Compare two PDF documents
Two versions of a contract, a drawing or a report: see exactly what changed, both as a highlighted difference map and as a text diff.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
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How it works
- Drop the original and the version you want to check.
- Choose visual, text or both, and how strict the pixel comparison should be.
- Compare — each page reports the percentage of pixels that differ, with a downloadable difference map.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see are the tool’s own code and, once cached, none at all.
Frequently asked questions
Why do the two comparisons disagree sometimes?
Because they measure different things. A font substitution or a re-export shifts pixels everywhere while the words are identical; conversely, a swapped digit is one changed word and a barely visible pixel change. Read them together — that is why both are shown.
What does the sensitivity slider do?
It sets how different two pixels must be before they count. Below about 0.05 you start catching anti-aliasing noise from the renderer itself; 0.10 is a good default for comparing real documents.
Can it compare scans with no text layer?
The visual comparison works on anything, since both files are rendered to images first. The text comparison needs an extractable text layer, and says so when there is none — run the OCR tool first if you need the words compared.
Are the documents uploaded?
No. Both are rendered by pdf.js inside this tab and compared here. Comparing two drafts of a contract on someone else’s server means handing over both drafts.