Professional software tool for HTTP testing and debugging

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

Design, debug, and test APIs locally or in the cloud

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.

Hoppscotch is an open-source API development ecosystem that helps you create and test your API requests saving precious time in development.

Unifying API testing, API Performance testing, API Mocks and UI testing.