SoapUI is a free and open source cross-platform functional testing
The OWASP ZAP core project
Flexible, lightweight multi-language test reporting tool
Load testing tool for analyzing and measuring performance of services
Programmer-friendly testing framework for Java and the JVM
Test automation made simple
Most popular Mocking framework for unit tests written in Java
HTTP load testing tool and library. It's over 9000!
Gateway service providing dynamic routing, monitoring and more
Coverage-guided, in-process fuzzing for the JVM
API automation and load testing framework
Lightweight service virtualization/ API simulation / API mocking tool
State of the art mutation testing system for the JVM
Python version of the Playwright testing and automation library
Powerful, elegant and flexible test framework for Kotlin
.NET version of the Playwright testing and automation library
Modern concurrency tools including agents, futures, promises, etc.
Testing Kotlin and Java annotation processors, compiler plugins
The Open Source Test Automation Platform
Android unit testing framework
Optimizer for mobile applications
Cucumber for Ruby
Benchmarking tool
Database Subsetter and Relational Data Browser
Java GUI-Less browser, supporting JavaScript, to run against web pages