Mutatest

Windows · Mac · Linux

Freedom report

Three barsScore 6.5

Free tierA free tier is on its own pricing page
Open codeNo open-source code on record
Runs widely3 of 6 device platforms
DocumentedPlans, terms and facts published

Mutatest is ranked #3 of 25 in mutation testing tools on Freedom251. It runs on Linux, macOS, Windows. There is a free plan.

Mutatest plans and pricing

All plans

Mutatest Free Free and open source under the MIT License mutatest.readthedocs.io · 2 Oct 2026

Compared on mutation testing tools

Free plan: Yes
Supported languages: Python
Test frameworks: pytest
Parallel execution: Yes
Surviving mutant reports: Yes
Mutation quality gate: Yes
Mutation operators: AugAssign; BinOp; bitwise comparison; bitwise shift; BoolOp; Compare; Compare In; Compare Is; If; Index; NameConstant; Slice

Best Mutatest alternatives

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Two bars ArcMutate Free tier No. 1$8/mo6.6 One bar Mutant Free tier No. 2$20.83/mo6.5 One bar Stryker Mutator Free tier No. 4Free6.3 One bar Infection Paid plans No. 5—5.6 One bar muttest Paid plans No. 6—5.6 One bar PIT Paid plans No. 7—5.6

The record

Purpose: Mutatest is a diagnostic command-line tool for assessing test coverage by checking whether tests detect small code mutations.
Mutation method: It uses Python’s Abstract Syntax Tree grammar to produce valid mutants and changes local __pycache__ files instead of source files.
Coverage: When coverage data is available, mutation targets can be restricted to lines marked as covered.
Sampling: It randomly samples mutation locations and potential mutations, and a random seed can make trials reproducible.
Controls: The command line supports run modes, mutation category selection, file exclusions, timeouts, output reports, and survivor thresholds.
API: Mutatest includes an API for custom mutation controls.
Integrations: The documentation describes running test commands such as pytest and using coverage data to filter mutation targets.
CI use: Mutatest can raise an exception when surviving mutants meet a configured threshold, for use in automated runs such as a continuous integration stage.
Platform support: The project says it was tested on Linux, Windows, and MacOS with Azure pipelines.
Python support: The installation documentation requires Python 3.7 or Python 3.8.
Known limitation: The documentation warns that repeated test-suite runs can make mutation testing slow, so it is intended as a diagnostic tool rather than a run over an entire codebase on every commit.
Test runner limitation: Although a test command can be supplied, the documentation says only pytest has been tested to date.
Support: The project directs users to its GitHub issue tracker to submit bugs or request features.
Price from: Free

Where it ranks on Freedom251

Best Mutation Testing Tools in 2026#3 of 25

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Sources

mutatest.readthedocs.io/en/latest/· checked 2 Oct 2026
mutatest.readthedocs.io/en/latest/install.html· checked 2 Oct 2026
mutatest.readthedocs.io/en/latest/commandline.html· checked 2 Oct 2026
github.com/EvanKepner/mutatest· checked 2 Oct 2026
mutatest.readthedocs.io/en/latest/license.html· checked 2 Oct 2026