Compare PDF
Choose the original and the revised PDF. The tool extracts the text of both and shows every line that was added or removed.
Choose two PDFs to compare their text.
About this tool
When a counterparty sends back a “slightly updated” contract, reading it again from the first page is slow and risky. A text comparison lists exactly which lines changed. The tool extracts the text layer of each document with pdf.js, normalises whitespace, and runs a longest-common-subsequence diff on the lines, the same algorithm behind code review tools.
Lines in green exist only in the revised file, lines in red only in the original, grey lines are unchanged. Layout, fonts and images are not compared; scanned PDFs without a text layer need OCR first (use Image to Text).
Frequently asked questions
- Both files look the same but changes are listed — why?
- Reflowed text, different page breaks or hyphenation can shift lines. The comparison ignores blank lines and surrounding spaces but not words split differently.
- Can I compare scanned documents?
- Only if they contain a text layer. Run OCR on them first.
- Is the comparison done on a server?
- No. Text extraction and the diff both run in your browser; the files are never uploaded.