Chrome Is Secretly Downloading a 4GB AI File on Your Computer Without Permission

Google’s Chrome browser has been quietly downloading a large AI file onto people’s computers, without asking, without any pop-up, and without telling you it happened. If you find the file and delete it, Chrome just downloads it again. I have detailed out the news so here is what is going on and what you can do.

What Is Actually Going On?

• Chrome downloaded a 4GB file onto your computer in the background
• The file is called weights.bin and sits in a folder called OptGuideOnDeviceModel
• It belongs to Google’s AI system called Gemini Nano
• Chrome never asked. No pop-up. No notifications. Nothing
• If you delete it, Chrome downloads it again
• This affects Chrome 147 and later on Windows and Mac

Gemini Nano is an LLM (large language model) optimized for local inference for AI writing, summarization, translation, and scam detection etc. It runs entirely on the device without sending data to Google’s servers.

The file belongs to Google’s AI system called Gemini Nano. It is designed to run AI features directly on your computer. Things like helping you write text, summarizing web pages, and detecting scam websites.

Who Found This and How

Between April 20–29, 2026, users and researchers began noticing that Google Chrome had silently downloaded a large language model (LLM) file onto their devices. The story exploded publicly between May 4-6, 2026, after security researcher Alexander Hanff, known online as “That Privacy Guy“. He published his findings and went viral on social media. Posts across the internet warned the file could be “spyware,” triggering widespread concern.

Here is exactly how he found it:

• He created a completely fresh Chrome profile to isolate Chrome’s behaviour
• He monitored filesystem activity logs in real time
• He watched Chrome silently create the OptGuideOnDeviceModel folder
• The full 4GB file downloaded with zero user interaction
• The entire process took just 14 minutes and 28 seconds
• Chrome had already checked the computer’s hardware specs before starting

This was not a bug. Chrome deliberately decided the machine was eligible and started downloading without telling anyone.

He then deleted the file manually, restarted Chrome, and it downloaded again. Automatically. No notification.

Wait, Is My Data Being Sent to Google?

Google’s justification for putting the AI on your device is actually a privacy argument. Local AI means your data stays on your machine, not in the cloud. That sounds reasonable. But here is the twist:

• The AI Mode button in your Chrome address bar, the one you actually see and use, does not use the local model
• That feature still sends your queries to Google’s cloud servers
• The 4GB file on your drive powers background features most users never touch

So you are carrying the storage cost. Google is still getting your data from the feature you actually use.

Is This Legal?

Alexander Hanff does not agree with this, especially in Europe. He has officially accused Google of breaking European privacy laws. He says Google forced users to download a large amount of data without telling them clearly or asking for permission. He also believes that sending 4GB of data to millions of Chrome users may cause between 6,000 and 60,000 metric tons of CO2 pollution.

European laws like the GDPR and the ePrivacy Directive say that companies must be honest and take proper permission before storing anything on a person’s device. Hiding this information in Chrome’s Terms of Service is not considered real permission.

This is also not only Google’s problem. Malwarebytes reported that Hanff earlier found that Anthropic’s Claude Desktop app secretly installed browser files on a user’s computer. It even added files for five browsers that were not installed on the system. If the user deleted the files, they would come back again.

The above laws require companies to be transparent, but Data Privacy is a joke.

What Google Said

Google confirmed the file is real and intentional. A spokesperson said:

“We have offered Gemini Nano for Chrome since 2024 as a lightweight, on-device model. It powers important security capabilities like scam detection and developer APIs without sending your data to the cloud. In February, we began rolling out the ability for users to easily turn off and remove the model directly in Chrome settings. Once disabled, the model will no longer download or update.”

Important detail:

• The opt-out option came in February 2026
• The mass rollout of the 4GB file began in late April 2026
• Millions of users already had the file before any opt-out was even available to them

Does This Affect You?

Most likely yes, if you use Chrome on a Windows or Mac computer. Chrome 147 and later versions triggered the mass rollout. You can check right now by typing chrome://on-device-internals into your Chrome address bar and looking for the model status.

On Windows, the file lives at: %LOCALAPPDATA%\Google\Chrome\User Data\OptGuideOnDeviceModel

On Mac and Linux, look inside your Chrome User Data folder for the same OptGuideOnDeviceModel directory.

How to Remove It

Deleting the file alone will not work. Follow these steps in order:

Step 1. Turn off via Settings Go to Chrome Settings, then System, then find the “On-device AI” toggle and switch it off. This is the simplest method.

Step 2. Turn off via Flags If the toggle is not visible, type chrome://flags in your address bar, search for “optimization guide on device,” set it to Disabled, and restart Chrome.

Step 3. Delete the folder Once the feature is disabled, go to the OptGuideOnDeviceModel folder on your drive and delete it. Now it stays gone.

Step 4. Block re-installation As an extra step, you can change the weights.bin file to read-only before deleting the folder, which prevents Chrome from writing it back.

One side effect to know: Turning this off disables Chrome’s on-device scam detection and the “Help me write” tool. If you use either feature, weigh that before removing it.

The Bottom Line

Chrome holds more than 64 percent of the global browser market. This was not a small test. It was a worldwide rollout of AI software onto personal devices, done silently, with no consent screen shown to anyone.

• Your storage was used without permission
• Your bandwidth was consumed without permission
• Your electricity powered the download without permission

Google had the option to ask first. It chose not to. That is what this story is really about.