Decentralized & Federated Social Networks 2026 — Mastodon / Bluesky / Nostr / Lemmy / Pixelfed / PeerTube / Misskey / Sharkey / Threads (ActivityPub) Deep-Dive

Prologue — The People Who Scattered After Twitter

In October 2022, Elon Musk bought Twitter. By July 2023, the company was renamed "X." In between, a lot of people left — and they didn't all go to the same place.

• Journalists, academics, and the people who liked "old Twitter" went to Mastodon.
• People who wanted a bigger interface and "I choose my own algorithm" went to Bluesky.
• The Bitcoin/crypto crowd who believed "the protocol must really be decentralized" went to Nostr.
• People who left Reddit after the 2023 API debacle went to Lemmy and Kbin/Mbin.
• Photographers fed up with Instagram went to Pixelfed, and video creators tired of YouTube went to PeerTube.
• After Twitter API lockdowns, Japanese users moved en masse to Misskey.io.

And in 2024 the biggest event happened: Meta's Threads started connecting to ActivityPub. The 100M+ users of Facebook/Instagram are slowly getting wired into the Fediverse.

This article gives you the entire map in one read.

1. The 2026 Decentralized Social Map — Three Protocols

We say "decentralized social" as one word, but really three completely different protocols are competing.

[ActivityPub] — W3C Recommendation (2018)
   Mastodon · Pleroma · Akkoma · Misskey · Sharkey · Iceshrimp.NET
   Pixelfed · PeerTube · Lemmy · Mbin · Friendica · Threads (partial)
   |
   +-- Biggest and most diverse · The home of the word "Fediverse"

[AT Protocol] — Bluesky (2023+)
   Bluesky app · Various third-party clients
   |
   +-- 30M+ users, single-company operation + protocol opened

[Nostr] — Notes and Other Stuff Transmitted by Relays (2019+)
   Damus (iOS) · Amethyst (Android) · Iris · Coracle · Primal
   |
   +-- Truly decentralized · Bitcoin crowd · Funded by Jack Dorsey

Plenty of people cross-post the same note to all three. But the protocol philosophies are diverging enough that bundling them as "decentralized social" is getting harder.

2. Mastodon (Eugen Rochko) — The OG of ActivityPub

Mastodon is a microblog built in 2016 by Eugen Rochko (@Gargron@mastodon.social), then a 24-year-old developer in Jena, Germany. It grew fast from 2017 onward, and when W3C ActivityPub became a Recommendation in 2018, Mastodon became the de facto standard implementation of the Fediverse.

Why It Became the First Landing Pad

• Oldest ActivityPub implementation on the W3C standard — fewest compatibility issues.
• Moderation is per-instance. Instance admins set their own rules. Don't like them? Move.
• Minimalism without "Quote Toot": deliberately resisted quote-reposts for years (finally added end of 2024). The fear was quote-RT culture breeding dunking.
• Chronological timeline: no algorithmic recommendations. Posts from people you follow, in order.

2025-26 Changes

• November 2024: full move to non-profit (Mastodon gGmbH). Eugen handed over personally-held trademarks and assets to the new non-profit.
• Late 2024 quote-reposts: after years of refusal, finally added. Instance admins can opt in.
• 2025 user stagnation: as Bluesky grew fast, Mastodon's daily-active count dipped slightly. But the core base (journalists, academics, open-source developers) is sticky.

Who Should Pick It

• Users who care about open-source/standards basis
• People who want a chronological feed with no algorithm
• Anyone who agrees with the per-instance moderation philosophy

3. Bluesky (Jay Graber) — AT Protocol, 30M+ Users in 2025

Bluesky started in 2019 as an R&D project Jack Dorsey kicked off inside Twitter. In 2021 it spun out as a separate PBC (Public Benefit Corporation), and in 2022 Jay Graber became CEO and started in earnest.

What Makes AT Protocol Different

The biggest gap from ActivityPub is account portability.

• In ActivityPub, when you move instances your followers come with you, but your posts mostly do not. Your handle changes.
• In AT Protocol, your DID (Decentralized Identifier) is your identity, your PDS (Personal Data Server) holds your data, and an AppView builds the feed. The three are separated, so you move only the PDS and everything follows.

The other differentiator is the algorithm market (Custom Feeds). Users can pick or build feeds like "What's Hot," "Mutuals," "Discover," "Quiet Posters."

2024-25 Explosive Growth

• Feb 2024: open sign-up (no invites). Started around 3M users.
• Right after Nov 2024 US election: 1M+ signups in a single week as users disillusioned with X's policies migrated.
• 2025: crossed 30M. Fast growth in Japan/Korea/Brazil too.
• Monetization begins: from 2025, paid subscription and add-on options under consideration.

