Mastodon

microblogging · live · since Oct 2016

People post short messages with images, video or polls, follow people and hashtags across the fediverse, and reply, boost and quote in a chronological feed. The row is Mastodon as its makers serve it, through mastodon.social, mastodon.online and the official apps.

how dependent?

  1. 07OperatorDEMastodon GmbH
  2. Owner?Not established
  3. ProtocolINTW3C
  4. Shared services–None
  5. CodeDEMastodon GmbH
  6. Verification–None
  7. 06ModelsDEDeepL
  8. 05DataEUMastodon GmbHUSPostmark
  9. 04ServersDEHetznerFROVHcloud
  10. EdgeUSFastly
  11. 03–01Belowcompute, networks and resources are not recorded per app

Every layer above links to what it rests on. The figure counts the EU, the EEA, Switzerland and the UK as European, as the landscape does.

How it is run

nine questions
ArchitectureWho holds your account and posts?

Federated

open protocol: yes

move your account and keep your followers: yes

hub: none

Posts travel over ActivityPub, a W3C Recommendation that other fediverse software also implements. A moved account takes its followers with it automatically, but its posts stay on the old server. No single company's servers are needed, and mastodon.social is one of about 7,400 Mastodon servers that joinmastodon.org counts.

Business modelWho pays, and for what?

Donations · grants · subscriptions

Donations are the largest disclosed source, with €337k from individual donors between September 2024 and September 2025, plus large gifts such as €2.2M from the Atwood family. Public money comes from a €614k Sovereign Tech Fund service agreement (2026) and an NGI0 Commons Fund grant through NLnet. Since 2025 Mastodon GmbH has also sold managed Mastodon servers to organisations (coded as subscriptions), with undisclosed revenue, so the order is inferred from the disclosed amounts.

OrganisationWhat kind of organisation runs it?

Not established

control: Not established: Mastodon GmbH (Berlin, for-profit) has a single shareholder that free register data does not name, and the Belgian non-profit (AISBL) meant to become its parent has no public record yet

Mastodon describes itself as a non-profit and takes donations through Mastodon, Inc. (a US 501(c)(3)) and the German fiscal sponsor WE AID. But the company that runs it lost its charitable status, and the AISBL that is to own it had no public record as of September 2026, so what kind of organisation holds Mastodon is not established. A new shareholder list was filed on 14 November 2025, when the founder was paid €1M for the brand and assets; as a GmbH it could legally be sold.

FeedWho decides what you see?

Newest first

The home feed shows posts from the accounts and hashtags a user follows, in chronological order and unranked. A separate Trending tab lists popular posts, but it is not the home feed.

ModerationWho moderates?

Each server's admins

Each server's admins set and enforce their own rules. Mastodon GmbH moderates mastodon.social and mastodon.online under their server rules, and other servers moderate their own users. Mastodon plans to add service rules and a DSA moderation and appeals section to its terms in December 2026.

AI trainingDoes your content train AI?

Ruled out

Mastodon says it does not use AI and does not sell data, and the mastodon.social terms license content only to operate the service. Opt-out does not apply. On scraping by others, the terms in force since 31 August 2026 drop the 2025 ban on scraping for LLM training, and robots.txt blocks only OpenAI's GPTBot (observed).

IdentityMust you prove who you are?

No ID needed

verification: none

Read off the verification layer, where its sources are.

Open sourceIs the code open?

Open source

licence: AGPL-3.0-or-later (server); GPL-3.0 (official apps)

Read off the code layer, where its sources are.

SizeHow big is it?

721.1k a month worldwide

counted: monthly active users, worldwide

period: 28 Sep 2026

Monthly active users across all Mastodon servers, from Mastodon's own crawl of the 7,421 servers it could reach on 28 September 2026. mastodon.social, the server Mastodon GmbH runs, counts 269,121 accounts active in the past four weeks, and mastodon.online 7,858. No DSA Art. 24(2) EU figure was found.

What each layer rests on

checked 24 Sep 2026
07OperatorWho serves the app?

Mastodon GmbH · Germany

Berlin, HRB 230086 B. A for-profit company since it lost its charitable status; led by Felix Hlatky and Marius Rothermund. Eugen Rochko stepped down as CEO in November 2025. Fundraising goes through Mastodon, Inc. (a US 501(c)(3)) and WE AID gGmbH (DE).

07OwnerWho owns the operator, where someone else does?

Not established

Not established. The planned Belgian non-profit parent has no public record as of September 2026. In November 2025 Mastodon said its US 501(c)(3) would hold the trademark and other assets until then, but the August 2026 trade mark policy names Mastodon GmbH. The register lists a single shareholder whose identity is behind a paywall.

07ProtocolWho writes the rules of the network?

W3C · international

protocol: ActivityPub

A W3C Recommendation since January 2018, now maintained by the Social Web Working Group, which Mastodon GmbH joined in 2026. The W3C has been incorporated in the US as a non-profit since 2023; it is coded here as an international body.

07Shared servicesWhat does it lean on but not run?

None

07CodeWho builds the software?

Mastodon GmbH · Germany

licence: AGPL-3.0-or-later (server); GPL-3.0 (official apps)

repository

Built by Mastodon GmbH staff and outside contributors, and hosted on GitHub.

07VerificationWho checks users' identity, age or account?

None

ID needed to post: no

An email address and a self-declared date of birth (16+). Profile verification is an optional check on a linked website, and needs no documents.

06ModelsWhose models moderate, rank or check?

DeepL · Germany

Mastodon says it does not use AI, and reports are handled by people alone. Posts can be machine-translated on request; the provider isn't named, and DeepL is inferred from the language codes the server returns.

05DataWhere does the data sit?

Mastodon GmbH · European Union

also Postmark · United States: transactional email, named in the terms

where: The EU, according to the help centre. The mastodon.social privacy policy is the software's unedited default template, so it names no controller, location or processors. The terms name Mastodon GmbH as controller.

transfers: Not disclosed. Email goes through Postmark, whose servers are in the US; company mail is on Google (observed). Federated posts are copied to the other servers that receive them.

04ServersWho runs the servers?

Hetzner · Germany

also OVHcloud · France: second hosting sub-contractor named in the terms

The web and media hosts sit behind Fastly, but the streaming host answers directly from Hetzner.

  • mastodon.social terms of serviceWe may use sub-contractors to perform our obligations under these terms (e.g., Hetzner, OVHcloud, Postmark).read 24 Sep 2026
  • measured · streaming.mastodon.social · AS24940 Hetzner · 24 Sep 2026 · the WebSocket streaming API, not behind the CDN
04EdgeWho stands in front of them?

Fastly · United States

Fastly also appears among Mastodon's in-kind sponsors.

  • joinmastodon.org, sponsorsread 24 Sep 2026
  • measured · mastodon.social · AS54113 Fastly · 24 Sep 2026
  • measured · files.mastodon.social · AS54113 Fastly · 24 Sep 2026 · media
  • measured · mastodon.online · AS54113 Fastly · 24 Sep 2026

Checked 24 Sep 2026.