chrome-nano-detector

Find Google's Gemini Nano on your Chromium-family browser. 80 lines of Node, zero dependencies, MIT.

Some Chromium browsers (Chrome, Edge, Brave, Chromium itself) silently download a ~4 GB on-device LLM called Gemini Nano into a folder named OptGuideOnDeviceModel inside your browser profile. There's no consent prompt — many users don't know it's there. This script finds it on your machine.

Run

npx github:Tensorboyalive/chrome-nano-detector

Or clone + run:

git clone https://github.com/Tensorboyalive/chrome-nano-detector.git
cd chrome-nano-detector
node detector.mjs

Requires Node 18 or later. No npm install needed.

What you'll see

If your machine is clean (no Nano found):

chrome-nano-detector — darwin
────────────────────────────────────────
  Browsers/profiles inspected: 4
    • Chrome   /Users/you/Library/Application Support/Google/Chrome
    • Chromium /Users/you/Library/Application Support/Chromium
    • Edge     /Users/you/Library/Application Support/Microsoft Edge
    • Brave    /Users/you/Library/Application Support/BraveSoftware/Brave-Browser

  ✓ No OptGuideOnDeviceModel folder found.
    Your disk is clean — this Chromium-family browser has not pulled the on-device model here.

If Nano was downloaded:

  ⚠ Found 1 OptGuideOnDeviceModel folder(s):

    [Chrome · profile: Default]
      ~/Library/Application Support/Google/Chrome/Default/OptGuideOnDeviceModel
        → ~/.../OptGuideOnDeviceModel/2025.8.8.1141/weights.bin  3.94 GB
        ── total: 3.94 GB

  Combined size across all findings: 3.94 GB

Exit code is 0 if clean, 1 if Nano was found (so it can be used in CI / scripts).

How to disable

If you want Nano gone:

1. Open chrome://flags (or edge://flags, brave://flags).
2. Search "Optimization Guide On Device Model".
3. Set to Disabled.
4. Restart the browser.
5. Delete the OptGuideOnDeviceModel folder (the script prints the path).

The flag must be off first, otherwise the browser re-downloads on next start.

What it scans

Platform	Browsers
macOS	Chrome (stable, beta, dev, canary), Chromium, Edge, Brave
Linux	Chrome, Chromium, Edge, Brave
Windows	Chrome (stable, beta), Edge, Brave

It walks each browser's user-data-dir, finds profile dirs (Default, Profile 1, …), and looks inside for OptGuideOnDeviceModel/<version>/weights.bin. Reads file sizes from fs.statSync only — does not open or transmit any file content.

Privacy

This script reads file metadata only. It never opens the model file, transmits anything over the network, or writes anywhere on your disk. The whole tool is one 80-line file; audit it before running.

License

MIT. See LICENSE.

Built as part of TensorBoy's one-person AI company OS. PRs welcome — particularly for Vivaldi, Opera, and any Chromium-family browsers I missed.