fast-check
Property-based testing framework for JavaScript to generate and test edge cases automatically.
Testing npm MIT
Used in agent projects
51
0.4% of 12,697 public repos built with AI coding agents
Rank in testing
#19 of 40
by use in those projects
Downloads
50.7M
npm, last 7 days, fast-check
GitHub stars
5,193
last push Oct 10, 2026
How fast-check is used
fast-check is a dependency in 51 of the 12,697 public GitHub projects set up for AI coding agents that we scanned (0.4%), #19 of 40 in testing. The most used alternative there is Vitest. Projects that use it most often also use Vitest (68.6%), Playwright (JavaScript) (47.1%), jsdom (35.3%). It is more common in projects set up for Kiro (4.1%) than for GitHub Copilot (0.6%).
Often used with fast-check
| Vitest | 68.6% of fast-check projects · 5.6× more than average |
|---|---|
| Playwright (JavaScript) | 47.1% of fast-check projects · 5.3× more than average |
| jsdom | 35.3% of fast-check projects · 6.6× more than average |
| TypeScript | 84.3% of fast-check projects · 1.5× more than average |
| Vite | 52.9% of fast-check projects · 2.3× more than average |
| Testing Library | 27.5% of fast-check projects · 3.8× more than average |
| Knip | 25.5% of fast-check projects · 21.6× more than average |
| Prettier | 41.2% of fast-check projects · 2.4× more than average |
By coding agent
| Claude Code | 1.0% of projects set up for it |
|---|---|
| GitHub Copilot | 0.6% of projects set up for it |
| Cursor | 0.6% of projects set up for it |
| OpenAI Codex | 2.4% of projects set up for it |
| Gemini CLI | 1.6% of projects set up for it |
| Kiro | 4.1% of projects set up for it |
Share of public repos configured for each agent that list fast-check as a dependency.
Install
| Package | npm install fast-check |
|---|---|
| Main stacks | TypeScript / JavaScript (40), Next.js (6), Python (2), PHP (1) |
| Example projects | nirholas/three.ws, OriginTrail/dkg, Real1tyy/Nexus-Properties, proompteng/bilig, 3fn/DesignerPunk |
Alternatives to fast-check
| Tool | Used in agent projects | Downloads / wk | GitHub stars | License |
|---|---|---|---|---|
| Vitest npm Next-generation testing framework powered by Vite with native ESM. |
1,549 (12.2%) | 123M | 17.2K | MIT |
| Playwright (JavaScript) npm Cross-browser automation library for end-to-end testing. |
1,117 (8.8%) | 74.2M | 97.4K | Apache-2.0 |
| Testing Library npm Testing utilities for React encouraging testing user behavior. |
915 (7.2%) | 68.7M | 19.7K | MIT |
| Jest npm Delightful JavaScript testing framework with minimal configuration. |
702 (5.5%) | 46.3M | 45.6K | MIT |
| jsdom npm JavaScript implementation of web standards for testing DOM interactions. |
681 (5.4%) | 112M | 21.7K | MIT |
| pytest pypi Simple, powerful Python testing framework with fixtures and plugins. |
330 (2.6%) | 196M | 14.6K | — |
| Chai npm BDD/TDD assertion library for Node.js and browsers with expressive syntax. |
305 (2.4%) | 14M | 8,265 | MIT |
| Mocha npm Feature-rich JavaScript test framework for Node.js and browsers. |
281 (2.2%) | 12.6M | 22.9K | MIT |