AI Grammar Checker is a free and open-source Chrome extension that provides smart grammar checking directly in your browser. It analyzes full sentences rather than just individual words, offering more accurate corrections. The extension runs AI locally on your machine, ensuring your data never leaves your device. By default, it uses Chrome’s built-in Gemini Nano (version 138+), but you can switch to a local Llama server. No subscriptions, no ads, and no data collection make it a privacy-friendly choice for.