Upload two PDFs — an original and a modified version — and see every text change highlighted side by side, page by page. Everything runs in your browser; your files are never uploaded anywhere.
Yes, 100% free with no limits on file size within reason (up to 50 MB per file) and no signup required.
No. Both files are read and compared entirely inside your browser using the pdf.js library. Your documents never leave your device.
The text of each page is extracted from both PDFs and matched page by page. A line-level diff algorithm then aligns the two versions: lines only in the modified file are highlighted green, lines missing from it are highlighted red. Pages that exist in only one file are shown as fully added or removed.
Scanned or image-only PDFs have no text layer — they’re just pictures of pages — so there is nothing to extract or diff. This tool doesn’t do OCR. If you need to compare scanned documents, run them through an OCR tool first, then compare the resulting PDFs here.