TST Indent Line is a Firefox add-on designed to improve the visual organization of tabs within the Tree Style Tab extension. This tool provides indent lines similar to those found in Visual Studio Code, enabling users to better navigate their tabbed browsing experience. It requires Tree Style Tab versionor later to function properly. The add-on is subscription-based, offering users a personalized touch to their browsing interface.

For users concerned about privacy, it is important to note that the indent lines do not appear in private windows by default. To enable this feature, users must adjust settings in the Add-ons Manager, allowing the TST Indent Line to access private browsing information. This process involves two steps: granting permission for the add-on to run in private windows and enabling additional features through the Tree Style Tab options.