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

Bruno is a Fast and Git-Friendly Opensource API client, aimed at revolutionizing the status quo represented by Postman, Insomnia and similar tools out there.

Robot Framework is a generic open source automation framework. It can be used for test automation and robotic process automation (RPA).

Puppeteer is a Node.js library which provides a high-level API to control Chrome/Chromium over the DevTools Protocol.

Browser and Mobile Automation Test Framework for Node.js

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