Criticisms

• Effectively a single PDS today: 99%+ of accounts live on the bsky.social PDS. Critics call this "decentralizable" not "decentralized."
• No bridge to ActivityPub: the two protocols don't talk to each other. Same user has to maintain accounts on both (except via bridges like Bridgy Fed).

Who Should Pick It

• Mainstream users who want a richer interface (search, trending, algorithm feeds)
• Developers who want to build their own feed algorithms
• Anyone who wants the "old Twitter" picture back

4. Nostr — Damus + Amethyst + Jack Dorsey Funding

Nostr stands for "Notes and Other Stuff Transmitted by Relays." Started in 2019 by the pseudonymous fiatjaf, it suddenly became famous in December 2022 when Jack Dorsey said he liked it more than Bluesky and donated 14 BTC to fund it.

The Nostr Philosophy — Real Decentralization

• Account = a single private key. An npub (public key) / nsec (private key) pair is everything. No signup with a server required.
• Relays are message queues: a user posts the same note to many relays at once. One relay dying doesn't kill the note.
• Clients are free to pick: Damus, Amethyst, Primal, Iris — each reads the same protocol with its own UI.
• Zaps: send satoshi-level tips via the Lightning Network. Tightly bound to Bitcoin.

State in 2025-26

• Active users: estimated 200K-500K (varies wildly by relay). Still smaller than Mastodon/Bluesky.
• Damus: shortly after App Store launch in 2023 it nearly got removed because "Zaps look like payments" — solved by routing Zaps through Safari/external payment. The de facto iOS client.
• Amethyst: Android's de facto client, by Vitor Pamplona.
• Primal: a cache server + client that appeared in 2024. Strong search and algorithmic feeds.

Drawbacks

• Search is hard: by structure, global search across distributed relays is genuinely hard.
• Key management burden: lose your nsec and your account is unrecoverable. Heavy for non-technical users.
• Spam: anyone can publish anything and there's no unified moderation, so spam runs high. Filtering depends on the client.

Who Should Pick It

• Bitcoin/crypto-aligned users
• People who really want censorship-resistant publishing
• Developers interested in protocol aesthetics

5. Lemmy — The Reddit Alternative

Lemmy is an ActivityPub-based link aggregator/forum, the closest clone of Reddit. It started in 2019 but only suddenly mattered in June 2023, when Reddit's API price hike killed third-party apps (Apollo, Reddit is Fun, BaconReader).

The 2023 Reddit API Crisis

• April 2023: Reddit announces the API pricing change.
• June 12-14: massive subreddit blackout. About 8,000 subreddits went private.
• Apollo's developer Christian Selig revealed a roughly 20M-USD-per-year bill. Apollo shut down on July 1.
• During that period Lemmy went from roughly 30K to 200K+ users. lemmy.world became the biggest instance.

2024-26 Today

• Active users: roughly 50K-100K MAU. Down from peak but stable.
• Main communities: tech/open-source/Linux dominated. The vibe of Reddit's r/linux and r/programming carried over best.
• Drama: lemmy.ml (the original developers' instance) drew criticism for political bias, and lemmy.world became the de facto top instance.

Relation to Mbin/Kbin

There's a sibling Reddit-like on top of ActivityPub called Kbin/Mbin (detailed in Section 12). Lemmy and Kbin/Mbin can subscribe to each other's communities over the same ActivityPub network.

6. Pixelfed — Instagram Alternative (2024 Funding)

Pixelfed is an ActivityPub-based photo-sharing platform started in 2018 by Daniel Supernault (Dan Sup). It's the closest Instagram clone.

2024 Funding — The Big Moment

In late 2024, Mozilla and NLnet's NGI Zero funded the formation of the Pixelfed Foundation and mobile app development, around 100K USD. Official mobile apps (iOS/Android) launched for the first time, and user count more than doubled.

Strengths

• Photo-first UX: clean grids, stories, collections — Instagram-like.
• No ads. Algorithmic recommendations are opt-in.
• Auto-strip EXIF: removes sensitive metadata like geolocation by default.
• Mastodon-compatible: it's ActivityPub, so following a Pixelfed account from Mastodon brings the photos into your timeline.

Weaknesses

• "Search-based discovery" like Instagram is weak.
• Mobile apps shipped but aren't yet as polished as Instagram's.

