Instant, privacy-first grammar correction with plain-English explanations. Check English with the full AI model, or Spanish / Portuguese / Indonesian with our rule-based fallback — everything runs locally in your browser.
This AI tool runs entirely in your browser. Your text is not uploaded to any server.
Runs entirely in your browser. Your data never leaves your device.
For English text, we run a small but capable text2text-generation Transformer model directly in your browser via WebAssembly. The model takes your raw sentence and produces a corrected rewrite. We then diff the input and output to surface exactly which tokens changed — and generate a plain-English explanation for each change.
| Stage | What happens |
|---|---|
| Input tokenization | Your text is split into subword tokens by the model's tokenizer. |
| Correction inference | The WASM-accelerated model generates a grammatically clean rewrite. |
| Diff + explanation | We compute an edit script between input and output, then classify each change into a human-readable category (subject-verb agreement, article usage, etc.). |
| Render | Highlights are overlaid on the original, and each correction is paired with its explanation. |
The AI model is trained on diverse English writing and performs well for common learner mistakes — article usage, subject-verb agreement, tense shifts, and preposition errors. It may occasionally flag stylistic choices (e.g., "colour" vs "color") as errors. We recommend treating suggestions as guidance, not strict rules.
English is supported by the full text2text AI model. Spanish, Portuguese, and Indonesian use a lightweight rule-based fallback that catches common spelling and punctuation patterns. Additional languages may be added as compatible models become available for browser-side inference.
Mistakes are learning opportunities. Every correction includes a plain-English reason so you understand the underlying rule — like subject-verb agreement or article count — instead of just seeing a changed word. This helps you improve faster than a black-box checker.
Yes, after the first load. The model downloads to your browser cache on first use (approximately 30–60 MB) and all subsequent checks run fully offline. You can verify this by enabling Airplane Mode — the checker still works without internet.
We ran the rule-based checker against these representative sentences:
| Input sentence | Expected correction | Rule applied |
|---|---|---|
| he go to school every day | He go to school every day. | Capitalize first letter ("he" → "He") |
| i have many informations about this topic | I have much information about this topic. | Capital I + uncountable noun (many → much, informations → information) |
| she didnt went to the party | She didn't went to the party. | Missing apostrophe (didnt → didn't) + capital S |
| on weekend i like to reading a book | On weekend I like to reading a book. | Capitalize sentence + capital I |
| your welcome! its a beautiful day | You're welcome! It's a beautiful day. | your → you're + capital I + capital after period |
| i saw an uniform yesterday | I saw a uniform yesterday. | an uniform → a uniform |
All test cases matched expected rules. Last verified: September 2026.