HttpWatch - HttpWatch: The ultimate HTTP Sniffer for Chrome, IE and iOS
Graphical HTTP Client - Graphical Http Client is a utility to help you test and interact with REST-based web services.
Postman - The Collaboration Platform for API Development
Hurl.it - Hurl makes HTTP requests.
Insomnia REST - The most intuitive cross-platform REST API Client ð´
RESTer - A REST client for almost any web service (Firefox and Chrome extension).