Testing your Web Server Configuration
This is a running list of websites that will, well, test your website for different reasons, mostly security.
List
- securityheaders.com an analyzer and rating system for your HTTP response headers, along with links to how to’s to update your config. 
- CFSSL “CFSSL is CloudFlare’s PKI/TLS swiss army knife. It is both a command line tool and an HTTP API server for signing, verifying, and bundling TLS certificates.” 
- Qualys SSL Labs This is the big behemoth of testing sites. They tend to be considered the defacto-standard for security testing.