Grammar Checker
Fix grammar and spelling errors with AI, and see every change
About Grammar Checker
Grammar Checker corrects spelling, grammar, agreement, and clearly wrong punctuation with minimal edits, using OpenAI's GPT-4o mini. The model is told not to rewrite, rephrase, or translate, and to leave correct sentences exactly as written. The result is shown word by word in your text, removed words struck through in red and added words underlined in green, and each change can be undone. The text you copy or download as corrected.txt contains only the changes you kept. Your text goes through our server to OpenAI, up to 8,000 characters per request.
How to fix grammar and spelling
- 1Paste your text into the "Paste text to fix grammar…" box.
- 2Click "Fix grammar".
- 3Review each change in place, and click one to undo it (click again to restore it).
- 4Use "Keep all" or "Undo all" to decide in one step.
- 5Click "Copy" or "Download" to get corrected.txt with the changes you kept.
Formats and limits
- Input
- Text to proofread, up to 8,000 characters
- Corrections
- Spelling, grammar, agreement, verb forms, wrong or missing words, and clearly wrong punctuation; no style or word-choice changes
- Output
- Your text with the changes you kept, to copy or download as a .txt file
- Languages
- Tested on English and ten other languages; a notice appears for Japanese, Chinese, Russian, Hindi, and Turkish, where corrections were less reliable
- Usage limits
- Per-connection hourly and daily limits, shared with the site's other tools that rely on a paid service, and a monthly budget for the whole site
Where your text is processed
Your text is sent to our server and then to OpenAI's GPT-4o mini, which returns a corrected copy. Only the correction request goes to our server: the comparison that marks each change runs in your browser, and undoing or restoring a change sends nothing more. We do not store your text.
Frequently asked questions
Will it rewrite my sentences?
No. The model is told to make minimal edits, not to paraphrase, reorder, or change style, and to leave correct sentences as written. If it still changes something you wanted to keep, click that change to undo it.
Can I see what was changed?
Yes. Every change appears in place, removed words struck through and added words underlined, with a count of changes kept and undone. Undoing all of them gives back your original text exactly.
How well does it work in English?
25 of 25 typical errors were corrected in our English test of September 28, 2026, and a text without errors came back unchanged. It is a small test, so keep reviewing each change before you copy the result.
How reliable is it in other languages?
29 of 40 learner sentences were corrected exactly in Portuguese and 16 to 17 in German, but 11 in Spanish, 9 in Italian, and 6 in Arabic. Japanese, Chinese, Russian, Hindi, and Turkish texts get a notice on the page that corrections are less reliable.
Tips and tricks
- ✓Undo any change the tool made to a name, a brand, or a technical term it did not recognize.
- ✓If you want new wording rather than corrections, use AI Paraphraser instead.