What this tool does
- Word-level text diff — additions and deletions highlighted inline, page by page
- Visual overlay — renders both pages and highlights the pixels that moved, for scans and layout changes
- Side-by-side view — scroll both documents together
- Change summary — a per-page count of what was added and removed, so you know where to look
Text diff or visual diff?
Use the text comparison when both files have a real text layer — contracts, reports, anything exported from a word processor. It extracts the words from each page and runs a longest-common-subsequence diff, so a single changed figure in a long clause shows up precisely rather than flagging the whole paragraph.
Use the visual comparison for scans, signed documents, drawings or anything where layout matters as much as wording. Both pages are rendered to the same size and differing regions are tinted, which catches a moved logo or a changed figure in a chart — things a text diff cannot see.
Why compare PDFs
- Check what a counterparty actually changed in the contract they sent back
- Confirm a supplier's revised quote only moved the price you negotiated
- Verify a re-exported report against the version you already signed off
- Find the difference between two near-identical invoices
Frequently asked questions
Are my PDFs uploaded anywhere?
No — the file is opened and rewritten entirely inside your browser using JavaScript. Nothing is uploaded to a server, so your document never leaves your device.
What if the two files have different page counts?
Pages are compared in order, and any pages beyond the shorter document are reported as added or removed in full.
Why does the text diff show nothing on a scanned PDF?
A scan is an image with no text layer, so there are no words to compare. Switch to the visual comparison, or run OCR PDF on both files first.
How sensitive is the visual comparison?
There is a tolerance slider. Raise it to ignore minor rendering and anti-aliasing noise; lower it to catch a one-pixel shift.
Can I export the comparison?
You can print the results view to PDF with your browser's print dialog, which keeps the highlighting.