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.

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

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

The Complete Continuous Testing Platform Any test. Any device. App quality without limits.

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.