Tab Title Prefix от ishizakahiroshi

Tab Title Prefix makes similar tabs easier to tell apart.

In Firefox, the extension can automatically add the current Multi-Account Containers name to the beginning of each tab title. You can also create URL rules such as https://example.com/* and add a custom prefix.

Features
Automatic container prefixes for Firefox Multi-Account Containers
Custom URL rules with user-defined prefixes
Rule editing, reordering, enable and disable controls, and pause-all support
Preview the resulting title before saving a rule
Reapplies prefixes when a single-page app changes route or rewrites the page title
Updates already-open tabs when a container is renamed
Local options for the extension toggle, container template, and URL rules

Privacy
Tab Title Prefix does not collect or transmit personal data. Settings stay in Firefox local storage, and title updates happen locally in the page. Because a tab title is part of the page DOM, a website you visit can read the resulting title through document.title. Avoid sensitive container names or use a neutral custom prefix.

Supported platform
Firefox for desktop. The container integration requires Firefox Multi-Account Containers. Pages where Firefox does not allow extensions to run cannot be modified.