Postman is an API platform for building and using APIs. Postman simplifies each step of the API lifecycle and streamlines collaboration so you can create better APIs—faster.

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

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

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

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

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