Mutode
Mutode is free, open-source mutation testing software for JavaScript and Node.js projects.
What Mutode is
Mutode is free, open-source mutation testing software for JavaScript and Node.js projects. It creates small code variations called mutants, runs the project’s tests, and shows whether those tests detect each change. A failing test kills a mutant; a passing test leaves it survived. Mutode reports killed, survived, and discarded mutants, calculates mutant coverage, and provides surviving-mutant reports. Its documented operators can change boolean, numeric, and string literals, modify conditionals and operators, or remove array elements, function arguments, object properties, lines, and switch cases. Before proceeding, Mutode runs the project’s npm test command and reports an error if the clean suite exits unsuccessfully. Users can select operators and configure concurrent runners; the documented default is four. Parallel runs use project copies, and logs are saved in a .mutode folder. It requires Node 8 or later and supports global or local npm installation, npx, and package.json scripts.
Good
- Free and open source
- Reports killed, survived, and discarded mutants
- Calculates mutant coverage
- Supports configurable mutation operators
- Offers concurrent runners with a default of four
Watch out
- Requires Node 8 or later
- Runs the project’s npm test command first
- Documentation lists no third-party integrations
- Supports JavaScript projects
Who it suits
Mutode suits JavaScript and Node.js developers who want mutation testing within npm projects. It fits teams reviewing test detection through configurable operators and concurrent runners.
Verdict
Mutode provides a focused mutation-testing workflow with configurable operators, coverage reporting, and parallel runners. Its npm-centered setup and Node requirement define where it fits best.
The facts
Each one read from Mutode's own pages, with the date it was checked.
What it does
- Concurrency
- The concurrency option controls mutant runners and defaults to 4.checked 9 Oct 2026
- Configuration
- Users can select mutation operators and set concurrency; the command-line documentation gives a default concurrency of 4.checked 4 Oct 2026
- How it works
- It makes small code changes called mutants and runs the test suite; failing tests kill a mutant, while passing tests mean it survived.checked 9 Oct 2026
- Install
- The page documents global npm installation, local development dependency installation, npx usage, and package.json scripts.checked 4 Oct 2026
- Installation
- The page documents installing Mutode globally with npm or locally as a development dependency.checked 9 Oct 2026
- Integrations
- The documentation describes npm installation and execution but does not list third-party service integrations.checked 4 Oct 2026
- Intended users
- Mutode is a mutation testing tool for JavaScript and Node.js projects.checked 4 Oct 2026
- License
- The page identifies the license as MIT and names Diego Rodríguez Baquero in its copyright notice.checked 9 Oct 2026
- Logs
- Mutode saves logs in a .mutode folder in the project.checked 4 Oct 2026
- Mutation operators
- Documented operators include changing literals and conditionals, altering math operators, and removing code elements such as array elements, function arguments, lines, and switch cases.checked 9 Oct 2026
- Operator selection
- Users can select mutation operators with the --mutators option.checked 9 Oct 2026
- Parallel execution
- Mutode creates project copies for concurrent mutant runners and supports configuring the number of runners.checked 4 Oct 2026
- Purpose
- Mutode performs mutation testing for Node.js and JavaScript.checked 9 Oct 2026
- Results
- Mutode reports killed, survived, and discarded mutants and calculates mutant coverage.checked 4 Oct 2026
- Runtime requirement
- Mutode requires Node 8 or later.checked 9 Oct 2026
- Security and compliance
- The opened product pages do not state security certifications or compliance claims.checked 4 Oct 2026
- Test requirement
- Mutode runs the project’s npm test command before proceeding and reports an error if the clean test suite exits with a nonzero code.checked 4 Oct 2026
- Ways to run
- The page documents running Mutode directly, with npx, or through a package.json script.checked 9 Oct 2026
- What it does
- Mutode generates small code changes called mutants and runs tests to reveal whether the tests detect them.checked 4 Oct 2026
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