Note:

This is a customized version of the addon, forked from the original, though I try to keep it up to date

Customizations include:

• Smaller sidebar (30px wide vs 45px)
• Navbar in titlebar
• Only show tab previews when pinned
• More native feel on MacOS, styled after iMessage
• Fixes for "attention" tabs, such as those sent from another computer

If this sounds good to you, you can download here*

*Please note that this addon will not automatically update, you'll have to keep coming back to update

Original README begins:

TabCenter

Tabbed browsing is a concept that has existed for a long time without being seriously re-evaluated. In that time, browsing behaviors have changed. The web is now the central interaction point on desktop and laptop computers. For many users, their browser is the only application they ever open.

Tab Center is an attempt to solve some of the issues that have emerged from the way people use tabs (most notably the “too many tabs” problem) and provide a more versatile UI basis for future innovation. The first version of this Firefox add-on arranges tabs in a vertical rather than horizontal fashion. It is heavily inspired by and borrows ideas from the excellent VerticalTabs add-on.

Feel free to install the add-on, read the full proposal, or file a new bug! We also have a Contributor’s document, if you want to get involved and maybe fix some bugs.

Incompatibility Notes

We are incompatible with a number of add-ons:

• Hide Caption Titlebar Plus
• HTitle
• Tab Mix Plus
• Tab Groups
  • Tab Groups Helper
• Tree-Style Tabs
• TooManyTabs
• All-In-One Sidebar
• Firebug
• Mozilla Labs: Prospector - LessChrome HD

Please let us know if you find any problems with extensions not mentioned.

Development

After cloning this repository, run npm install and npm install jpm then:

• npm run locales && jpm run to spawn a new Firefox profile with the addon installed
• npm run locales && jpm xpi to generate an installable XPI file locally

Read more about jpm on MDN