[toolslive]

For CSV, I don't know how this comes out. It depends on the library/programming language. It might be 73786976294838210000 or it might throw an exception, or whatever. I'm just saying JSON will not solve your problems neither.

[andix]

So it always depends on the implementation.

If you need something unambiguously specified, then XML with XSD is still a valid option. All number types are specified exactly, and you can use extensions for custom number types.

[toolslive]

what's wrong with protobuf & friends ?

[andix]

Nothing. Not a very good data exchange format though.