Switch Tab with Ctrl+Number

I made a tiny Firefox extension.

On Windows and macOS, Firefox lets you jump to tabs with Ctrl+1 … Ctrl+8, and Ctrl+9 jumps to the last tab. On Linux? Nope. That bugged me enough that I just fixed it myself.

So this extension does exactly one thing:

• Ctrl+1 … Ctrl+8 switch to tab 1-8
• Ctrl+9 switch to the last tab

No toolbar button, no settings page, no tracking. It just listens for those shortcuts and activates the right tab in the current window.

Download

Download switch-tab-ctrl-number-1.0.0.xpi (v1.0.0, Firefox 109+)

Install

Firefox doesn't let you install random .xpi files with one click from a personal site, so:

1. Download the file above.
2. Go to about:addons in Firefox.
3. Click the gear icon → Install Add-on From File…
4. Pick the downloaded .xpi and confirm.

Or drag-and-drop the .xpi file onto a Firefox window.

After that, just press Ctrl+1 … Ctrl+9 and enjoy Windows-style tab switching on Linux.

Source code

The whole thing is two files. That's it.

background.js:

const switchToTab = async (slot) => {
  const tabs = await browser.tabs.query({ currentWindow: true });
  if (tabs.length === 0) return;
  const ordered = tabs.slice().sort((a, b) => a.index - b.index);
  const target = slot === 9 ? ordered[ordered.length - 1] : ordered[slot - 1];
  if (target) await browser.tabs.update(target.id, { active: true });
};

browser.commands.onCommand.addListener((name) => {
  const match = /^switch-to-tab-([1-9])$/.exec(name);
  if (!match) return;
  switchToTab(parseInt(match[1], 10));
});

manifest.json:

{
  "manifest_version": 3,
  "name": "Switch Tab with Ctrl+Number",
  "version": "1.0.0",
  "description": "Switch tabs with Ctrl+1..8 (and Ctrl+9 for last tab) on Linux Firefox, matching the Windows/macOS behavior.",
  "browser_specific_settings": {
    "gecko": {
      "id": "switch-tab-ctrl-number@dmitryside",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "commands": {
    "switch-to-tab-1": {
      "suggested_key": {
        "default": "Ctrl+1"
      },
      "description": "Switch to tab 1"
    },
    "switch-to-tab-2": {
      "suggested_key": {
        "default": "Ctrl+2"
      },
      "description": "Switch to tab 2"
    },
    "switch-to-tab-3": {
      "suggested_key": {
        "default": "Ctrl+3"
      },
      "description": "Switch to tab 3"
    },
    "switch-to-tab-4": {
      "suggested_key": {
        "default": "Ctrl+4"
      },
      "description": "Switch to tab 4"
    },
    "switch-to-tab-5": {
      "suggested_key": {
        "default": "Ctrl+5"
      },
      "description": "Switch to tab 5"
    },
    "switch-to-tab-6": {
      "suggested_key": {
        "default": "Ctrl+6"
      },
      "description": "Switch to tab 6"
    },
    "switch-to-tab-7": {
      "suggested_key": {
        "default": "Ctrl+7"
      },
      "description": "Switch to tab 7"
    },
    "switch-to-tab-8": {
      "suggested_key": {
        "default": "Ctrl+8"
      },
      "description": "Switch to tab 8"
    },
    "switch-to-tab-9": {
      "suggested_key": {
        "default": "Ctrl+9"
      },
      "description": "Switch to last tab"
    }
  }
}

No bundlers, no minified blob, no network requests. It queries the tabs in the current window, picks the one at the requested index (or the last one for Ctrl+9), and activates it.

Check it yourself

An .xpi is just a .zip. You don't have to trust the code block above. Inspect the exact file you're installing:

# 1. Download it, then list what's inside
unzip -l switch-tab-ctrl-number-1.0.0.xpi

# 2. Unpack it somewhere
mkdir ext-src && unzip switch-tab-ctrl-number-1.0.0.xpi -d ext-src
ls -R ext-src

# 3. Read the actual code
cat ext-src/manifest.json
cat ext-src/background.js

You'll see background.js, manifest.json, plus a META-INF/ folder. That folder (cose.sig, mozilla.rsa, etc.) is Mozilla's signature — it's what lets Firefox install the file without complaining about it being unsigned. You can ignore it for review purposes; the executable part is only the two files above.

Optional, verify the download wasn't corrupted/tampered with in transit:

sha256sum switch-tab-ctrl-number-1.0.0.xpi
# expected: 239813cbb50b615608527fd364bab75ea6c1e853b6266cc58e6ab5b579e4e90c

If the hash matches and the two source files match what's posted here, you're running exactly what I wrote.