Zephyr vs FreeRTOS vs RIOT
A side-by-side look at how actively Zephyr, FreeRTOS and RIOT are developed on GitHub — popularity, contributor base, commit activity and how quickly issues and pull requests move.
What the numbers say
- Zephyr is the most-starred of the 3, with 17k stars — about 3.7× FreeRTOS's 4.5k.
- Over the 52 weeks to the snapshot, Zephyr recorded the most commits (29k), against 69 for FreeRTOS.
- Zephyr has closed or merged the most pull requests in its lifetime: 86k.
- Relative to its popularity, FreeRTOS carries the lightest open-issue load: 9.5 open issues per 1,000 stars, versus 120.2 for Zephyr.
- FreeRTOS had gone 34 days without a push at the time of the snapshot.
Head-to-head
Snapshot taken 30 September 2026.
| Metric | Zephyr Slowing | FreeRTOS Slowing | RIOT Active |
|---|---|---|---|
| Stars | 17k | 4.5k | 5.8k |
| Forks | 10k | 1.6k | 2.1k |
| Contributors | 4.7k | 245 | 557 |
| Commits, last 52 weeks | 29k | 69 | 2.0k |
| Open issues | 2.0k | 43 | 414 |
| Open pull requests | 1.9k | 54 | 490 |
| Closed / merged PRs | 86k | 1.1k | 19k |
| Watchers | 414 | 113 | 245 |
| Last push | 30 Sep 2026 | 26 Aug 2026 | 30 Sep 2026 |
| Latest release | v4.4.2 (Aug 2026) | V11.3.1 (Aug 2026) | 2026.07 (Aug 2026) |
| Main language | C | C | C |
| Licence | Apache-2.0 | MIT | LGPL-2.1 |
| Created | May 2016 | Sep 2019 | Dec 2012 |
Bold marks the highest value in a row. “Active / Slowing / Dormant” is a simple heuristic from how recently code was pushed and open issues per star — a starting point, not a verdict. Stars measure popularity, not quality.
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