Postman - The Collaboration Platform for API Development
Insomnia REST - The most intuitive cross-platform REST API Client ð´
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.
Paw.cloud - Paw is a REST client for Mac.
Postwoman - An online, open source API request builder
RESTer - A REST client for almost any web service (Firefox and Chrome extension).