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.

API Testing Platform that automatically generates unit test cases with dependency mocks from API calls

Selenium automates browsers. That's it! What you do with that power is entirely up to you.

Automate API workflows. Chain HTTP requests. Validate. Zero code.

Postman is an API platform for building and using APIs. Postman simplifies each step of the API lifecycle and streamlines collaboration so you can create better APIs—faster.

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.