Grammar Checker

What is a grammar checker?

A grammar checker reads text and flags likely errors — subject-verb agreement, wrong tense, misplaced modifiers, punctuation, word choice — then proposes a fix. This one goes a step further: instead of just handing back a rewritten paragraph and leaving you to spot what moved, it returns the corrected text next to an itemised list of every change it made, each with the original wording, the replacement, and a short reason.

You can accept the changes you agree with and ignore the rest, because a correction you cannot see is a correction you cannot judge.

How to check your grammar

1. Paste or type your text. Drop up to 3,000 characters into the single text box; a live character count keeps you under the limit.
2. Press Check grammar. Nothing happens automatically as you type — each check is a real request to the model, so the button shows “Checking…” while it works.
3. Read the corrected text and the change list. Copy the corrected version with one click, then read the list of changes to see what it was before, what it is now, and why, before you decide what to keep.

What it catches and what it cannot

The AI checker catches real grammar problems: agreement errors, wrong verb forms, dangling modifiers, comma splices, missing or extra punctuation. But every fix a model makes is a judgement it made, not a certainty — it can “correct” language you wrote on purpose, like dialect, a sentence fragment used for effect, technical jargon, or an unusual proper noun, and it can just as easily miss a genuine error sitting in an otherwise clean sentence. That is exactly why the change list exists: read it rather than trusting the rewritten block wholesale, and reject any change that undoes something you meant.

It is also not a style guide. The serial comma, British versus American spelling, and how long your sentences run are choices, not errors, and this tool corrects the language you wrote in rather than pushing you toward a house style.

One more thing worth knowing: checking grammar with AI means your text leaves your browser and goes to a server to be processed by the model before the corrections come back. Most tools on this site never upload anything you type or drop in — this is one of the few that does, because correcting language genuinely needs a model to do it.

What the offline fallback actually checks

When the AI mode hits its rate limit or the site’s shared daily budget for model calls, the page does not stop working and it does not fake a grammar opinion. Instead it runs a mechanical check locally, in your browser, and shows you what it found. This is deliberately a much narrower thing than grammar checking: it only reports what can be proved from the characters themselves, with no view about meaning. Concretely, it looks for five things — a word repeated twice in a row, two spaces where one was intended, an unclosed bracket, an odd number of straight double quotation marks, and a space sitting before punctuation that should not have one.

Locale changes what counts as an issue, and this is where it got interesting. French typography genuinely requires a space before “;”, “:”, “!” and “?”, so that check is switched off entirely for French rather than reported as noise — flagging it would be a mistake, not merely a nuisance. Arabic uses its own comma, semicolon and question mark (، ؛ ؟), and those are what get checked there instead. Curly quotation marks are left alone on purpose too: a closing single quote and an apostrophe are the same character, so pairing them up would flag every “don’t” as unbalanced. Only straight double quotes are counted.

That mechanical check was tested against 38 assertions, including one that runs clean prose in all five of the site’s languages through it and requires zero false alarms, plus 4,000 random strings that must never crash it. A checker that fires on correct writing would be worse than no checker at all, so that is the property the tests are built around.

Why is it free?

The AI mode costs money every time it runs, so it is bounded rather than unlimited: 5 requests a minute, 30 an hour, 3,000 characters per request, and a daily budget shared across every AI tool on the site. Once that budget is spent, the mechanical fallback takes over — it runs entirely on your machine, so it costs nothing no matter how many times you use it.

Either way there is no account to create, no sign-up form, and no watermark on what you copy out. If what you actually want is text rewritten in a different voice rather than corrected in the one you used, that is a separate job — the paraphrasing tool does that instead.