, book reading progress, lists, reviews, comments `AGPL-3.0, Javascript`
#### Games
* :heavy_check_mark: [**RavenVale**](https://git.lubar.me/lubar-local/ravenvale): Federating guild website using GuildWars2 API `-, Go`
* :heavy_check_mark: **[castling.club](https://github.com/stephank/castling.club)** ([site](https://castling.club/), [Fedi account](https://mastodon.social/@kosinus)): Challenge someone to a game of chess using toots. An ActivityPub server with a single hardcoded King service actor that acts as a chess arbiter. `MIT, Typescript`
* :tada: :heavy_check_mark: **[Guppe](https://github.com/wmurphyrd/guppe)** ([site](https://gup.pe)): By [@datatitian](https://social.coop/@datatitian/102837577105371476), adds "groups" support as group-type actors `GPL-3.0, Javascript`
* :black_nib: **[Hash2Pub](https://socialhub.activitypub.rocks/t/about-hash2pub/543)**: A fully-decentralised relay for global hashtag federation. [White paper](https://git.orlives.de/schmittlauch/paper_hashtag_federation). No source code available yet.
* :black_nib: **[Life-Server](https://github.com/interop-alliance/life-server)**: [Homepage](https://permanent.cloud/apps/life-server), "A decentralized personal data server inspired by MIT's Solid Project ... Since node-solid-server (NSS) is being deprecated in favor of inrupt/pod-server, this repo intends to be another compatible implementation", `MIT, Nodejs`
* :black_nib: **[un chapeau](https://gitlab.com/marnanel/un_chapeau/-/issues/17)**: Server for the Mastodon protocol, implemented in Django. `AGPl-3.0, Python`
Projects that seem dormant and may be dead, but may also be doing dev quietly in private, or have moved to a new code forge without leaving a forwarding address, etc. Any information that could help us clarify whether these projects are still alive would be much appreciated.
* **[Anancus](https://gitlab.com/tuxether/anancus)**: By [@tuxether](https://floss.social/@tuxether), Link aggregator, [discontinued](https://gitlab.com/tuxether/anancus/issues/2)?
* :heavy_check_mark: **[reel2bits](https://github.com/rhaamo/reel2bits)** ([site](https://reel2bits.org)): Music and podcast hosting, `AGPL-3.0, Python`
Projects that are officially abandoned by the maintainers or with no signs of life on their code repo or any other official channels for more than a year. Listed on this watchlist just in case anyone doesn't realize they're dead, and thinks we just didn't know about them. Also in case a project is orphaned, then reactivated by a new developer.
* [ActivityPub.jl](https://github.com/Matt5sean3/ActivityPub.jl) - AP support in the Julia language by [@Matt5sean3](https://rva.party/@Matt5sean3), no commits since August, 2018. Project is [missing, presumed dead](https://github.com/Matt5sean3/ActivityPub.jl/issues/1).
* [Calendar-social](https://gitea.polonkai.eu/gergely/calendar-social/) - was definitely planning to [implement AP](https://gitea.polonkai.eu/gergely/calendar-social/issues/122). Missing, [presumed discontinued](https://gitea.polonkai.eu/gergely/calendar-social/issues/123)
* [CloutStream](https://web.archive.org/web/20180808152307/http://cloutstream.com/) - proposed by [@mwpdx](https://mstdn.io/@mwpdx/100591379202470027) as a federated replacement for LinkedIn. Both @cloutstream and @mwpdx Mastodon.social accounts appears to have been removed from the server, all the project tools appear to be down, or removed from the host.
* [Fontina](https://github.com/beta-phenylethylamine/fontina) - proposed as a photo-sharing social media network. GH repo has gone read-only, and now says "dead project".
* [GangGo](https://git.feneas.org/ganggo/federation/issues/17) - Seems to have settled on using [Go-Fed for AP federation](https://git.feneas.org/ganggo/activity). Developer has suspended development for the foreseeable future.
* [Numa](https://github.com/numaverse/numaverse-gateway/issues/3) - built on Ethereum blockchain but intended to federate with AP. No commits since April 2018. No reply on issue about AP compatibility testing from May 8. Homepage now a spam site.
* [Osada](https://framagit.org/zot/osada) - Osada was a full featured social network application running under the ActivityPub protocol. It also communicated with and inter-operated with servers on the Zot6 network. Abandoned by the developers in March 2019 (**Update**: Recent activity Aug 2020, moved to [Codeberg](https://codeberg.org/zot/osada)).
* [Pylodon](https://github.com/rowanlupton/pylodon) - Flask-based (Python) ActivityPub server , [source code also on GitLab](https://gitlab.com/rowanlupton/pylodon), no updates on either repo for about a year, nor on their [Smilodon client app](https://github.com/rowanlupton/smilodon).
* [Quit.im](https://quit.im) - this was a photo-sharing web client for a GNU social server, rather than a completely separate app. It would become an AP implementation when the AP plug-in for GS is done, but it's been obsoleted by the release of PixelFed.
* [Smilodon](https://gitlab.com/tuxcrafting/smilodon) (server by Tuxcraft) - abandoned by developer "I'm now [working on Sminos](https://gitlab.com/tuxcrafting/sminos/issues/1) and so this will probably be 100% abandoned. There's not much to salvage, its code is cancer." Sminos appears to have never got beyond the initial commits.
Aside from project homepages and issue trackers, and comments made on the fediverse, the [SocialWG has a list](https://www.w3.org/wiki/Socialwg/ActivityPub_network) of projects they hoped would implement ActivityPub and links to issues where it's discussed. Also, there is an [implementation report on ActivityPub.rocks](https://activitypub.rocks/implementation-report/). @Mayel from Social.coop created a [web spreadsheet of AP apps](https://ethercalc.org/fediverse-stacks) and their characteristics. More projects using AP are [profiled on We Distribute](http://wedistribute.org/) by Sean Tilley and his team. There are boards for discussing a range of [AP implementations on the SocialHub forum](https://socialhub.activitypub.rocks/c/software/14). [Alternative.to](https://alternativeto.net/list/5696/activitypub) has a list of AP servers and client apps. The [ActivityPub tag on GH](https://github.com/topics/activitypub) is also a way to discover projects experimenting with AP.
