A different thread pointed out a couple of services that would require a client MTLS certificate, accept any cert, and then respond with information about the SSL handshake/certs.
HTTPS test server that checks client certificates
These endpoints both return HTML. Does anyone know of anything similar that returns application/json?
The URLs below will return application/json content upon successfully mutual TLS client certificate authentication. If no authentication is peformed, then HTTP error 403 is returned in the HTTP headers and the response is empty:
The json returned in case of success contains various technical information about the established connection.
