Simulate APIs, integrations, and environments at enterprise scale.

Free & OpenSource REST API Testing Tool for all levels in a Test Pyramid

Browser and Mobile Automation Test Framework for Node.js

Playwright enables reliable end-to-end testing for modern web apps.

JustJSON is a free, simple tool that lets developers quickly create, store, and manage JSON collections. Add, retrieve, and delete data with ease—perfect for testing, JSON placeholder, or mocking data for your apps.

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.