Mastodon

Mastodon is a German open-source microblogging platform built on the ActivityPub federation protocol — the W3C standard that enables independent servers to communicate freely. Instead of a single company controlling everything, thousands of independent Mastodon instances connect into a global network where users on one server can follow, reply to, and interact with users on any other.

Each instance sets its own moderation rules, community focus, and data policies. Mastodon gGmbH, the non-profit behind the flagship mastodon.social server, develops the open-source software freely available for any individual or organisation to run. Posts, follows, and interactions federate across instances — and also reach users on Pixelfed, PeerTube, Misskey, and other ActivityPub-compatible platforms.

Key benefits:

• Decentralised federation — no single point of control, censorship, or failure
• ActivityPub standard for interoperability across the entire Fediverse ecosystem
• Chronological feed — no engagement-optimising algorithm by default
• No ads, no tracking, no data monetisation on non-commercial instances
• Per-instance moderation — each community enforces its own rules independently
• Open-source (AGPL) — self-host your own instance with full administrative control
• Rich media posts — images, video, audio, polls, and content warnings up to 500 characters

Mastodon is developed by Mastodon gGmbH, a non-profit based in Berlin, Germany, operating under German law and GDPR. Self-hosted instances can run in any EU jurisdiction, keeping user data entirely within European legal frameworks and free from U.S. platform control.

Founded by Eugen Rochko in 2016, Mastodon hosts millions of users across thousands of independent instances — the largest federated alternative to centralised social networks.