AI Grammar Checker

Grammar checkers have a reputation problem, and it is deserved. The underline appears, you accept the suggestion, and the sentence becomes slightly wrong in a new way: a comma removed that was holding two clauses apart, "which" swapped for "that" in a clause where it did not matter, a passive sentence rewritten into an active one that now blames the wrong person. The problem is not that the tool is stupid. It is that a checker with no idea what you meant can only guess from the shape of the sentence.

A language model has a different advantage: it has read enough English to know which constructions usually carry which meaning. That does not make it an authority — it makes it a competent second reader who is occasionally confident and wrong. Used that way, it is genuinely useful.

The errors worth fixing first

In everyday writing, four categories cause almost all real damage. Agreement errors — "the list of items are long" — are unambiguous and should always be fixed. Then tense drift: a paragraph that begins in the past and quietly slides into the present, which readers experience as unreliability rather than as an error. Then punctuation that changes meaning: the difference between "Let's eat, grandma" and its grimmer cousin is a comma. Finally, the misplaced modifier — "walking to the shop, the rain started" — where the sentence claims something impossible.

Style is a separate category and should be treated as advice, not correction. Splitting a long sentence, removing a passive construction, cutting an adverb: each of those is sometimes right and sometimes exactly wrong. A passive sentence is the correct choice when the actor is unknown or unimportant, and "mistakes were made" is evasive for reasons that have nothing to do with grammar.

Why the page shows notes instead of a diff

A red-and-green diff looks authoritative but is hard to read on a phone, and it makes accepting the changes feel like a single decision. The corrected text sits at the top with a copy button, and the notes below name what changed in plain words: "subject and verb did not agree", "comma splice", "tense changed from past to present". Reading the reasons lets you disagree with one change without rejecting the rest.

Strictness, and when to turn it down

The three levels are not quality settings. "Only clear errors" leaves your phrasing alone and is what you want for an email to a client or a message in your own voice. "Errors and phrasing" is the everyday default for documents other people will read closely. "Also style" produces the most polished text and the least like you; use it for a landing page, not for a letter of complaint.

Whichever level you choose, read the result once at normal speed before copying. A correction that makes you stumble is a correction you should undo.

The limits, stated plainly

The model does not know your house style, your company's product names, or the inside joke in the third line. It will sometimes "correct" a deliberate fragment, a brand spelled with a lowercase letter, or a technical term that is not in its training data. It also cannot check facts: a sentence can be perfectly grammatical and completely false, and no checker will tell you.

So the right habit is small and constant: run the check, read the notes, accept what is clearly an error, reject anything that changes meaning, and keep a list of the corrections it gets wrong about your own writing. After two or three documents, that list becomes a style guide you wrote by disagreeing with a machine.

Read it out loud, once

The final check costs thirty seconds and catches what no checker can: a sentence that is correct and unreadable. Read the corrected text aloud at normal speed. Where you stumble, the problem is usually rhythm rather than grammar — three clauses of the same length, a verb pushed to the end, or a phrase that repeats a word from the line above. Fix those by hand; the checker will not suggest them, because nothing is technically wrong.

This is also the best way to notice a change that altered meaning. A sentence that once meant one thing and now means something slightly narrower will sound wrong when spoken, even if every word parses. The ear is a better editor than the underline, and it costs nothing.

One last rule: never accept a correction you cannot explain. If the note says “phrasing” and you cannot say what was clumsy, put the original back and move on. A document edited only where you understand the reason reads like you wrote it, which is the whole point of a second reader.