[stanleydrew]

What do you mean by visible? Visible in the URL bar of a browser? The headers are all there in the request, for all to see.

[rubyrescue]

yes i'm thinking more pragmatically. From an API perspective the header is part of the request but given that the human-readability of urls is a feature of http, it just somehow feels wrong to me to modify the response based on a request header.

[glassx]

I think most developers don't see that as a problem.

We modify the response all the time based on headers like User-Agent, Referer, If-Unmodified-Since, Accept-Language and others, so using Accept for versioning isn't really that strange.

[Dylan16807]

User-Agent: modifying based on this is a Bad Thing

Referer, If-Unmodified-Since: these only decide if you respond or don't or error, they don't generally change a successful transfer

Accept-Language: I was under the impression that this was buggy and not well-supported, but it is a good example in theory

[icebraining]

The response is changed all the type depending on the value of the Cookie header.