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.

API Testing Platform that automatically generates unit test cases with dependency mocks from API calls

Requestly is an open-source tool that simplifies API development, testing, mocking, and integration for developers and QAs.

Real API Design-first Development Platform Design. Debug. Test. Document. Mock. Build APIs Faster & Together.

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

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