fastify vs koa
fastify and koa have comparable adoption (31,079,568 vs 30,749,504 downloads per month). koa ships 52% less gzipped JavaScript (61.8 kB vs 129.8 kB), which matters if bundle size is a priority. Both projects are actively maintained.
| Metric | fastify | koa |
|---|---|---|
| Weekly downloads | 7,307,661 | 7,366,089✓ |
| Monthly downloads | 31,079,568✓ | 30,749,504 |
| GitHub stars | 36,351✓ | 35,709 |
| Minified size | 471.7 kB | 358.3 kB✓ |
| Minified + gzipped | 129.8 kB | 61.8 kB✓ |
| Dependencies | 15✓ | 18 |
| Open issues | 146 | 32✓ |
| Last commit | 2026-06-01✓ | 2026-05-28 |
| Latest version | 5.8.5 | 3.2.1 |
| License | MIT | MIT |
When to choose which
fastify
A fast, low-overhead framework with schema validation.
Choose it when: High-throughput APIs where you want JSON-schema validation, structured logging and first-class TypeScript.
- + Very high performance
- + Schema validation built-in
- + Great TypeScript
- - Smaller ecosystem than Express
- - Plugin model to learn
koa
A lightweight, modern core by the Express team.
Choose it when: You want a tiny async/await middleware core and to assemble the rest yourself.
- + Modern async middleware
- + Tiny core
- + Clean design
- - Assemble everything yourself
- - Smaller ecosystem
Feature comparison
| Feature | fastify | koa |
|---|---|---|
| Philosophy | Minimal+ | Minimal |
| TypeScript-first | ✓ Yes | Partial |
| Performance | Very high | High |
| Built-in features | Validation, logging | Minimal |
| Ecosystem | Large | Medium |
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[](https://devcompare.dev/compare/fastify-vs-koa)Data from npm, Bundlephobia and GitHub. Last updated 2026-06-02.