HTTP Observatory

URL: https://developer.mozilla.org/en/observatory

Checks a site’s security-related HTTP headers.

Cookies
Redirection
Referrer Policy
HTTP Strict Transport Security (HSTS)
Cross-Origin Resource Sharing (CORS)
Cross-Origin Resource Policy (CORP)
Content Security Policy (CSP)
Subresource Integrity (SRI)
X-Content-Type-Options
X-Frame-Options

Here’s a sample report for my domain:

Screenshot of report for www.unindented.org, with a score of A+.