IPv6 support would be great (take a look at what http://icanhazip.com does: http://ipv4.icanhazip.com and http://ipv6.icanhazip.com)

Anyway, sounds really cool :)

Endpoints to test various SSL/TLS/X.509 stuff would be super helpful. Call would returning a stock HTTP response body, but with different changes to the SSL/TLS handshake (you will have to use different host names to do this)

https://expired.x509.httpbin.org/ - returns an otherwise valid cert that has expired

https://wrongcn.x509.httpbin.org/ - returns an otherwise valid cert with a different CN name

https://sslv3.tls.httpbin.org/ - only negotiates an SSLv3 connection

https//3des.tls.httpbin.org/ - only negotiates to use 3DES as the cipher

I've wanted the ability to combine things – e.g. setting headers on a non-200 response. It'd be nice if there was a way to combine supported options into a single request or at least as many as will fit in to the querystring.

I'd like to see a method-neutral version of /get, /post, /patch et al - i.e. one that responds no matter what HTTP method is passed.

The response would then include "method": "BLAH" k/v indicating the method that was used.