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

Mock and modify HTTP request for exploratory testing.

A browser extension and Ruby gem to improve the debugging experience when testing Rails applications

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.

Browser and Mobile Automation Test Framework for Node.js