Radar check
What we found when we opened it. Every bar is one fact, with its date.
Last code pushed 26 Oct 2026, the same day before this check.
Latest release v10.1.1 on 23 Oct 2026.
Public since February 2016, a little over 10 years.
3,277 stars and 304 forks.
73 commits and 47 new issues in the last 90 days.
164 contributors. 70 pull requests merged in 90 days.
No security policy file says how to report a problem. No published security advisories.
How the bars are scored
- Alive. Days since the last code push: a week or less 100, a month 90, three months 70, six months 50, a year 30, eighteen months 15, older 0.
- Releases. Age of the latest GitHub release, on a similar scale; no bar when the project publishes no releases.
- Maturity. Age of the project: eight years 100, five 90, three 70, two 55, one 40, six months 25, younger 10.
- Adoption. Stars on a log scale: 100,000 stars is 100, 10,000 is 80, 1,000 is 60, 100 is 40.
- Activity. Commits in the last 90 days: 300 or more 100, 100 85, 30 65, 10 45, any 25.
- Community. People who have contributed: 100 or more 100, 30 80, 10 60, 5 40, 2 25, one 10.
- Security. A published security policy 80, none 40; published advisories are listed, not scored.
Checked by Repo Radar on 26 Oct 2026 from the repository on GitHub.
In simple English
Normal tests check if your code runs. Mutation testing checks if your tests actually notice when code changes. It breaks your code on purpose in small ways to see if your test suite fails. If your tests still pass when code is broken, your tests are not doing their job. This tool costs time on your computer and requires an existing test suite.
What it is
StrykerJS (a command-line tool that alters your source code to test the quality of your test suite) injects small errors into your JavaScript or TypeScript code. It then runs your tests to see if they catch the introduced bugs.
What it is good for
Developers who want to find blind spots in their unit tests and make sure their test suite can actually catch regressions.
- Finds weak spots in existing unit tests.
- Supports major test frameworks like Jest, Mocha, and Jasmine.
- Integrates into continuous integration pipelines.
- Takes a long time to run on large codebases because it runs tests repeatedly.
- Requires a solid existing test suite to be useful.
- Setup and configuration can be complex for custom build setups.
manual code review for test quality
Jest
- stryker-mutator/stryker-js3.3k stars
The original Stryker mutation testing tool for the .NET ecosystem.
- evanw/esbuild40k stars
Joins many JavaScript, TypeScript and CSS files into one, in well under a second.
- Textualize/textual38k stars
Lets a Python program draw a real interface inside a terminal, and serve the same thing to a browser.
- python-attrs/cattrs1.1k stars
Turns loose data into declared Python objects, and declared objects back into loose data.
npm install --save-dev @stryker-mutator/core npx stryker init