Jumble
Mutation testing tool for JUnit test suites
Nester
Mutation testing tool for C# NUnit tests
Stryker Mutator
Mutation testing for JavaScript, C# and Scala
PIT (Pitest)
Mutation testing system for Java and the JVM
Arcmutate
Enterprise mutation testing for Java and Kotlin, built on PIT
mutmut
Mutation testing system for Python