This is an interactive explorer for the Collection+JSON hypermedia. Give it an URL and it will render is as good as it can.
The purpose is twofold: it is a useful tool to inspect collections while developing or debugging an application. At the same time it's useful to show the power of hypermedia by showing how much a generic user agent can do by using only the generic Collection+JSON specification and not knowing anything about your application.
There's a growing C+J community that's discussing on the Google Group.
Reading the (quite light) formal specification is useful. It also has a tutorial and some examples.
Feel to use this service! However, note that it's running on a free Heroku instance so it might fail, be slow or otherwise useless.
If you want to run it against your own local servers you can either run it yourself, or use apps like localtunnel.com to make your application publicly available.
The source code is available here.