HttpWatch - HttpWatch: The ultimate HTTP Sniffer for Chrome, IE and iOS
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Postman - The Collaboration Platform for API Development
Hurl.it - Hurl makes HTTP requests.
Fiddler - Fiddler is a debugging program for websites.
Cocoa Rest Client - A free open source, native Apple OS X app for testing HTTP/REST endpoints