While i was messing around with another app , what i saw was that parse apps leak their clientkeys but not the application Id. I did look more into it . parse does some sort of hashing to make an iid which is sent with each request . I am pretty sure that the iid is made from the app key and the client key. I did mess around a lot with an app using parse with charles web proxy and a number of decompilation tools i plan to write about it soon. ( as soon as i get something concrete)