cerdicator by ishygddt_

[Alpha Release, testers only!]
This software enhances the display of TLS connections by displaying at-a-glance the Root Certificate Authority that your browser trusts to certify the connection. Future releases will include country-of-jurisdiction display, enhanced and user-friendly certificate pinning, and other requested features.

For maximum effectiveness, replace the blank, empty spacer between your URL bar and the navigation buttons (that comes OOTB in Firefox) with this add-on's badge.