Private Writing AssistantWhat does “on-device AI” actually mean?
On-device AI means the AI model runs on your own computer or phone instead of on a company's servers. What you type is processed where you typed it, so it doesn't have to be sent anywhere, and the feature keeps working without an internet connection.
Cloud AI and on-device AI
Most AI features you've used are cloud AI. Your request travels to a data center, a large model works on it there, and the answer travels back. The model never leaves the company's computers; your input has to come to it.
On-device AI turns that around. The model is a file on your own disk. When a feature needs it, it is loaded into your computer's memory and runs on your processor or graphics card. Your input stays where it is; the model has come to you.
What it changes for you
- Privacy. Your input never leaves the device, so there is no copy elsewhere that could be stored, leaked or used for training.
- Offline use. Once the model is downloaded, the feature works without a connection: on a plane, on a train, on a network that blocks outside services.
- No account. There is no server that needs to know who you are or count your requests.
- Steady speed. Results don't depend on how good your connection is right now.
What it costs
A model that fits on a laptop is smaller than one in a data center. It is built for focused jobs, such as checking and rewriting text, rather than open-ended research or long essays. It also needs capable hardware, free disk space, and a one-time download of a few gigabytes before the first use.
That trade is worth it for some tasks and not for others. For text you'd rather not hand to anyone, a focused local model is often the better deal.
Chrome Built-in AI
Google Chrome now comes with on-device AI that websites and extensions can use, called Chrome Built-in AI. Chrome downloads the model once, then features that use it run it locally.
Its requirements come from Chrome: version 138 or newer on Windows, macOS, Linux or a Chromebook Plus, 22 GB of free disk space, and either a graphics card with more than 4 GB of memory or 16 GB of RAM. The model itself is a few gigabytes; the 22 GB is the room Chrome wants to keep free. Will it run on my computer? shows how to check each point.
How to tell whether a tool really runs on your device
- It keeps working with Wi-Fi switched off.
- Its privacy policy says where your input is processed, not just that it is “secure” or “encrypted”.
- It needs a model download, or a model your browser or operating system provides.
“Encrypted” only describes the trip to a server. It says nothing about what happens once the text arrives.
Where Private Writing Assistant fits
Private Writing Assistant is built on Chrome Built-in AI. Spelling and grammar checks and rewriting run on your computer, in 101 languages, and what you write on websites is never sent to us or to an AI service. How it works walks through what happens to your text, step by step.
Try on-device AI where you write every day: add Private Writing Assistant to Chrome. It's free and needs no account.
