Postman - The Collaboration Platform for API Development
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Sauce Labs - Test mobile or web apps instantly across 700+ browser/OS/device platform combinations - without infrastructure setup.
RESTer - A REST client for almost any web service (Firefox and Chrome extension).
TestComplete - TestComplete Desktop, Web, and Mobile helps you create repeatable and accurate automated tests across multiple devices, platforms, and environments easily and quickly.
Postwoman - An online, open source API request builder