Duplicate Tabs Closer

Duplicate Tabs Closer detects and closes duplicate tabs automatically or displays them in a panel for manual review.

• Built with the WebExtensions API
• Supports Chrome, Firefox, Edge, Opera, Vivaldi, and Brave
• Firefox Multi-Account Containers are supported

Supported Browsers

Browser	Store	Notes
Chrome	Chrome Web Store	Full support
Firefox	Firefox Add-ons	Full support including Multi-Account Containers
Microsoft Edge	Chrome Web Store	Full support
Opera	Chrome Web Store	Full support
Vivaldi	Chrome Web Store	Full support
Brave	Chrome Web Store	Full support

Note: The Container scope options are exclusive to Firefox and require the Multi-Account Containers feature. They are not available on Chrome, Edge, Opera, Vivaldi, or Brave.

Accessing Options

The extension offers two configuration interfaces:

• Popup panel: click the extension icon in the toolbar. Provides quick access to a configurable subset of options and the list of current duplicate tabs.
• Options page: click the gear icon (⚙) at the top-right of the popup, or open your browser's Extensions settings and choose Options for Duplicate Tabs Closer. Provides access to all settings.

In the Options page, each option in the Matching rules section has an eye icon (👁) that controls whether that option is visible in the popup panel.

Options

On Duplicate Tab Detected

Controls what the extension does when a duplicate tab is opened.

Value	Description
Do nothing (default)	Monitors tabs and updates the badge counter. No automatic action is taken.
Close tab automatically	Immediately closes the duplicate tab when it is detected.

On Remaining Tab

Only active when On duplicate tab detected is set to Close tab automatically.

Determines what happens to the kept tab after its duplicate is closed.

Value	Description
Do nothing	Nothing further happens after the duplicate is closed.
Activate (default)	Switches focus to the kept tab.
Default tab behaviour	Moves the kept tab to the position of the closed tab and activates it if needed, mimicking the browser's normal tab behaviour.

Intentional Duplicate Protection

Only active when On duplicate tab detected is set to Close tab automatically.

Tabs opened on purpose using the browser's built-in Duplicate Tab command are never auto-closed.

Note: This protection is only available on Firefox. On Chrome, Edge, Opera, Vivaldi, and Brave, tabs opened via "Duplicate Tab" will still be auto-closed because the required browser API is not available on those browsers.

Priority & Exclusions

Determines which of two duplicate tabs is kept when one must be closed, and defines which tabs are excluded from detection entirely. Rules are applied in this order:

1. Pinned tab preference (if Keep pinned tab is enabled)
2. HTTPS preference (if Keep tab with HTTPS is enabled)
3. Age-based preference (Keep older tab / Keep newer tab)
4. Active window preference (if Prioritize active window is enabled and scope covers multiple windows)

Option	Default	Description
Keep older tab	on	Keeps the tab that was opened first.
Keep newer tab	off	Keeps the most recently opened tab.
Keep and reload older tab	off	Keeps the older tab but reloads it with the newer tab's URL. Useful when the newer URL contains updated content such as a redirect destination.
Keep tab with HTTPS	on	When one tab uses HTTP and the other HTTPS for the same URL, the HTTPS tab is kept. Also normalises http:// to https:// during URL comparison so the two are treated as duplicates.
Keep pinned tab	on	A pinned tab is always kept; the unpinned duplicate is closed instead.
Prioritize active window	on	When duplicates span multiple windows and the age-based preference would close the tab in the currently focused window, keeps that tab instead. Only applies when Scope is set to All windows or Container in all windows.

The first three options (Keep older tab / Keep newer tab / Keep and reload older tab) are mutually exclusive. Only one is active at a time.

Skip blank tabs

Available in the Options page only.

When enabled, blank tabs (about:blank and new tab pages) are completely invisible to the extension — they are never shown in the duplicate tabs list, never auto-closed, and never used as a reference when comparing tabs. This is distinct from the whitelist: whitelisted tabs are still detected and shown; skipped blank tabs are not processed at all.

