Grammar checking that keeps your writing to yourself

CEO Owl checks English writing for spelling, agreement, punctuation and style problems. The editor runs entirely in your browser, so the text you check never leaves your device. Assistants such as Claude, ChatGPT and Cursor can connect to the same checker by signing in.

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Runs on your device

The editor loads the checker into your browser. Your writing is analysed locally and is never uploaded.

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Nothing is kept

No submitted text, no fragments, no suggestions and no corrected output are stored or logged — anywhere.

English only. This service checks English text. Requests in any other language are refused with a clear message rather than guessed at.

Privacy. We do not train anything on your writing, and we do not keep it. Only anonymous counts — how many checks ran, how long they took — are recorded. Read the privacy note.

Built on Harper. Grammar analysis is performed by the open-source Harper engine, licensed under Apache 2.0. This is an independent project and is not endorsed by or affiliated with Automattic. Full attribution.