Who Should Pick It

• Photographers/illustrators tired of Instagram's ads/algorithm
• Mastodon users who want a unified ActivityPub workflow for photos

7. PeerTube — The YouTube Alternative

PeerTube is an ActivityPub-based video hosting platform developed since 2018 by the French non-profit Framasoft.

P2P + ActivityPub

PeerTube's twist is WebTorrent (BitTorrent over WebRTC) layered on top of plain ActivityPub. When many people watch the same video at once, viewers share the stream with each other. Instance bandwidth costs go down dramatically.

State in 2025-26

• v6, v7 series: live streaming, transcoding improvements, automatic subtitle generation added.
• Loved by small video creators: lecture channels, vegan/Linux/open-source communities tired of YouTube's ad/moderation policies have settled in.
• Still limited: search is per-instance. Global discovery like YouTube's recommendation algorithm is hard.

Who Should Pick It

• Lecture/open-source channels who want ad-free hosting
• Schools and organizations who want to self-host video

8. Misskey — Japanese-Origin, Reaction-First

Misskey is an ActivityPub microblog started in 2014 by Japanese developer syuilo. While Mastodon clones Twitter, Misskey is closer to "Twitter + Discord + emoji reactions" — a richer UX.

Misskey's Signature Features

• Custom emoji reactions: thousands of emoji to react with instead of plain likes — like Discord.
• Renote + Quote Renote: quote-reposts are native.
• MFM (Misskey Flavored Markdown) : text effects in posts — rotation, shaking, colors, jitter.
• AiScript: run small scripts inside posts (e.g., interactive widgets).

Misskey.io — The Largest Single Fediverse Instance

• Exploded in 2022 when Twitter's API was restricted and Japan's illustrator/otaku community migrated.
• ~200K-300K MAU as of 2024 — the largest single ActivityPub instance.
• The base is Japanese illustrators, VTuber fans, gamers. Korean and English users are also significant.

Drawbacks

• Heavy load: reactions, MFM, and AiScript make the client heavy. Battery drain on mobile.
• Moderation: Japanese expression-policing norms and Western moderation norms often clash.

9. Sharkey / Iceshrimp.NET — Misskey Forks

Misskey started as syuilo's personal project, so users who disagreed with its direction forked it.

Sharkey

• Origin: forked around 2023 by the transfem.dev community.
• Lead: Marie / the Sharkey team.
• Differences: keeps Misskey's UX, but adds stronger moderation tools, LGBTQ+-friendly defaults, extra security features.
• Used by: transfem.dev and 100+ other instances run Sharkey.

Iceshrimp.NET

• Origin: spiritual successor after Firefish (formerly Calckey) died.
• Language: rewritten in .NET / C# instead of the original TypeScript/Node. Much lower memory footprint and better performance.
• Used by: small instances and operators who want lower overhead.

10. Firefish RIP 2024 — Calckey Rebrand, Then Death

The short, sad story of Firefish.

Timeline

• 2022: Calckey forks from Misskey. Lead developer: ThatOneCalculator (Kainoa Kanter).
• June 2023: user count explodes right after the Reddit API crisis.
• August 2023: rebrand to Firefish. Reason: "Calckey" was hard to pronounce and hard to search.
• March 2024: ThatOneCalculator announces stepping down as maintainer. Burnout, lack of funding, team friction.
• Late 2024: development effectively stops. Existing instances migrate to Sharkey or Iceshrimp.NET.

Why It Died

• Single-maintainer burnout: the common pattern of open-source projects.
• No funding model: Patreon/OpenCollective couldn't cover a full-time person.
• The forks moved faster: Sharkey grew around its LGBTQ+ community, Iceshrimp.NET around performance — each found a niche.

Firefish's death convinced everyone in the Fediverse how dangerous single-maintainer dependence is.

11. Pleroma / Akkoma / Friendica / Diaspora — The Rest

ActivityPub has more than Mastodon and Misskey.

Pleroma

• Started: 2017 by lain (pseudonym).
• Language: Elixir/Erlang. Much lower memory use than Mastodon.
• Position: lightweight Mastodon alternative for small-instance operators.
• Drama: certain instances ran with effectively no moderation and a far-right vibe, splitting the project's reputation.

Akkoma

• Started: 2022 fork of Pleroma.
• Reason: users disagreeing with Pleroma's main team's direction wanted more proactive moderation tools and UX improvements.
• Lead: floatingghost.

Friendica

• Started: 2010 (originally "Mistpark," rebranded to Friendica in 2012).
• Feature: speaks not only ActivityPub but also Diaspora protocol, OStatus, RSS — a "protocol polyglot."
• Today: small user base but stable.

