head to head · open source
ActivityWatch vs Kimai
ActivityWatch has 18,919 GitHub stars, 1,012 forks, 186 open issues and last shipped yesterday. Kimai has 5,005 stars, 844 forks, 350 open issues and last shipped yesterday. ActivityWatch leads on adoption by 278% (18,919 vs 5,005 stars). ActivityWatch is written in Python under MPL-2.0; Kimai is written in PHP under AGPL-3.0. ActivityWatch has attracted 5% as many forks as stars, Kimai 17%. ActivityWatch was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (time-tracker, time-tracking, timetracker), 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
| ActivityWatch | Kimai | |
|---|---|---|
| GitHub stars | ★ 19K | ★ 5.0K |
| License | MPL-2.0 | AGPL-3.0 |
| Written in | Python | PHP |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 1.0K | ⑂ 844 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick ActivityWatch if
- You weight community size — 19K stars and counting
- You want the MPL-2.0 license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick Kimai if
- You want the Kimai feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches PHP
- You evaluated both and Kimai fits your workflow better
About ActivityWatch
ActivityWatch is the free and open source automated time tracker in the productivity and time tracking ecosystem. It is written in Python and uses the MPL 2.0 license. The project records what a user does so the user can know how time has been spent, while keeping the data under the user's control.
read the full ActivityWatch overview →
About Kimai
Kimai is a free and open source, web based time tracking application written in PHP on the Symfony framework, licensed under AGPL 3.0. It is built as a multi user, multi timezone and multi language system that handles the time tracking use cases of freelancers as well as companies with dozens or hundreds of users. The project lives in the PHP ecosystem, stores its data in MariaDB or MySQL through Doctrine, and renders its interface with Tabler. It is distributed both as a self hosted on premise application and as a hosted SaaS version at kimai.cloud.
read the full Kimai overview →
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Frequently asked questions
Is ActivityWatch or Kimai more popular?
ActivityWatch has 18,919 GitHub stars and Kimai has 5,005. ActivityWatch has the larger community by that measure.
Are ActivityWatch and Kimai free?
Both are open source. ActivityWatch is licensed under MPL-2.0 and Kimai under AGPL-3.0. Neither carries a licence fee.
What is the difference between ActivityWatch and Kimai?
ActivityWatch is written in Python and Kimai in PHP. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, ActivityWatch or Kimai?
Choose ActivityWatch if you want the larger community (18,919 stars) or its MPL-2.0 licence terms. Choose Kimai if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.