Postman - The Collaboration Platform for API Development
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Hoppscotch - Open source API development ecosystem
RESTer - A REST client for almost any web service (Firefox and Chrome extension).
soapUI - SoapUI Pro is one of the most prominent API testing platforms around, allowing developers to quickly prototype the functions of their apps and get them to market with little hassle.
Postwoman - An online, open source API request builder