The error this catches
Quotations drift. Someone reads a passage, writes the sentence a day later from a note rather than the page, and reproduces the sense while losing a word — an although becomes a though, a hedge disappears, a plural turns singular. Nobody intended anything by it, and the quotation marks are still making a claim about exact wording that the sentence no longer supports.
The tool shows you the divergence rather than only reporting it. When a quote stops matching, the source text from that point onward appears underneath, which is usually enough to see what happened and fix it in a few seconds.
Why quotation accuracy is worth a tool of its own
Misquotation sits in an awkward gap. It is not plagiarism — the source is credited — and it is rarely deliberate, so it is not academic misconduct in the way fabrication is. It still undermines the thing a citation exists to do, which is let a reader go and check. A reader who follows your reference and finds different words has no way to tell a slip from a distortion.
It is also invisible to the checks people usually run. A similarity score rewards quoted text for matching a source and says nothing about whether it matches accurately, and an AI-writing score is not looking at quotations at all.
What this does not do
It reads nothing off the internet. There is no lookup, no database of sources, and no check that the work you pasted exists — everything happens in your browser against the text you supply, which is also why nothing you paste goes anywhere. If you need to compare two whole drafts rather than check quotations inside one, the diff checker is the tool for that. If the question is whether you can show you wrote something, the evidence that actually helps is drafting history rather than anything a text tool can produce after the fact.