Infection vs pytest-gremlins

Infection7.4Visit PGpytest-gremlins6.6Visit

Higher score Infection #4 in Mutation Testing Tools 7.4/10 Free plan Free plan✓ 4 of 4 features Visit Infection

vs

PG pytest-gremlins #9 in Mutation Testing Tools 6.6/10 Open source ✓ 4 of 4 features Try pytest-gremlins

• Infection fits best

  PHP teams with CI quality gates

• pytest-gremlins fits best

  pytest teams prioritizing fast CI feedback

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Side by side

Feature	Infection 7.4/10 Visit ↗	PGpytest-gremlins 6.6/10 Visit ↗
At a glance
Editor score	7.4	6.6
Ranking	#4 in Mutation Testing Tools	#9 in Mutation Testing Tools
Best for	PHP teams with CI quality gates	pytest teams prioritizing fast CI feedback
Pricing model	Free	Free
Starting price	Not published	Not published
Free plan	✓ (best)	Not published
Free trial	—	—
Support	Community, Docs	Docs, Community
Integrations	6 integrations	4 integrations
Built for	Solo, Small business, Mid-market, Enterprise	Solo, Small business, Mid-market, Enterprise
Features Infection 4/4 · pytest-gremlins 4/4
Incremental analysis	✓	✓
Parallel execution	✓	✓
Surviving mutant reports	✓	✓
Mutation quality gate	✓	✓
Specs
Supported languages	PHP	Python
Test frameworks	PHPUnit, PhpSpec, Codeception, Testo	pytest
Mutation operators	Arithmetic, boolean, cast, conditional boundary, conditional negotiation, equality, function signature, nullify, number, operator, regex, removal, return value, visibility, and unwrap mutators	comparison, boundary, boolean, arithmetic, return
Our review
Pros	Broad PHP mutators with configurable profiles and custom mutators Parallel execution, coverage reuse, and changed-line filtering CI thresholds with HTML, text, JSON, GitHub, and GitLab reports	Native pytest integration with coverage-guided test selection Incremental caching and parallel execution support faster feedback HTML, JSON, and survivor reports support CI quality gates
Cons	Supports PHP rather than multiple programming languages No AI features are included Mutation analysis is centered on supported PHP test frameworks	Requires Python 3.11 or newer Supports Python and pytest rather than multiple language ecosystems Mutation results depend on the configured operator set and test suite
Our verdict	Infection is an open-source mutation testing framework for PHP teams that want to measure whether their tests detect code changes. It uses AST-based source-code mutation, runs relevant test cases, and reports killed, escaped, errored, and… Read the review →	pytest-gremlins is an open-source pytest plugin for mutation testing in Python projects. It injects configurable mutations into code, runs relevant tests, and reports which changes tests detect or miss. Developers and teams seeking… Read the review →

Strengths and trade-offs

• Infection — where it wins

  • Broad PHP mutators with configurable profiles and custom mutators
  • Parallel execution, coverage reuse, and changed-line filtering
  • CI thresholds with HTML, text, JSON, GitHub, and GitLab reports

  Where it doesn't

  • Supports PHP rather than multiple programming languages
  • No AI features are included
  • Mutation analysis is centered on supported PHP test frameworks

• pytest-gremlins — where it wins

  • Native pytest integration with coverage-guided test selection
  • Incremental caching and parallel execution support faster feedback
  • HTML, JSON, and survivor reports support CI quality gates

  Where it doesn't

  • Requires Python 3.11 or newer
  • Supports Python and pytest rather than multiple language ecosystems
  • Mutation results depend on the configured operator set and test suite

• Infection7.4/10 · Free plan

  A free, open-source PHP mutation testing framework with CI quality gates.

  Visit InfectionFull verdict →
• PGpytest-gremlins6.6/10 · Open source

  A focused, open-source mutation testing plugin for Python teams using pytest.

  Try pytest-gremlinsFull verdict →