head to head · open source
Mastodon vs lemmy-ui
Mastodon has 50,299 GitHub stars, 7,498 forks, 4,525 open issues and last shipped yesterday. lemmy-ui has 1,008 stars, 379 forks, 55 open issues and last shipped 4 days ago. Mastodon leads on adoption by 4,890% (50,299 vs 1,008 stars). Mastodon is written in Ruby under AGPL-3.0; lemmy-ui is written in CSS under AGPL-3.0. Mastodon has attracted 15% as many forks as stars, lemmy-ui 38%. Mastodon was the more recently maintained of the two, and both are self-hostable with no licence fee.
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 | lemmy-ui | |
|---|---|---|
| GitHub stars | ★ 50K | ★ 1.0K |
| License | AGPL-3.0 | AGPL-3.0 |
| Written in | Ruby | CSS |
| Last push | 2026-09-17 | 2026-09-14 |
| Forks | ⑂ 7.5K | ⑂ 379 |
| 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 lemmy-ui if
- You want the lemmy-ui feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches CSS
- You evaluated both and lemmy-ui 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 lemmy-ui
lemmy ui is the official web app for Lemmy — the federated link aggregator and forum of the Fediverse — and it is built for the people who run and use Lemmy servers rather than for anyone seeking a centrally hosted social network.
read the full lemmy-ui overview →
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Frequently asked questions
Is Mastodon or lemmy-ui more popular?
Mastodon has 50,299 GitHub stars and lemmy-ui has 1,008. Mastodon has the larger community by that measure.
Are Mastodon and lemmy-ui free?
Both are open source. Mastodon is licensed under AGPL-3.0 and lemmy-ui under AGPL-3.0. Neither carries a licence fee.
What is the difference between Mastodon and lemmy-ui?
Mastodon is written in Ruby and lemmy-ui in CSS. 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 lemmy-ui?
Choose Mastodon if you want the larger community (50,299 stars) or its AGPL-3.0 licence terms. Choose lemmy-ui if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.