It also depends on your environment. On a platform like .Net it's not impossible to get your JS serializer to serialize 64-bit ints and floats as strings while keeping 32-bit and smaller numeric. So no matter how you represent it server-side it will survive a round trip. For a language that doesn't make that kind of distinction in the type system (I'm thinking Python, but I could be wrong), you really have to toString it right when you get it from the database. The only other option is to base the serialization decision on the value, which means sometimes your ids are returned as ints and sometimes as strings. At best it's ugly, at worst it leads to bugs.