HTTPS test server that checks client certificates

I have written a web service client that uses SSL client certificates to authenticate to the remote server. But since the actual web service is not yet available to me, I'm looking for a public test server that accepts a client certificate for authentication, so that I can test the SSL part of my client for correct implementation and configuration.

I have tried https://requestb.in but it replies with HTTP status 403 (Forbidden) when I use a client certificate. And https://httpbin.org/ accepts my request but doesn't give any indication if the certificate was usable.

Is there a similar service that checks the SSL client certificate?