Hand-crafted lightweight Rest Client for testing APIs. Supports collections, environments, git collaboration and local storage.

Built for developers and testers alike, SoapUI is the only open source tool that covers the entire testing spectrum (functional, security, load, mocking).

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

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

Monitor network requests and API failures with real-time insights

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.