How Firefox Native Vertical Tabs Organize Your Sidebar

This article provides a complete overview of how the native Vertical Tabs feature in the Firefox web browser structures and manages open tabs. It covers the layout mechanics of the sidebar, including the separation of pinned and regular tabs, collapsible view states, overflow scrolling, visual indicators, and the integration of browser tools within the vertical pane.

Collapsible Sidebar States

Firefox organizes vertical tabs within a dynamic sidebar that operates in two primary modes: collapsed and expanded.

  • Collapsed State: Tabs are stacked in a single vertical column displaying only the website favicons. This minimizes horizontal screen usage while keeping tabs accessible.
  • Expanded State: Toggling the sidebar open reveals the full tab width, displaying the favicon, the readable page title, and a close button for each individual tab. Users can also manually resize the width of this pane by dragging its border.

Pinned Tabs vs. Regular Tabs

To keep critical websites accessible, Firefox divides the vertical tab list into two distinct zones:

  • Pinned Tabs: Located at the very top of the sidebar, pinned tabs are organized into a compact grid of favicons. They remain permanently anchored in place and do not move when you scroll through the rest of your open tabs.
  • Regular Tabs: Positioned directly beneath the pinned tab area and separated by a subtle horizontal divider, standard tabs are listed vertically in a single column. Users can drag and drop these tabs up or down to manually reorder their workflow.

Overflow and Independent Scrolling

When you open more tabs than can fit on the screen vertically, the regular tab section becomes an independent scrollable list. Unlike horizontal tabs, which shrink until the text disappears, vertical tabs maintain a consistent height and readable title length regardless of how many tabs are open. The "New Tab" button remains anchored directly beneath the tab list, shifting to the bottom of the pane once the list fills the vertical space.

Visual Indicators and Containers

Firefox uses the horizontal space within each vertical tab row to organize contextual information cleanly:

  • Audio Controls: Tabs actively playing media display a speaker icon next to the site favicon or on the right edge of the tab, allowing you to mute or unmute audio with a single click without switching tabs.
  • Multi-Account Containers: Tabs opened inside Firefox Containers are organized with a distinct, color-coded vertical bar along the edge of the tab, making it easy to visually group work, personal, or shopping tabs within the same vertical list.
  • Unread and Loading States: Loading animations and unread tab indicators replace or badge the favicon directly, keeping status updates aligned in a single vertical column for quick scanning.

Integrated Sidebar Tools

The native vertical tabs implementation shares the sidebar space with Firefox's utility tools. Anchored at the bottom (or top, depending on customization) of the sidebar is a dedicated toolbar containing icons for History, Bookmarks, Tabs from Other Devices, and the AI Chatbot. Selecting any of these tools opens a secondary panel alongside your vertical tabs, allowing you to organize bookmarks or search history without hiding your open tab list.