head to head · open source
effect vs aya
effect has 17,476 GitHub stars, 895 forks, 253 open issues and last shipped yesterday. aya has 4,892 stars, 484 forks, 201 open issues and last shipped 2 days ago. effect leads on adoption by 257% (17,476 vs 4,892 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%. effect 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 | ★ 17K | ★ 4.9K |
| License | MIT | Apache-2.0 |
| Written in | TypeScript | Rust |
| Last push | 2026-11-04 | 2026-11-03 |
| Forks | ⑂ 895 | ⑂ 484 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick effect if
- You weight community size — 17K 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 Effect is a library for building robust, maintainable, type safe, and production grade applications in TypeScript. It helps you handle the hard problems at scale: typed errors, dependency injection, structured concurrency, scheduling, tracing, and unified schema validation. Effect V4 is currently a release candidate. The main branch contains v4 development. Install V4 RC Requirements TypeScript 5.9 or newer. TypeScript 7 is recommended for the best performance and compatibility with Effect's TypeScript tooling. Node.js 18 or newer is the general minimum for running Effect on Node.js. Some integration…
read the full effect overview →
About aya
[![Crates.io][crates badge]][crates url] ![License][license badge] [![Build status][build badge]][build url] [![Book][book badge]][book url] [![Gurubase][gurubase badge]][gurubase url] [crates badge]: [crates url]: [license badge]: [build badge]: [build url]: [book badge]: [book url]: [gurubase badge]: [gurubase url]: API Documentation [![Unreleased Documentation][git docs badge]][git api docs] [![Documentation][api docs badge]][api docs] [git docs badge]: [git api docs]: [api docs badge]: [api docs]: Community [![Discord][discord badge]][chat url] [![Awesome][awesome badge]][awesome aya] Join [the conversation…
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Frequently asked questions
Is effect or aya more popular?
effect has 17,476 GitHub stars and aya has 4,892. 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 (17,476 stars) or its MIT licence terms. Choose aya if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.