head to head · open source
effect vs openwolf
effect has 16,138 GitHub stars, 752 forks, 253 open issues and last shipped today. openwolf has 2,351 stars, 212 forks, 56 open issues and last shipped 5 days ago. effect leads on adoption by 586% (16,138 vs 2,351 stars). effect is written in TypeScript under MIT; openwolf is written in TypeScript under AGPL-3.0. effect has attracted 5% as many forks as stars, openwolf 9%. effect was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (cli, observability), 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
| effect | openwolf | |
|---|---|---|
| GitHub stars | ★ 16K | ★ 2.4K |
| License | MIT | AGPL-3.0 |
| Written in | TypeScript | TypeScript |
| Last push | 2026-09-20 | 2026-09-15 |
| Forks | ⑂ 752 | ⑂ 212 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick effect if
- You weight community size — 16K stars and counting
- You want the MIT license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick openwolf if
- You want the openwolf feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches TypeScript
- You evaluated both and openwolf fits your workflow better
About effect
Effect is a TypeScript library for building robust, maintainable, type safe, and production grade applications. It lives in the TypeScript and JavaScript ecosystem, distributed as the core effect package alongside a monorepo of integration packages that extend it. The project is MIT licensed, has been developed for roughly seven years, and currently ships Effect V4 as a release candidate, with the main branch holding v4 development and the v3 branch retaining the previous line.
read the full effect overview →
About openwolf
OpenWolf is an open source TypeScript tool that keeps portable project memory for coding agents such as Claude Code, Codex and OpenCode and measures token usage from harness transcripts, aimed at developers who lose context between sessions or across agents.
read the full openwolf overview →
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Frequently asked questions
Is effect or openwolf more popular?
effect has 16,138 GitHub stars and openwolf has 2,351. effect has the larger community by that measure.
Are effect and openwolf free?
Both are open source. effect is licensed under MIT and openwolf under AGPL-3.0. Neither carries a licence fee.
What is the difference between effect and openwolf?
effect is written in TypeScript and openwolf in TypeScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, effect or openwolf?
Choose effect if you want the larger community (16,138 stars) or its MIT licence terms. Choose openwolf if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.