Jest is a delightful JavaScript Testing Framework with a focus on simplicity.

Selenium automates browsers. That's it! What you do with that power is entirely up to you.

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

ReadyAPI is a low-code API testing platform for development teams that care about creating test automation across any workflow.

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.

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