thatbeautifuldream/ondevice-ai

This project is a private chat application that runs entirely on your own computer through Chrome's built in Gemini Nano model, rather than sending your messages to a server. Because the AI model itself ships inside the browser, every question and answer stays on your device, with no API key to set up and no external service involved. Beyond the basic chat page, the project includes a few extra playgrounds that show off different parts of Chrome's built in AI features. One page demonstrates structured output, where you can give the model a JSON schema and it is forced to reply with valid, parseable data instead of free form text, and it lets you compare that constrained answer side by side with a normal unconstrained one. Another page is a translation tool that automatically detects what language you are typing in and then streams a translation, downloading each language pair only when needed so it can keep working offline afterward. A third page brings together three writing assistance tools built into Chrome: one that drafts new text from a prompt with tone and length options, one that rewrites existing text to be more formal, more casual, shorter, or longer, and one that proofreads for grammar and spelling and shows each correction inline. The chat page itself keeps track of conversation history in the browser's local storage, streams responses formatted as Markdown, and automatically summarizes older parts of a long conversation on device when the context window starts filling up. To use this project you need a fairly recent version of Chrome with a few experimental flags turned on so the Gemini Nano model can download and run locally, and the app walks you through enabling them if it detects the model is missing. It is built with Astro, React, and Tailwind CSS. This is a small demo project aimed at developers curious about on device AI in the browser, currently with no stars.