Level 32
IndicateTLS is a browser extension for the Firefox web browser that highlights the security protocol that a website uses in the Firefox address bar. Additionally, it provides detailed security information about certain security features and the protocol.

If you see HTTPS in the Firefox address bar you know that the connection to the site is encrypted. While that is good, it is not clear immediately which protocol version browser and site negotiated for the connection.

Browser makers like Mozilla have plans to drop support for old security protocols, TLS 1.0 and TLS 1.1 in particular; the deprecation has been delayed due to Coronavirus but TLS 1.2 and 1.3 will become the standard protocols for all sites going forward.

Browsers don't show whether a connection uses TLS 1.2 or 1.3 by default. As a Firefox user, you may right-click on the page, select Page Info and switch to the Security tab to see the technical details of the connection. These include which security protocol version is used.

The Firefox add-on IndicateTLS brings the information to the forefront. The extension displays the version of the protocol in the Firefox address bar next to the bookmarks icon.

firefox indicate tls

There you find listed the version, e.g. 1.2 as in the example screenshot above. A click on the icon displays technical details. These include at the time of writing:
  • The protocol that is used.
  • The connection state, e.g. secure.
  • The cipher suite.
  • Whether Forward Secrecy is enabled.
  • Whether HSTS preload is enabled.
  • Information about the certificate.
Switch to the resources tab in the interface to display information about loaded resources and technical details for each.

firefox tls resources information

Links to the SSL testing site SSL Labs are provided to run additional tests and get more information about the status of a connection.