Requestly is an open-source tool that simplifies API development, testing, mocking, and integration for developers and QAs.

Percy is a visual testing and monitoring tool that focuses on detecting visual changes in web applications

Simulate APIs, integrations, and environments at enterprise scale.

Testing and validating REST services in Java is harder than in dynamic languages such as Ruby and Groovy. REST Assured brings the simplicity of using these languages into the Java domain.

Burp or Burp Suite is a set of tools used for penetration testing of web applications. It is developed by a company named Portswigger who make freely available a Web Security Academy which has a range of lessons on penetration testing.

HyperTest is a no-code test automation tool that regresses all your APIs by auto-generating integration tests using your network traffic, also giving a way to reproduce these failures inside actual user-journeys.