Tech riderRev. 1 Oct 2026

Mutant

Ch 037.1of 25 Mutation Testing Tools

1Runs onLinux, Mac
2CostsFree plan · paid from $20.83/mo
3Supported languagesRuby
4Test frameworksRSpec, Minitest, Test::Unit
5Incremental analysisYes
6Parallel executionYes
7Surviving mutant reportsYes
8Mutation operatorsArithmetic, logical, bitwise, statement removal, return-value modification, ordering

8 lines stated Written from the maker's own pages: github.com

Visit site Alternatives

Overview

Mutant is ranked #3 of 25 in mutation testing tools on Specifiction. It runs on Linux, macOS. There is a free plan. Paid plans start at $20.83/mo.

Mutant plans and pricing

All plans

Open source Free public repositories · full feature set github.com · 1 Oct 2026

Commercial monthly $30/mo per developer any number of repositories · CI use requires no additional subscriptions github.com · 1 Oct 2026

Commercial yearly $250/yr per developer any number of repositories · CI use requires no additional subscriptions github.com · 1 Oct 2026

Enterprise Not published volume subscriptions · custom plans github.com · 1 Oct 2026

Compared on mutation testing tools

Free plan: Yesgithub.com
Paid from: $30/mogithub.com
Supported languages: Rubygithub.com
Test frameworks: RSpec, Minitest, Test::Unitgithub.com
Incremental analysis: Yesgithub.com
Parallel execution: Yesgithub.com
Surviving mutant reports: Yesgithub.com
Mutation operators: Arithmetic, logical, bitwise, statement removal, return-value modification, orderinggithub.com

Facts

Purpose: Mutant is mutation testing for Ruby that systematically modifies code and verifies that tests catch each change.github.com · 1 Oct 2026
Test integrations: Mutant integrates with RSpec, Minitest, and Test::Unit.github.com · 1 Oct 2026
CI workflow: Mutant supports incremental mode for running mutation testing in CI.github.com · 1 Oct 2026
Ruby support: Mutant supports Ruby versions 3.2, 3.3, 3.4, and 4.0 for runtime, syntax, and mutations.github.com · 1 Oct 2026
Rails integration: Mutant supports Rails applications with parallel-worker database isolation for PostgreSQL and SQLite.github.com · 1 Oct 2026
Rails versions: The Rails integration is verified for Rails 7.2, 8.0, and 8.1.github.com · 1 Oct 2026
Subject limitation: Mutant cannot emit mutations for methods defined within closures such as module_eval, class_eval, define_method, or define_singleton_method.github.com · 1 Oct 2026
Execution model: Mutant runs exclusively on developers’ machines or in CI.github.com · 1 Oct 2026
Source-code privacy: Schirp DSO LTD states that it does not get access to customers’ source code, customer data, or other sensitive material.github.com · 1 Oct 2026
Data sharing: Customer information is never shared or sold to anyone.github.com · 1 Oct 2026
Support channels: Mutant provides Discord, GitHub Issues, and release announcements as communication channels.github.com · 1 Oct 2026
Commercial licensing: Commercial subscriptions are required per developer using Mutant on commercial code, while CI execution requires no additional subscriptions.github.com · 1 Oct 2026
Creator: Mutant was created and is developed by Markus Schirp and is cited as subject of IEEE-published research.github.com · 1 Oct 2026