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What is OptGuideOnDeviceModel, and why does Chrome keep putting it back?

By Irshad PC ·

Blue OptGuideOnDeviceModel folder icon, Chrome's on-device AI model. Safe to delete? Partly, with care.
Location
~/Library/Application Support/Google/Chrome/OptGuideOnDeviceModel
Safe to delete?
Partly, with care No personal data, but Chrome re-downloads it. Turn off On-device AI to keep it gone.

OptGuideOnDeviceModel is the folder where Google Chrome keeps Gemini Nano, the AI model behind features like scam warnings and writing help. Nothing personal lives there, so removing it won’t touch your bookmarks or history. Chrome downloads it again while On-device AI is on, though, so the lasting fix is turning that setting off.

What is OptGuideOnDeviceModel?

The name is short for Optimization Guide On-Device Model. Chrome’s component updater installs the model into a folder with that name (Chromium source). On a Mac it sits at the top level of Chrome’s user data folder:

~/Library/Application Support/Google/Chrome/OptGuideOnDeviceModel

Some guides place it inside the Default profile folder instead, but Chromium’s code and a Chrome team member’s own Mac path (Chromium discussion group) put it next to your profiles, not in them.

The big file inside, usually one level down in a version-numbered folder, is weights.bin. That file is the model itself (9to5Google). Google’s Chrome Help page on on-device AI lists the kinds of features that use it: help with writing, scam warnings, page summaries and tab organization. Websites can use it too, through Chrome’s built-in AI APIs, and the first time a site uses one of those APIs, Chrome can download the model (Chrome for Developers).

The parent folder, ~/Library/Application Support/Google/Chrome, holds much more than this model. It also contains your profile, usually a subfolder named Default, with your history, bookmarks and cookies (Chromium docs). Never delete the whole Chrome folder. Chrome’s regular browsing cache is a separate thing under ~/Library/Caches/Google/Chrome (same Chromium doc), an ordinary app cache like the ones on our Library/Caches page.

Chrome isn’t the only app parking AI models on your drive. Our guide to AI app storage on a Mac maps the rest. The Claude desktop app does something similar with its vm_bundles folder.

Is it safe to delete?

You won’t lose anything personal. The folder holds a model Google can send you again, and your browsing data stays in your profile folder. Until the model comes back, though, the features that need it stop working, like on-device scam warnings.

There are two catches. First, Chrome puts it back. As long as On-device AI is on and your Mac meets Google’s requirements, Chrome downloads the model again. Second, Google advises against removing the files by hand. Its help page calls the settings toggle the only supported way to manage these models and says deleting the files yourself may not prevent future downloads. A Chrome developer relations engineer also warned that removing weights.bin can leave the browser in a weird state (Chromium discussion group).

So start with the toggle. Delete the folder by hand only if your Chrome doesn’t have the toggle yet.

Why it gets so big

Almost all the space goes to one file. weights.bin can reach about 4 GB, according to 9to5Google. Google says the exact size changes as Chrome updates the model (Chrome for Developers). Chrome only downloads it when you have roughly 20 GB free, an unmetered network connection and a capable enough Mac (Chrome Help).

Chrome also cleans up after itself when space runs short. Google’s developer docs say Chrome removes the model if free space drops below 10 GB after the download, then fetches it again once you have room (Chrome for Developers). On a nearly full Mac, that can mean the folder comes and goes.

How to clear it yourself

Turn off On-device AI (the supported way)

  1. Open Chrome.
  2. Click the three-dot More menu at the top right, then choose Settings.
  3. Click AI Innovations in the sidebar. Some versions have listed this setting under System instead (MacRumors).
  4. Turn off On-device AI. Chrome deletes the model files and won’t download them again while the setting stays off. Features that rely on the model stop working until you turn it back on (Chrome Help).
  5. To confirm, open Finder, choose Go > Go to Folder, paste ~/Library/Application Support/Google/Chrome and press Return. If OptGuideOnDeviceModel is still there, select it and press Command-I to check its size.

Don’t see the toggle? Choose Chrome > About Google Chrome to update. Google told 9to5Google it began rolling the setting out in February 2026, and that outlet reported Mac users on Chrome 147 couldn’t find it yet in its testing (9to5Google). You can turn the setting back on later, and Chrome will download the model again when your Mac meets the requirements.

Delete the folder by hand (temporary)

  1. Quit Chrome with Command-Q so it isn’t using the files.
  2. In Finder, choose Go > Go to Folder, paste ~/Library/Application Support/Google/Chrome and press Return.
  3. Drag OptGuideOnDeviceModel to the Trash. Leave everything else in that folder alone, especially Default and any Profile folders, which hold your browsing data.
  4. Open Chrome and check that it works. If something’s off, put the folder back from the Trash. If all is well, empty the Trash to get the space back.

Expect the folder to come back later unless On-device AI is off.

What SpaceUp Mac does with it

SpaceUp Mac lists this folder in its Clean tab, in both the App Store and direct-download versions, under “Chrome downloadable components,” along with a few of Chrome’s other re-downloadable component folders. It’s marked Review and stays unticked until you choose it. If Chrome is open when you clean, SpaceUp Mac skips this item and asks you to quit Chrome and clean again. Cleaning clears the contents directly instead of moving them to the Trash (here’s why caches skip the Trash). This item stays out of your profile folders. A separate “Chrome web-app caches” item clears only cache subfolders inside Default (Code Cache, GPUCache and service worker caches) and leaves bookmarks, passwords and history alone. Turn off On-device AI if you want the model to stay gone.

Common questions

Will deleting it remove my bookmarks or history?

No. Those live in your Chrome profile folder, usually Default, which sits beside OptGuideOnDeviceModel rather than inside it. You lose the on-device AI features until the model returns, and that’s it.

Why can’t I find the folder on my Mac?

Chrome downloads the model only when your Mac meets Google’s requirements, including roughly 20 GB of free space (Chrome Help), and it removes the model if free space later drops below 10 GB. To check the model’s status and size, type chrome://on-device-internals into Chrome’s address bar (Chrome for Developers).

Can I block it with chrome://flags instead?

Google names the settings toggle as the only supported method. Flags are experimental switches that can change or disappear between Chrome versions, so they’re not a dependable way to keep the model off.

Is it different on a work Mac?

It can be. Google notes that model downloads follow Chrome Enterprise policy, so your IT team may control this setting on a managed Mac (Chrome Help).