My personal choice: Talend API Tester - Free Edition (formerly called 'Restlet'). It's straightforward, and (most importantly for me) works seamlessly through

My personal choice: Talend API Tester - Free Edition (formerly called 'Restlet'). It's straightforward, and (most importantly for me) works seamlessly through a corporate proxy. I also like it's approach for having a hierarchical tree of saved queries, which can be easily exported and traded between developers (I'm sure there are superior, centralised solutions but this works well in our team).