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.

Hand-crafted lightweight Rest Client for testing APIs. Supports collections, environments, git collaboration and local storage.

The world’s first API testing platform that auto-generates unit test cases with dependency mocks from API calls. Using advanced AI, it simplifies test creation, debugging, and evolution, ensuring comprehensive coverage and boosting software quality.

Voiden is a developer-first API client with local storage, Git-integrated, all based on markdown + offline support.

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

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.