Sidecar Grammar

Private, on-device grammar checking. Your writing is never transmitted — checked entirely on your device.

Sidecar Grammar checks your writing as you type — privately, and entirely on your own device. Your text is never sent to a server and never leaves your browser. All grammar and spelling checking runs locally using the open-source Harper engine, compiled to run right inside Chrome. No account, no sign-in, no tracking, no analytics. HOW IT WORKS Turn it on with one click. Sidecar Grammar underlines likely spelling and grammar issues in text fields as you write. Hover an underline to see the suggestion, click to apply it. It's a lighter touch than most checkers — it flags the specific words that need attention rather than rewriting your sentences for you. WHERE IT WORKS Standard text boxes and text areas across the web, plus Gmail compose. You control it per site: a master on/off switch, and a "this site" toggle so you can turn it off anywhere you don't want it. Some rich text editors aren't supported — if a field isn't being checked, open the extension and it will tell you. PRIVATE BY DESIGN - Your writing runs 100% on your device — nothing you type is ever uploaded - No account, no sign-in, no tracking, no analytics - Site access is only requested after you click Enable - Your settings stay in your browser ON UNINSTALL If you remove the extension, Chrome opens a short feedback page. It receives the extension version, how many days it was installed, and whether you ever applied a correction — no identifier, no account, and nothing you ever typed. The form itself is optional and asks for no personal details. Powered by the open-source Harper grammar engine (github.com/Automattic/harper).