HTTP Version Indicator by Patrick Dark

Adds a color-based indicator for the HTTP version of the top‐level document of a tab in the address bar. Green indicates HTTP 3.0, cyan indicates HTTP 2.0, yellow indicates HTTP 1.1, orange indicates HTTP 1.0, and white indicates an unknown HTTP version.

The network.http.http3.enabled about:config preference must be enabled for Firefox to make HTTP 3.0 connections. Sites known to use HTTP 3.0 include Cloudflare, Facebook, Google, Google News, Google Translate, Instagram, Microsoft News, Windows Blogs, and YouTube as well as some Cloudflare-hosted sites that have apparently opted into the functionality, such as Android Police. Certain applications may block HTTP 3.0 connections in Firefox, such as Avast Free Antivirus.

Note that indicator icons will not appear on pages loaded via service workers unless the dom.serviceWorkers.enabled about:config preference is disabled. If that preference is disabled after one has already loaded such a page, one may need to bypass their browser cache by, for example, accessing the relevant page and pressing Ctrl+F5 to get the indicator icon to appear. Sites known to use service workers include Fastmail, Gmail, Mozilla Discourse, and Twitter.

Also note that a page must be loaded after the extension is enabled for indicator icons to appear.

Known Issues:

• The indicator icon isn't displayed on some addons.mozilla.org pages.
• The indicator icon background color is only optimized for Firefox's native dark theme and may appear excessively dark when paired with lighter themes.
• The extension is only localized for English.