Postman - The Collaboration Platform for API Development
HTTP Debugger - Debug HTTP API calls to a back-end and between back-ends. Easy of use, clean UI, and short ramp-up time. Not a proxy, no network issues!
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Google Chrome Developer Tools - Get started with Google Chrome's built-in web developer tools.
RESTer - A REST client for almost any web service (Firefox and Chrome extension).
Firefox Developer Tools - Examine, edit, and debug HTML, CSS, and JavaScript on the desktop and on mobile.