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

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.

REST API client library for .NET

Automate API workflows. Chain HTTP requests. Validate. Zero code.

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.

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