RESTClient - RESTClient can be used to test variety of HTTP communications and RESTful webservices.
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Postman - The Collaboration Platform for API Development
Runscope - Log, monitor and measure your API usage to solve API problems fast.
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