head to head · open source
effect vs aya
effect has 16,138 GitHub stars, 752 forks, 253 open issues and last shipped today. aya has 4,817 stars, 476 forks, 201 open issues and last shipped today. effect leads on adoption by 235% (16,138 vs 4,817 stars). effect is written in TypeScript under MIT; aya is written in Rust under Apache-2.0. effect has attracted 5% as many forks as stars, aya 10%. aya was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (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 | aya | |
|---|---|---|
| GitHub stars | ★ 16K | ★ 4.8K |
| License | MIT | Apache-2.0 |
| Written in | TypeScript | Rust |
| Last push | 2026-09-20 | 2026-09-20 |
| Forks | ⑂ 752 | ⑂ 476 |
| 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 aya if
- You want the aya feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Rust
- You evaluated both and aya 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 aya
Aya is an eBPF library for the Rust programming language, built with a focus on developer experience and operability, and it exists so that Rust developers can load, attach, and drive eBPF programs running inside the Linux kernel without depending on C toolchains or C eBPF frameworks.
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Frequently asked questions
Is effect or aya more popular?
effect has 16,138 GitHub stars and aya has 4,817. effect has the larger community by that measure.
Are effect and aya free?
Both are open source. effect is licensed under MIT and aya under Apache-2.0. Neither carries a licence fee.
What is the difference between effect and aya?
effect is written in TypeScript and aya in Rust. 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 aya?
Choose effect if you want the larger community (16,138 stars) or its MIT licence terms. Choose aya if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.