Mockoon is the easiest and quickest way to design and run mock REST APIs.

HyperTest is a no-code test automation tool that regresses all your APIs by auto-generating integration tests using your network traffic, also giving a way to reproduce these failures inside actual user-journeys.

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

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

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