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.

Simulate APIs, integrations, and environments at enterprise scale.

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

With over 120,000 users, Fake Filler is the most popular browser extension for testing forms. Fake Filler is the quickest way to fill all inputs on a page with fake data.

A tool to help create test data via a UI or API

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