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

The worlds most widely used web app scanner.

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

Real API Design-first Development Platform Design. Debug. Test. Document. Mock. Build APIs Faster & Together.

Achieve effortless quality with zero coding, zero maintenance, and the autonomous power of the world's first open-source testing agent.

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.