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Pick up to four tools and compare adoption, momentum and maintenance at a glance. The crown marks the leader in each row.
| Metric | Joi | Zod | Pydantic | Ajv |
|---|---|---|---|---|
| Stars | 21.2k | 44.3k | 29.4k | 14.9k |
| Weekly downloads | 34M | 454M | 279M | 519M |
| Download growth | +17% | +47% | +35% | +17% |
| Popularity score | 86/100 | 93/100 | 92/100 | 89/100 |
| Forks | 1.5k | 2.3k | 3.2k | 1.1k |
| Open issues | 213 | 122 | 600 | 405 |
| Last commit | 1w ago | 5d ago | 3d ago | 2mo ago |
| Latest version | 18.3.2 | 4.6.7 | 2.14.3Nov 5, 2026 | 8.20.0 |
| License | n/a | MIT | MIT | MIT |
| First released | 2012 | 2020 | 2017 | 2015 |
| Signals | Legacy | Popular | Popular | Popular |
| Listed in | Backend › Validation & Schemas | Frontend › Forms & ValidationBackend › Validation & Schemas | Backend › Validation & Schemas | Backend › Validation & Schemas |
Hover for exact values; switch to log scale for tools of very different sizes. Not shown (no comparable download data): Pydantic.