Right. I was aiming to do it client-side only but I found out that web browsers restrict the headers you have access to through cross-origin XHR requests [1][2].

So it was a trade-off and I preferred showing all the headers at the expense of having to proxy the calls through a server.

[1] http://www.w3.org/TR/XMLHttpRequest/#the-getallresponseheade...

[2] http://www.w3.org/TR/cors/#cross-origin-request

I will make it available on Github later, so that you at least have the option of running it yourself.

For dev or CI you might want to take a look at Gavel https://github.com/apiaryio/gavel (or even Dredd for that matter https://github.com/apiaryio/dredd)

(disclosure: I work for Apiary.io)