Mocha
Mocha is a free, open-source JavaScript test framework that runs in Node.js and browsers.
What Mocha is
Mocha is a free, open-source JavaScript test framework that runs in Node.js and browsers. Tests run serially by default, and uncaught exceptions are associated with their test cases. For asynchronous tests, developers can use callbacks or return promises. Mocha also supports parallel execution in Node.js, though not in browsers. The command-line interface uses BDD as its default interface and offers a --ui option to select another interface. Reporter choices are configurable: the CLI defaults to spec, while browser runs default to HTML. Installation as a development dependency is documented for npm, pnpm, and yarn. Mocha 12 requires Node.js ^20.19.0 or >=22.12.0. Browser builds document support for evergreen Chrome, Edge, Firefox, and Safari. The project supports JavaScript and TypeScript and parameterized test cases, but has no built-in mocks. Its documentation lists editor-related packages for TextMate, JetBrains IDEs, Wallaby.js, Emacs, and VS Code. The project points users to its Discord and documentation explainers for additional information.
Good
- Free and open source.
- Supports callbacks and promises for asynchronous tests.
- Can run tests in parallel in Node.js.
- Configurable interfaces and reporters.
- Supports JavaScript, TypeScript, and parameterized cases.
Watch out
- Parallel mode is unavailable in browsers.
- Mocha 12 requires specific Node.js versions.
- No built-in mocks.
Who it suits
Mocha suits JavaScript and TypeScript developers who need a test framework for Node.js, browsers, or both. It is especially relevant when tests need asynchronous support or Node.js parallel execution.
Verdict
Mocha provides a flexible testing framework across Node.js and browser environments, with configurable interfaces and reporters. Check the Node.js requirement and browser parallel-mode limitation against your setup.
Plans and prices
From Mocha's own pricing page, checked 2 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Mocha | Free | Open-source JavaScript test framework · install as a development dependency |
The facts
Each one read from Mocha's own pages, with the date it was checked.
What it does
- Async testing
- Mocha supports asynchronous tests using callbacks or returned promises.checked 2 Oct 2026
- Editor integrations
- The docs list editor-related packages for TextMate, JetBrains IDEs, Wallaby.js, Emacs, and VS Code.checked 2 Oct 2026
- Install options
- The getting-started guide shows installation as a development dependency using npm, pnpm, or yarn.checked 2 Oct 2026
- Interfaces
- Mocha’s CLI lists BDD as the default interface and provides a --ui option for selecting an interface.checked 2 Oct 2026
- Maintainers
- The Mocha 12 release post says the release is ready for production use.checked 2 Oct 2026
- Parallel mode
- Mocha can run tests in parallel in Node.js, but parallel mode is not supported in browsers.checked 2 Oct 2026
- Purpose
- Mocha is a JavaScript test framework that runs on Node.js and in browsers.checked 2 Oct 2026
- Reporters
- Mocha supports configurable reporters, with the spec reporter as the CLI default and HTML as the browser default.checked 2 Oct 2026
- Runtime requirement
- Mocha 12 requires Node.js ^20.19.0 or >=22.12.0.checked 2 Oct 2026
- Security guidance
- Mocha says it runs in development, executes developer-provided code, and typically does not process untrusted input or access external networks.checked 2 Oct 2026
- Support
- The project points users to its Discord and documentation explainers for additional information.checked 2 Oct 2026
- Test execution
- Mocha runs tests serially by default and maps uncaught exceptions to their test cases.checked 2 Oct 2026
Where it runs
- Browser support
- Mocha provides browser builds and documents support for evergreen browser versions including Chrome, Edge, Firefox, and Safari.checked 2 Oct 2026
The company
- Founded
- 2011checked 28 Sep 2026
