Karma
A test runner that runs JavaScript tests in real browsers. Now deprecated by its maintainers.
- Stars
- 12k
- Forks
- 1.7k
- Licence
- MIT
- Language
- JavaScript
- Last update
- 5 months ago
- Type
- Dev tool
What it is
Karma is a tool that runs JavaScript test code inside real web browsers, so you can check your code behaves correctly where it will actually run. It starts a local HTTP server and generates the test runner page, and you can use it with testing frameworks like Jasmine, Mocha, or QUnit. The README states that Karma is now deprecated and no longer accepting new features or general bug fixes, so new projects should evaluate the alternatives it lists.
- Run the same unit test suite in several real browsers on your own machine
- Run tests automatically on every file save during development
- Run browser tests on a continuous integration server
- Generate coverage reports with Istanbul
Great for
- Teams with existing Karma test suites that need to keep them running for now
- Developers who want tests run in several real browsers, including desktop and mobile
- Projects that already use Istanbul coverage or RequireJS with Karma
- Angular projects that have not yet migrated off Karma
Not ideal for
- New projects, because the README says Karma is deprecated and not accepting new features or general bug fixes; alternatives such as Web Test Runner, jasmine-browser-runner, Jest, or Vitest are named in the README
- Anyone who needs a testing framework or assertion library by itself, because Karma is only the runner and needs a framework adapter
- Teams wanting ongoing feature development, since the README says only critical security issues will still be fixed
How to get it
- 1
Install with a package manager
You'll need: Node.js
Clone the repository
git clone https://github.com/karma-runner/karma - 2
Run it
- Read the installation guide linked in the README at karma-runner.github.io
- Install a testing framework adapter such as karma-jasmine or karma-mocha
- Follow the configuration guide to set up your browsers and test files
- Run your tests through Karma from your terminal
- 3
Get the most out of it
- Use framework adapters like Jasmine, Mocha, or QUnit, since Karma itself does not include a test framework
- Add Istanbul to generate coverage reports
- Use RequireJS if your source files are organized that way
- Check the browsers page to see which browsers are supported
Downloads
Strengths
- Runs tests in real browsers rather than only in a simulated environment
- Works with popular frameworks such as Jasmine, Mocha, and QUnit through adapters
- Has been used widely, with about 11,950 GitHub stars and an MIT license
Trade-offs
- Officially deprecated; only critical security issues will be fixed for a limited period
- The README does not describe newer features, so it may not fit modern testing workflows
How it compares
| Project | Stars | Type | Level | Updated | Best for |
|---|---|---|---|---|---|
| karma (this) | 12k | Dev tool | intermediate | 5 months ago | Teams with existing Karma test suites that need to keep them running for now |
| jest | 45.5k | Library | beginner | 4 days ago | JavaScript or TypeScript developers who want a testing setup that works with little configuration |
| vitest | 17.3k | Library | intermediate | 4 days ago | JavaScript or TypeScript developers already using Vite |
Stats synced from GitHub. The assessment above was drafted with AI from the project's README on 2026-10-29 and may miss recent changes — check the README before relying on a command. MIT licence: free to use, modify and distribute, including commercially, as long as you keep the copyright notice.