I built Tab Merger, a Chrome extension that merges all your windows into one

I built Tab Merger, a Chrome extension that moves the tabs of every open window into the one you’re using. It’s free and open source, like Skillscout and Soundscape.

Chrome windows pile up. A link opens in a new window, you drag a tab out to see two pages side by side, and a few hours later there are five windows with a handful of tabs each. Safari has a Merge All Windows command for this. Chrome doesn’t, so you drag the tabs back one at a time.

Tab Merger is that missing command. Click its button or press Alt+Shift+M, and every tab lands in the window you’re in.

Here it is in 30 seconds:

What it does

Click the Tab Merger button in the toolbar, and the tabs of every other window move into the window you’re using. The windows they came from close, since they’re empty now.

The keyboard shortcut does the same: Alt+Shift+M on Windows and Linux, Option+Shift+M on a Mac. You can change it in chrome://extensions/shortcuts. Look there too if the shortcut does nothing, because Chrome leaves it empty when another extension already uses it.

The tabs keep their order. They arrive window by window, each in the place it had. Tab groups come over whole, with their name and color, and pinned tabs stay pinned.

Incognito tabs never mix with your regular ones. Chrome doesn’t run extensions in incognito unless you allow it, and if you do, Tab Merger in an incognito window merges only the incognito windows. Popups and installed web apps are left alone.

One permission

Tab Merger asks Chrome for a single permission, tabGroups, which lets it move tab groups. Moving tabs needs no permission at all.

So it can’t see the address or the title of your tabs, and it can’t read your pages or your history. It never goes online, and there are no accounts or analytics.

Under the hood

The whole extension is one service worker, background.js: about 40 lines of JavaScript, with no build step.

The shortcut is Chrome’s special _execute_action command, so pressing it fires the same action.onClicked event as clicking the button, with the window you’re in. Tab Merger then goes through every other normal window with the same incognito state. It moves runs of ungrouped tabs with chrome.tabs.move, and each group in one go with chrome.tabGroups.move, which is how a group keeps its name and color.

Chrome unpins a tab when it moves to another window, so Tab Merger remembers which tabs were pinned and pins them again at the end.

The repo has a test that loads the extension into Chromium with Playwright. It opens three windows with a pinned tab and a tab group, merges them, and checks the order of every tab. Chrome 137 stopped accepting the --load-extension flag, so the test loads the extension through the DevTools protocol, with Extensions.loadUnpacked. It runs on every push.

Get it

The code is on GitHub at flaviocopes/tabmerger, MIT licensed.

Tab Merger isn’t on the Chrome Web Store, so you load it into Chrome yourself:

1. Download Tab-Merger-1.0.0.zip from the latest release and unzip it.
2. Move the Tab-Merger-1.0.0 folder somewhere it can stay, like your Documents folder. Chrome runs the extension from that folder.
3. Open chrome://extensions and turn on Developer mode in the top right corner.
4. Click Load unpacked and pick the folder.
5. Click the puzzle icon in the toolbar and pin Tab Merger.

An extension you load this way doesn’t update itself. When a new version comes out, copy its files over the old ones in the same folder, then click the reload arrow on the Tab Merger card in chrome://extensions. The README has the details.

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