Diaspora

• Started: 2010 by four NYU students (Maxwell Salzberg, Daniel Grippi, Raphael Sofaer, Ilya Zhitomirskiy). Big hype as a Facebook alternative.
• Today: uses its own Diaspora Protocol separate from ActivityPub. Limited compatibility with the rest of Fediverse.
• State: user count effectively flat. A small active community persists.

12. Mbin (Kbin Successor) — Lemmy Competitor

From Kbin to Mbin

• August 2022: Polish developer Ernest Wiśniewski starts Kbin — an ActivityPub-based Reddit/Hacker News clone.
• June 2023: kbin.social explodes during the Reddit API crisis.
• Early 2024: Ernest's personal health/time issues stall Kbin development.
• Around May 2024: community forks Mbin.
• Late 2024 - 2025: Mbin becomes the de facto successor. New features, security patches, moderation tools.

Lemmy vs Mbin

Mbin combined a link aggregator + microblog in a single interface. Same ActivityPub network, so Mastodon users can subscribe to Mbin magazines.

13. Element / Matrix — Decentralization of Chat

Matrix is a decentralized chat protocol started in 2014. It's chat (a Slack/Discord/IRC alternative) rather than microblog, so it sits a bit aside from the rest, but it's part of the same "decentralized social" wave.

State in 2025-26

• Matrix 2.0: bundled in 2024 — Sliding Sync, Native OIDC, faster initial sync.
• E2EE by default: end-to-end encryption is the default for both 1:1 and group chats.
• Government/enterprise adoption: France's Tchap, Germany's BwMessenger run on Matrix.
• Still small in consumer: against the giant footprint of Discord/Slack, Matrix is still niche.

Who Should Pick It

• Companies/orgs that need self-hosted chat infrastructure
• Communities that require end-to-end encryption
• Operators uncomfortable with Discord's Trust & Safety policies

14. Threads (Meta) — Gradual ActivityPub Integration 2024-25

The biggest story comes last. Meta's Threads is wiring into ActivityPub.

Timeline

• July 2023: Threads launches. 100M signups in 5 days. Instant signup via your Instagram account.
• March 2024: ActivityPub beta starts. Only some users in the US/Canada/Japan can enable it. Initially one-way ("show my posts on the Fediverse").
• June 2024: expansion worldwide. Mastodon users can follow Threads accounts.
• Late 2024: partial two-way. Threads users can see replies from Mastodon users.
• 2025: more features (replies, likes, notifications) are being integrated.

Why It Matters

• Scale: Threads grew to roughly 300M MAU by 2025. Even a slice of that connected to ActivityPub changes the Fediverse's order of magnitude.
• Meta's commitment: there's regulatory pressure underneath — the EU's Digital Markets Act forces Meta to enable users to take their accounts and data to other servers.
• Pushback: parts of the Fediverse (especially moderation-heavy leftist instances) preemptively defederated from Threads, suspicious of "Embrace, Extend, Extinguish" (the Fedipact movement).

Real Integration or Mock-Up?

Today (late 2025):

• You can search and follow Threads accounts from Mastodon.
• The reverse direction — Threads users seeing Mastodon content — is expanding gradually.
• DMs, video, and some media don't bridge yet.

Full two-way ActivityPub compatibility is the target for late 2026 or 2027.

15. AT Protocol vs ActivityPub — A Difference Analysis

These two protocols solve the same problem — decentralized social — differently.

Will They Meet?

Today, no. Bridgy Fed and similar third-party bridges connect ActivityPub and AT Protocol partially, but there is no official integration.

• ActivityPub camp: "We were the standard first. Real decentralization is instance diversity."
• AT Protocol camp: "ActivityPub's account-migration model is broken. Ours is the real user-owned model."

The debate will continue through 2026-27. In practice, many users just keep accounts on both and cross-post.

16. Korea — Korean Mastodon Instances

Korea's Fediverse is small but active.

Meari (mastodon.meo.world / formerly meowmeow.kr)

• A Korean-language-centric Mastodon instance.
• "Meari" comes from the Korean word for "echo."
• Hundreds of active users. Illustrators, otaku, Twitter migrants are the core.

Mavicure (mabicure.com)

• Another Korean-language Mastodon instance.
• Centered on gaming/hobby communities.

Other

• planet.moe — English-language instance with some Korean users.
• Many Korean users keep accounts on Misskey.io (Japan) or mastodon.social (the global mainline).
• Bluesky Korean users have grown fast since late 2024. As a single global PDS, there's no separate Korean instance.

