head to head · open source
Mastodon vs Smithereen
Mastodon has 50,299 GitHub stars, 7,498 forks, 4,525 open issues and last shipped yesterday. Smithereen has 546 stars, 36 forks, 44 open issues and last shipped yesterday. Mastodon leads on adoption by 9,112% (50,299 vs 546 stars). Mastodon is written in Ruby under AGPL-3.0; Smithereen is written in Java under Unlicense. Mastodon has attracted 15% as many forks as stars, Smithereen 7%. Mastodon was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (activitypub, fediverse), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Mastodon | Smithereen | |
|---|---|---|
| GitHub stars | ★ 50K | ★ 546 |
| License | AGPL-3.0 | Unlicense |
| Written in | Ruby | Java |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 7.5K | ⑂ 36 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Mastodon if
- You weight community size — 50K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches Ruby
- You value the larger contributor base for long-term maintenance
pick Smithereen if
- You want the Smithereen feature set and don't need the biggest community
- You prefer the Unlicense license terms
- Your stack matches Java
- You evaluated both and Smithereen fits your workflow better
About Mastodon
Mastodon is a free, open source, self hosted social network server built on ActivityPub that lets anyone run a microblogging community which interoperates with the wider Fediverse, and it is aimed at individuals, communities, and organisations that want to own their social graph instead of renting it from a platform.
read the full Mastodon overview →
About Smithereen
Smithereen is a federated, ActivityPub compatible social network server written in Java that gives a self hosted instance friends, walls, and groups, and it is aimed at administrators who want to run their own social space that talks to the wider fediverse rather than renting one from a platform.
read the full Smithereen overview →
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Frequently asked questions
Is Mastodon or Smithereen more popular?
Mastodon has 50,299 GitHub stars and Smithereen has 546. Mastodon has the larger community by that measure.
Are Mastodon and Smithereen free?
Both are open source. Mastodon is licensed under AGPL-3.0 and Smithereen under Unlicense. Neither carries a licence fee.
What is the difference between Mastodon and Smithereen?
Mastodon is written in Ruby and Smithereen in Java. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Mastodon or Smithereen?
Choose Mastodon if you want the larger community (50,299 stars) or its AGPL-3.0 licence terms. Choose Smithereen if its feature set, stack or Unlicense licence fits better. Both are self-hostable.