Whitelisted URLs

Available in the Options page only.

A list of URL patterns, one per line. Whitelisted tabs are always detected and shown in the duplicate tabs list, marked with a tooltip indicating they are whitelisted. In Close tab automatically mode, they are never auto-closed. When the Hide whitelisted tabs button is active, they are also excluded from the Close duplicates button in manual mode.

Pattern syntax: * matches any sequence of characters. All other characters match literally. Lines wrapped in /…/ are treated as regular expressions: /^(?!.*google\.com)/ whitelists everything except Google.

https://docs.google.com/*
*://github.com/*/issues
/^(?!.*google\.com)/

Matching Rules

Controls how two tabs are compared to determine whether they are duplicates.

Option	Default	Description
Ignore case in URL	off	Treats uppercase and lowercase as equal (Example.com = example.com).
Ignore 'www' in URL domain name	off	Treats www.example.com and example.com as identical.
Ignore hash part in URL	off	Ignores everything after # (page.html#intro = page.html#setup). Has no effect when Ignore path part is enabled.
Ignore search part in URL	off	Ignores the query string (everything after ?). Has no effect when Ignore path part is enabled.
Ignore path part in URL (domain only)	off	Compares only the origin (scheme + domain), ignoring path, query string, and hash. When this is enabled, Ignore hash part and Ignore search part are redundant.
Compare with title	off	Two tabs are also considered duplicates when their page titles match (see % title similarity below). Useful for pages that display the same title across different URLs.
% title similarity	100	Minimum similarity percentage (1–100) for two titles to be considered a match. 100 requires an exact match (case-insensitive). Only active when Compare with title is enabled.

URL Pattern Rules

A list of URL patterns, one per line. Any two open tabs whose URLs both match the same pattern are treated as duplicates, even if their full URLs differ.

Useful for grouping all tabs from a single service as duplicates of each other regardless of the specific path.

Pattern syntax: * matches any sequence of characters. All other characters match literally.

*://docs.google.com/*
*://github.com/*/pull/*

Title Pattern Rules

Works identically to URL Pattern Rules but is applied to the page title instead of the URL. Any two tabs whose titles both match the same pattern are treated as duplicates.

Pattern syntax: * matches any sequence of characters. All other characters match literally.

* - Gmail
GitHub - *

Pattern syntax note: The Whitelist, URL Pattern Rules, and Title Pattern Rules all use the same simple wildcard syntax. The only special character is *, which matches any sequence of characters (including none). This is not full regular expression syntax. Characters such as ., +, ?, (, ) etc. are matched literally, not as regex metacharacters.

Scope

Defines which tabs are included when searching for duplicates.

Value	Default	Browser	Description
Active window	on	All	Searches for duplicates only within the currently focused browser window.
All windows	off	All	Searches for duplicates across all open browser windows.
Container in active window	off	Firefox only	Duplicates are detected only among tabs that share the same container within the active window. Tabs in different containers are never treated as duplicates of each other.
Container in all windows	off	Firefox only	Same as above but searches across all open windows.

The Container options require Firefox with the Multi-Account Containers feature enabled.

Theme

Available in the Options page only.

Option	Default	Description
Theme	Sky (default)	Visual theme for the extension panel. See Themes below.

Themes

11 themes are available from the Theme dropdown in the Options page:

Light themes: Sky (default), Sage, Rose, Amber, Slate, Violet

Dark themes: Ocean Night, Charcoal, Midnight Purple, Dark Teal, OLED Black

Popup

Available in the Options page only.

Option	Default	Description
Popup layout	Two columns	Layout of the popup panel. Single column shows options above the duplicate tabs list. Two columns shows them side by side.
Close popup after closing duplicate tabs	off	Automatically closes the popup panel after the Close duplicates button is clicked.
Open popup on duplicate detected	off	Automatically opens the popup panel whenever a new duplicate tab is detected. The Options section collapses automatically when the popup is opened this way, giving more space to the duplicate tabs list.

