This page covers this website and how to report a vulnerability.
This site sets no cookies, runs no JavaScript and loads nothing from another domain. Fonts are served from this domain, and a content security policy enforces the rest.
There are no forms. Contact is by email.
Write to security@certaintylabs.net with enough detail to understand and reproduce the issue.
Do not access, change, keep or disclose data that is not yours, and do not degrade a service to demonstrate a finding.
The machine-readable contact is at /.well-known/security.txt.