Drop in two versions of a document and see exactly where they differ — each changed page rendered with the differences highlighted in red, on your device.
A counterparty returns the contract with "just the date updated". A landlord sends a "corrected" lease. A supplier reissues a quote. Reading forty pages side by side to confirm nothing else moved is exactly the kind of work humans do badly — a changed digit in a payment clause is invisible at reading speed. A visual comparison does it mechanically: every page pair is checked pixel by pixel, and anything that moved, appeared, or vanished lights up.
Both documents are rendered page by page with pdf.js — the engine Firefox uses to display PDFs — at matching resolution, and corresponding pages are compared pixel by pixel. The result for each changed page is a picture: the page in faded gray with every difference in red, plus a percentage of how much changed. Unchanged pages are listed but not cluttered with images; pages that exist in only one document are flagged. The full set of diff images downloads as a ZIP for records or review notes.
Because the comparison is visual, it catches everything that affects the rendered page — edited text, moved paragraphs, swapped images, added stamps — and it works on scans, which text-based diff tools can't read at all. The flip side: a purely cosmetic reflow (say, a font substitution shifting every line) also lights up, because visually it IS a change.
Comparing contracts means handling two confidential documents at once — double the reason not to send them anywhere. Both files are rendered and diffed by code running in your browser; nothing is transmitted, no account is required, and there's no page-count paywall. Documents up to 60 pages compare comfortably; split longer ones and compare in parts.
No. Both PDFs are rendered and diffed entirely in your browser — neither version ever crosses the network.
Yes — the comparison is visual, so scans compare as well as digital PDFs. That's something text-based diff tools can't do, since scans have no text layer.
It shows where changes are — highlighted in red on each page — rather than a word-by-word edit list. For contract review, spotting the changed clause is usually the hard part; reading it is quick.
The revised version probably reflowed — a font change or layout shift moves every line, which is honestly reported as a visual change even if the words are identical.
Extra pages are flagged as existing in only one document, and the summary shows both page counts side by side.