Google Chrome has been quietly downloading a large AI model onto eligible devices. The browser does this without directly notifying users, according to a privacy researcher. Consequently, Google Chrome quietly downloading 4GB AI model stored inside a folder called OptGuideOnDeviceModel within the user data directory. Hanff discovered the behavior while conducting an automated audit on a fresh Chrome profile using macOS kernel filesystem logs. Chrome created a temporary directory, downloaded the AI model components, and stored the completed file on disk in about 15 minutes without any prompts or user interaction.

The same behavior reportedly occurred on Windows 11, Apple Silicon Macs, and Ubuntu systems. Users who previously noticed unexplained storage usage now appear to have identified the source. The model powers on device tools like email writing assistance, scam detection, smart paste, page summarization, and AI assisted tab grouping. On Windows systems, the file sits in the Chrome user data folder. Mac and Linux systems use equivalent profile directories.

Deleting the folder does not permanently remove the model. Chrome reportedly downloads it again after a restart unless users disable the feature. The report noted that Chrome’s AI Mode button in the address bar does not use the local model. Instead, AI Mode sends queries to Google’s cloud servers. Therefore, Google Chrome quietly downloading 4GB AI model that does not even handle those requests privately. Privacy researcher Hanff argued the behavior may violate EU privacy rules. Google acknowledged on its support pages that Chrome may download generative AI models in the background.