Quick Answer
The Grammar & Style Checker scans text for grammar, punctuation, clarity, and style problems — doubled words, its/it’s mix-ups, spacing slips, passive voice, wordy phrases, and long sentences — plus Flesch readability scores. Checking runs instantly as you type, entirely in your browser, with one-click fixes and a Fix-all per category. It is free, needs no account, and nothing you type leaves your device; the optional AI polish downloads its model once and then also runs locally.
How It Works
Paste or type text into the editor — the checker re-scans automatically about a quarter second after you stop typing
Read the results list: issues grouped by Grammar, Punctuation, Clarity, and Style, each with an excerpt and a plain explanation (the colour matches the annotated text)
Apply fixes with the per-issue Fix button or Fix all for a category; dismiss false positives with the × and they stay dismissed while the text is unchanged
Check the readability panel for Flesch Reading Ease, Flesch-Kincaid grade, passive-voice share, adverb density, and reading time
Optionally run the AI polish — a one-time ~300 MB model download that then runs offline in this browser and shows a read-only before/after comparison
Key Facts
- Instant checks as you type — deterministic rules, no waiting, no network calls
- 14 rule families across Grammar, Punctuation, Clarity, and Style
- One-click Fix per issue and Fix-all per category, applied to your text
- Dismissals are remembered per span, so a re-scan never resurrects them while the text is unchanged
- Inline annotated view — click a highlight to jump to its entry in the results list
- Flesch Reading Ease and Flesch-Kincaid grade with a vowel-group syllable counter
- Passive-voice share, adverbs per 100 words, and reading time at 200 words per minute
- Optional AI polish via flan-t5-base — a one-time ~300 MB download that then works offline
- Your text is saved automatically in this browser (localStorage) and never uploaded
Frequently Asked Questions
How does this grammar checker work?
It runs a deterministic rule engine in your browser: about fourteen rule families (doubled words, a/an agreement, its/it’s and your/you’re confusion, spacing, double punctuation, sentence capitalisation, terminal punctuation, repeated sentence starts, passive voice, adverbs, long sentences, wordy phrases, intensifiers, and clichés) each return exact text spans with an explanation and, where the correction is safe, a suggested replacement. Clicking Fix replaces that span in your text; Fix-all applies every fix in a category from right to left so offsets stay valid.
Is it free, and are there limits?
Yes — free, no account, no word limits. The engine is plain JavaScript over your text, so a 10,000-word document scans as easily as a sentence. The optional AI polish is the only part with a cost: a one-time model download.
Is my text private?
The rule checker makes zero network calls — nothing you type leaves your device, and your text is only saved to this browser’s localStorage. The optional AI polish downloads the flan-t5-base model file from a CDN once (about 300 MB); after that it also runs locally and works offline. That model download is the only network traffic the page can generate.
How is it different from Grammarly?
Grammarly is a cloud service: your text is sent to its servers for analysis, and its Premium tier costs about $12 per month billed annually per Grammarly’s published pricing (late 2026). This tool trades that depth for transparency and privacy — a fixed, inspectable rule set that runs offline in your browser, free, with readability stats included. It does not attempt to rewrite whole sentences (except in the clearly optional AI polish panel).
Why does it sometimes not flag its/it’s or your/you’re errors?
Deliberately. These words are only flagged when the surrounding pattern forces one reading — for example “its been” (been needs an auxiliary, so it must be “it’s”) or “it’s own” (own needs a possessive). Ambiguous cases like “its time” are left alone rather than guessed wrong.
What does the optional AI polish do?
It loads flan-t5-base, a small text-to-text model, via transformers.js and asks it to fix grammar and spelling while keeping the meaning, working through your text in chunks of at most 300 characters. The first use downloads about 300 MB of model files from a CDN (with a progress bar); the browser caches them, so later runs work offline. The result is shown read-only next to your original with a changed-word count and a copy button. If the download fails, the deterministic checker keeps working normally.