17. Japan — Misskey.io, mstdn.jp, Pawoo

Japan has one of the highest Fediverse usage rates in the world.

Misskey.io

• The largest single ActivityPub instance. MAU estimated 200K-300K.
• Operated by MisskeyHQ. syuilo is the core developer.
• Users: illustrators, VTuber fans, otaku, gamers.

mstdn.jp

• Japan's flagship Mastodon instance. Started in 2017 by Sakura Internet — operator changed since.
• A more general Japanese-speaking user base.

Pawoo

• A Mastodon instance launched in April 2017 by Pixiv, illustrator-focused.
• Sold to Russell.Cloud in July 2019 — Pixiv stepped away from operations.
• Still running, smaller than at peak.
• Expression-rule clashes: some non-Japanese Mastodon instances have defederated Pawoo over moderation differences.

Fedibird

• Fedibird.com. A Mastodon fork by Japanese developer noellabo. Adds enhanced search, quote-reposts, and more.

18. Who Should Pick What

Final by-user-type recommendations.

General User — "I want something like Twitter"

• First pick: Bluesky. Easiest signup, most familiar interface.
• Second pick: Threads. If you have an Instagram account, just start.
• Third pick: Mastodon (mastodon.social) . If you want a quieter, algorithm-free vibe.

Developers / Open-Source Crowd

• Mastodon (fosstodon.org, hachyderm.io). The most fellow developers.
• Lemmy (programming.dev) — for technical discussion.
• Bluesky is growing too — being open-source itself draws many.

Artists / Illustrators

• Pixelfed — photo portfolios.
• Misskey.io (Japan / illustrator-centric community) or a Sharkey instance.
• Bluesky + a Custom Feed ("art feed") is also a good pick.

Video Creators

• PeerTube (self-hosted or framatube.org).
• Often mirrored alongside a YouTube channel.

Bitcoin / Crypto Crowd

• Nostr (Damus / Amethyst / Primal).
• The only protocol where you can receive Zaps directly.

Organizations That Need Chat

• Element / Matrix — self-hosted alternative to Slack/Discord.

Political Asylum / Censorship Resistance

• Nostr is the most censorship-resistant.
• Mastodon (your own instance) is also a strong choice.
• Bluesky is weak in this use case due to single-PDS dependency.

19. References

• W3C ActivityPub Recommendation — https://www.w3.org/TR/activitypub/
• Mastodon — https://joinmastodon.org/
• Eugen Rochko (Gargron) — https://mastodon.social/@Gargron
• Bluesky — https://bsky.app/
• Bluesky PBC — https://bsky.social/about
• AT Protocol — https://atproto.com/
• Jay Graber on AT Protocol — https://bsky.social/about/blog
• Nostr — https://nostr.com/
• Nostr Implementation Possibilities (NIPs) — https://github.com/nostr-protocol/nips
• Damus — https://damus.io/
• Amethyst — https://github.com/vitorpamplona/amethyst
• Primal — https://primal.net/
• Lemmy — https://join-lemmy.org/
• Pixelfed — https://pixelfed.org/
• Pixelfed Foundation funding (Mozilla/NLnet) — https://pixelfed.org/blog
• PeerTube — https://joinpeertube.org/
• Framasoft — https://framasoft.org/
• Misskey — https://misskey-hub.net/
• Misskey.io — https://misskey.io/
• Sharkey — https://joinsharkey.org/
• Iceshrimp.NET — https://iceshrimp.dev/
• Firefish (archived) — https://joinfirefish.org/ (no longer active)
• Pleroma — https://pleroma.social/
• Akkoma — https://akkoma.social/
• Friendica — https://friendi.ca/
• Diaspora — https://diasporafoundation.org/
• Mbin — https://joinmbin.org/
• Kbin (legacy) — https://kbin.social/
• Matrix — https://matrix.org/
• Element — https://element.io/
• Threads (Meta) — https://www.threads.net/
• Threads + ActivityPub announcement — https://about.fb.com/news/2024/03/threads-fediverse-test/
• Bridgy Fed — https://fed.brid.gy/
• Fedipact — https://fedipact.online/
• mstdn.jp — https://mstdn.jp/
• Pawoo — https://pawoo.net/
• Fedibird — https://fedibird.com/

In 2026, decentralized social is in an era of "the protocols split" more than "one wins." ActivityPub's diversity, AT Protocol's scale, and Nostr's purity each grow on their own track, and increasingly users keep accounts on two or three at once rather than choosing one. For the foreseeable future, no single place will be "the answer."