Editors' Note: The Download Now link will prompt a local download of the Firefox extension. To install the extension directly, open the file using your Firefox browser.
A developer tool for interacting with Web services and other Web resources that lets you make HTTP requests, set the entity body, and content type. Poster allows you to interact with Web services and inspect the results. After you install it, just go to View, Sidebar, and Poster to open the tool as a sidebar. After that, try a get or post on your favorite Web service or site.