Cocoa Rest Client - A free open source, native Apple OS X app for testing HTTP/REST endpoints
Postman - The Collaboration Platform for API Development
SoapSonar - Crosscheck Networks designed SOAPSonar from the ground-up as a comprehensive testing solution with...
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Hurl.it - Hurl makes HTTP requests.
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.