Detect tower · floor
Grammar checker: what it sees, what it fixes
A grammar checker is the most widely installed writing tool in the world, and almost nobody installs it as a program. It arrives as a browser extension, and that single fact is the most important thing on this floor.
An extension that corrects your writing wherever you write has to be able to read wherever you write. That is not a flaw or a scandal — it is what the feature requires. But it is worth seeing stated plainly, by the companies themselves.
From the privacy policy covering LanguageTool, read 21 August 2026. It is quoted here not as an
accusation but as a description: this is what a browser extension that checks your writing
everywhere has to be able to do. The permission is the product.What a grammar-checking extension can see
“Content we collect also includes information about your browsing session and the
content of websites visited when using our browser extensions… this may include the content and
metadata of all websites you’re visiting during your active browser session (e.g. website text,
media, publisher and author names, URLs).”
LanguageTool’s privacy policy is issued by Learneo, Inc. — the same business behind QuillBot,
whose product menu carries a paraphraser, an AI detector and an AI humaniser. Read on their own
sites on 21 August 2026. Worth knowing before treating any two of those tools as independent
second opinions.Two of the biggest names here belong to the same company
The searches split by how far along somebody is. Grammar check and english grammar check are people who want a sentence looked at once. A grammar checker or a free grammar checker is somebody choosing a tool to keep. Grammarly is the name that has become the category, and a punctuation checker is the narrowest and most answerable request of the lot.
With that established, the rest of the floor is the ordinary question: what these tools actually catch, what they miss, where the free versions stop, and the point at which a checker stops improving your writing and starts sanding it down.
Where to start
Five ways in.
- “Which one should I install?”
- Start at what they catch
- “Is the free version enough?”
- Almost always — free and paid
- “I do not want an extension reading everything.”
- Go to without an extension
- “My writing sounds flat after I accept the suggestions.”
- That is when to ignore it
- “English is not my first language.”
- Read what they catch
What they catch
Three different jobs sold under one name: mechanical correctness, clarity, and style. Only the first has right answers.
Free and paid
The honest arithmetic. For most writing the free tier is not a stripped demo — it is the part that does the work.
Without an extension
For confidential work, client documents or anybody who would rather not grant a browser-wide permission. All of these routes exist and most people never hear about them.
When to ignore it
The wing that keeps your writing yours. A checker optimises for a general reader, and you are usually writing for a specific one.
What this tower will not do
It will not tell you to install an extension without saying what it can see. The quotation at the top is from the company’s own policy, and anybody choosing one of these tools deserves to read it before the install button, not after.
It will not rank the checkers yet. That needs the same set of real documents run through each of them over weeks, with the misses and the false corrections counted — which is a test, and it is the only thing worth publishing here.
And it will not treat a suggestion as a correction. A great deal of what these tools flag is preference rather than error, and a writer who accepts everything ends up sounding like every other writer who accepted everything.
One closing note on how this floor was researched, since it is the reason it says what it says. The quotation at the top was not taken from a review or a summary; the policy pages of these companies block automated reading, so they were opened in an ordinary browser and read the way a customer would read them. That is also how the second observation surfaced — that two of the largest names in this tower share a parent company. Neither fact is hidden, and neither one appears in the comparison articles that rank above this page. What holds instead is simple: the policy quotations here were read on the companies’ own sites, with the date.
Where this page got its facts
- The privacy policy covering LanguageTool, issued by Learneo, Inc. — what is collected from browser extensions and from content you provide — languagetool.org, read 21 August 2026.
- QuillBot’s product menu, listing a paraphraser, an AI detector and an AI humaniser under the same company — quillbot.com, read 21 August 2026.
Written by Alberto Gulotta
Founder and editor of AI Tools Primer, writing from Palermo, Italy. Thirty-five years of taking computers apart, starting with a Commodore 64 — the long version is on the about page.
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