Hey! Thx for the feedback. I was indeed a little bit torn between a GET and a POST for this call and this is my first attempt at a RESTful service so I welcome input. I guess my reasoning here is, that this doesn't actually change anything on the server. Since Instawallets are just random links, they are not really "created".

So in that light, if you had a call to /api/random_number would you make it a GET or a POST? (honest question).

And a question about "idempotency": I agree with the general concept, but wonder about situations like this: Let's say you have a /api/current_time call. I would model that as a HTTP GET, even though it doesn't seem idempotent to me - two calls will return different times. Or is it idempotent in the sense, that theoretically the calls could return the same data if you would execute them fast enough?