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Tech riderRev. 30 Sept 2026

fast-check

Ch 036.8of 27 Property-Based Testing Tools
  1. 1Runs onAPI, Linux, Web
  2. 2CostsFree plan
  3. 3Supported languagesJavaScript, TypeScript
  4. 4Test runner supportJest, Mocha, Vitest, Ava, Bun, Deno, Node.js test runner
  5. 5Failing-case shrinkingYes
  6. 6Stateful testingYes
  7. 7Reproducible failuresYes
7 lines stated Written from the maker's own pages: fast-check.dev, github.com
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Overview

fast-check is ranked #3 of 27 in property-based testing tools on Specifiction. It runs on API, Linux, Web. There is a free plan.

fast-check plans and pricing

All plans
fast-check Free MIT-licensed JavaScript/TypeScript testing library github.com · 30 Sept 2026

Compared on property-based testing tools

Free plan
Yesfast-check.dev
Supported languages
JavaScript, TypeScriptfast-check.dev
Test runner support
Jest, Mocha, Vitest, Ava, Bun, Deno, Node.js test runnerfast-check.dev
Failing-case shrinking
Yesfast-check.dev
Stateful testing
Yesfast-check.dev
Reproducible failures
Yesfast-check.dev

Facts

Purpose
fast-check is a property-based testing library for JavaScript and TypeScript that generates inputs, runs assertions over many cases, and shrinks failures to smaller counterexamples.fast-check.dev · 30 Sept 2026
Testing workflow
The library is test-runner agnostic and works with Jest, Mocha, Vitest, and other test runners.fast-check.dev · 30 Sept 2026
Test building blocks
Tests use arbitraries to generate values, properties to specify expected behavior, runners to execute properties, and plugins to extend runners.fast-check.dev · 30 Sept 2026
Configuration
Users can configure runs, seeds, generated value sizes, time limits, and result reporting globally or per assertion.fast-check.dev · 30 Sept 2026
Failure diagnosis
When a property fails, fast-check shrinks the input to a smaller counterexample and reports information that helps diagnose the failure.github.com · 30 Sept 2026
Additional testing
The project describes fuzzing and generative testing for finding issues including race conditions and prototype poisoning.fast-check.dev · 30 Sept 2026
Integrations
The ecosystem lists official integrations for AVA, Jest, and Vitest, along with connectors for libraries such as Zod and io-ts.fast-check.dev · 30 Sept 2026
Security testing
The ecosystem documents an official @fast-check/poisoning package for checking whether specially crafted inputs cause global prototype modifications.fast-check.dev · 30 Sept 2026
Runtime requirements
The repository lists fast-check 5.x as requiring Node.js 22.12.0 or later, ECMAScript 2025, and optionally TypeScript 5.8 or later.github.com · 30 Sept 2026
Open source
The GitHub repository identifies fast-check as a public project released under the MIT license.github.com · 30 Sept 2026
Support
The project invites code and non-code contributions, community help, and financial support through GitHub Sponsors or OpenCollective.fast-check.dev · 30 Sept 2026
Ecosystem limitations
The ecosystem page says it can provide stability and maintenance details for official packages, but no specific guarantees for non-official packages.fast-check.dev · 30 Sept 2026

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