Have you ever needed to test a client you were writing but didn’t want to setup or program an HTTP server? Ever worked with an Arduino Yún and wanted to make HTTP calls to a JSON service?
Luckily, the nice people at Runcope run a service called httpbin. When you visit the site, you’ll see a list of various API calls that your client can make, and receive JSON-encoded responses. The APIs are very fast and respond almost immediately (averages 65ms on my computer/connection).
The API calls I found particularly useful were the status calls. You can make a call to http://httpbin.org/status/401 or http://httpbin.org/status/404 and the API will return 401 UNAUTHORIZED or 404 NOT FOUND, respectively.
You may not need the service for anything right away but this is definitely a site to bookmark. Let me know how you would use the service in the comments.