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.

A modern, resource-friendly REST client for Windows 10

Playwright enables reliable end-to-end testing for modern web apps.

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.

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

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