[crayonixel]

The source code (JavaScript) is quite readable.

This seems to be the backing store:

https://www.jsonstore.io/9cfa993cd55704f2254949dc21a5f3a7a63...

With the ability to get a specific key from this style of URL:

https://www.jsonstore.io/9cfa993cd55704f2254949dc21a5f3a7a63...

And post to it to set a value.

There's no security though - anyone can overwrite any URL - e.g. in the console on that page:

    pushJSON(endpoint + '/AAAAaaAaAaaAAaaAAAAAaAAAAaAAaAAaaaAAAAaA', 'http://www.example.com/');

[fortyseven]

Looks like there's a limit to the number of urls shortened... it's throwing out the old ones. Womp, womp. :P

[nyanloutre]

Or some people are Curling random stuff into the JSON endpoint