Compare PDF
Received a “final” version of a contract or a quote? Drop the old and the new PDF to see exactly which lines were added, removed or changed — without reading both side by side.
Runs in your browser
How to use
- Drop the original PDF on the left.
- Drop the changed PDF on the right.
- Click Compare PDFs.
- Review the highlighted lines; tick or untick “Only show changes”.
How it works
Both files are read with Mozilla's pdf.js, the engine of Firefox's PDF viewer, which extracts their text page by page. The two texts are then compared line by line with a longest-common-subsequence algorithm: green lines were added, red lines were removed, and unchanged lines are hidden around each change unless you ask to see everything.
It compares words, not appearance: a changed font, colour, image or layout is not reported. Scanned PDFs have no text layer, so there is nothing to compare — the tool tells you when that is the case.
Both documents are processed in your browser and never uploaded.
Examples
- Contract revision
- v1 vs v2 of a lease → the deposit line changed from 1,200 to 1,500 and one clause was added.
- Quote update
- Spot a removed line item before you sign the new quote.
Common uses
- Checking contract and quote revisions
- Reviewing edited reports and theses
- Verifying that a re-exported PDF kept its text
Privacy & security
This tool runs entirely in your browser. Your files and text are never uploaded to our servers — processing happens on your device and results are created locally. How each tool handles files
Frequently asked questions
Does it compare images and layout?
No. It compares the text only. A visual, pixel-by-pixel comparison is a different tool we have not built yet.
My PDFs are scans — why is nothing found?
Scans are pictures of text, with no text layer to read. They would need OCR first, which isn't available here yet.
Are the files uploaded?
No. Both PDFs are read and compared in your browser.
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