What are some alternatives?
Runscope - Log, monitor and measure your API usage to solve API problems fast.
Postman - Postman is the most efficient way to test, develop and document APIs.
Paw - Paw is a REST client for Mac.
Amazon API Gateway - Create, publish, maintain, monitor, and secure APIs at any scale
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.
WireMock - WireMock - a web service test double for all occasions.