Badge

Available in the Options page only.

Option	Default	Description
Duplicate tabs badge color	#f22121 (red)	Color of the extension icon badge when duplicate tabs are detected.
No duplicate tabs badge color	#1e90ff (blue)	Color of the badge when no duplicates exist. Only relevant when Show badge if no duplicate tabs is enabled.
Show badge if no duplicate tabs	on	Always displays the badge. When off, the badge is hidden entirely when there are no duplicates.

Popup Panel

In the duplicate tabs list, tabs that will be closed show a strikethrough title. The tab that will be kept is shown at full brightness.

• Grouped view: click the group icon in the duplicate tabs footer to switch between flat and grouped views. In grouped view, duplicate tabs are organised by matching rule group, collapsed by default. Each group shows a count badge and a close button to close all tabs in the group at once. Expand/collapse state per group is preserved while the panel is open. The view preference is saved and shared with the options page.

• Hide whitelisted tabs: click the hide-whitelisted icon in the duplicate tabs footer to show or hide whitelisted tabs in the list. When active, tabs whose URLs match a whitelist entry are hidden from the panel. The preference is saved and shared with the options page. When hiding is active, the Close duplicates button also skips whitelisted tabs.

• Hide options column: in two-column layout, click the chevron tab on the left edge of the duplicate tabs column to hide the options column. The popup narrows to focus on the duplicate tabs list. Click the chevron again to restore the options column. The state is saved and restored the next time the popup is opened.

• Shrunk mode: toggle the compress icon in the popup to hide all unpinned sections, keeping the panel compact. Sections can be pinned with the pin icon (📌) in the popup panel so they stay visible when shrunk mode is active.

• Pause monitoring: click the pause icon in the popup or options page header to temporarily stop duplicate tab detection. While paused:

  • The extension icon badge shows "⏸" on a grey background
  • The pause button turns amber so the paused state is always visible
  • The mode is automatically set to "Do nothing"
  • The "On duplicate tab detected" setting is disabled
  • No new duplicate tabs are detected or closed
  • Click the play icon or use the keyboard shortcut to resume

• Popup visibility (eye icon): in the Options page, each option in the Matching Rules section has an eye icon (👁). Enabling it makes the option visible in the popup panel; disabling it hides it.

Matching Rules option	Visible in popup by default
Ignore case in URL	No
Ignore 'www' in URL domain name	No
Ignore hash part in URL	No
Ignore search part in URL	No
Ignore path part in URL	Yes
Compare with title	Yes
URL pattern rules	Yes
Title pattern rules	No

Hotkeys

No default keyboard shortcuts are set to avoid conflicts with browser built-ins. You can assign custom shortcuts in your browser settings:

Command	Description
Close all duplicate tabs	Closes all currently detected duplicate tabs
Toggle auto-close / manual mode	Switches between auto-close and manual mode
Pause or resume duplicate tab monitoring	Temporarily stops and restarts detection

To configure shortcuts:

• Chrome / Edge / Brave / Vivaldi: open chrome://extensions/shortcuts
• Opera: open opera://extensions/shortcuts
• Firefox: open about:addons, click the gear icon, then choose Manage Extension Shortcuts

Building

A build script is included that packages the extension for each browser.

Requirements: Windows with PowerShell (built-in on Windows 7 and later).

Run from the repository root:

build\build.bat

Or run the PowerShell script directly:

# Build both Chrome and Firefox packages (default)
powershell -ExecutionPolicy Bypass -File build\build.ps1

# Build Chrome only
powershell -ExecutionPolicy Bypass -File build\build.ps1 -Target chrome

# Build Firefox only
powershell -ExecutionPolicy Bypass -File build\build.ps1 -Target firefox

Output files (created in the repository root):

File	Browser
duplicate-tabs-closer-chrome.zip	Chrome, Edge, Opera, Vivaldi, Brave
duplicate-tabs-closer-firefox.xpi	Firefox