Chrome silently installs a 4 GB local LLM on your computer

Google Chrome will steal 4 GB of disk space from your computer for its local large language model unless you opted out. It's called weights.bin and it's stored in a folder called OptGuideOnDeviceModel. What's more, if you track down the file and delete it, Chrome will download a fresh copy and reinstate it. The discovery was announced this week by Alexander Hanff, who blogs as "the Privacy Guy," in a somewhat sensationally titled blog post: Google Chrome silently installs a 4 GB AI model on your device without consent. At a billion-device scale the climate costs are insane. It doesn't seem to be new, though: there are signs that Chrome has been doing this for quite some time. In April 2025, this Reddit post suggests the model was "just" 3 GB, but a Stack Overflow question says that by November 2025 it was already up to 4 GB. We would not be at all surprised if soon it went to five. This the what Google calls the "Nano" version of its Gemini local LLM, which powers its Prompt API. That page links to general info about Google's Gemini LLM, but the site about its use on Android has some specific info about Gemini Nano. The Reg FOSS desk is an unapologetic AI skeptic and disabled every option they could find pertaining to AI usage in Chrome as early as possible, and as far as we can see, we did not have the local model installed on any of our computers. For instance, on our increasingly geriatric iMac, we checked with this macOS terminal command: find ~/Library/Application\ Support/Google/Chrome -size +1G -ls 2>/dev/null We also searched the entire C: drive of a ThinkPad reinstalled with Windows 10 IoT LTSC last year and there was no weights.bin anywhere. If you didn't opt out, Google has some info on how to disable it. In brief: in Chrome's address box, enter the special URL chrome://flags. In the resulting page, look for an entry named optimization-guide-on-device-model and set it to Disabled, then restart Chrome. The browser should then delete the weights.bin file. In theory, you can also use your OS to block this – or deploy enterprise policies, if you're free to set your own. (With any luck, soon this will be part of the Just The Browser policy that we reported on in January.) The Reddit post we linked above says that Windows users can set a Registry key. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome, create a DWORD key called GenAILocalFoundationalModelSettings and set it to 1, then restart Chrome. We've not tried this ourselves – our barely used Windows install doesn't have a Google tree in there at all. The late great Grace Hopper used to hand out 30 cm (roughly 1 foot) lengths of wire as physical examples of a nanosecond: that's how far light can travel in one billionth of a second. If Google considers a 4 GB model to be "nano" sized, then it puts Hanff's hyperbolic comment about the climate footprint into real perspective. It gives a hint of the size of the real gigantic models in the datacenters metastasizing across the world. A recent study led by Grace Liu at Carnegie-Mellon found that regular AI use caused measurable cognitive impairment. It's worth thinking carefully about what we trade away when we outsource our thinking and, separately, what the planet pays to power the systems we're outsourcing it to. We suggest you turn it off now, everywhere you can. ®