How to compare PDF documents
Upload your original and revised PDF — or a Word, PowerPoint or OpenDocument file, which is converted to PDF first. Every changed word is highlighted directly on the page, with a minimap and a Changes panel for jumping between them.
PDFs are read entirely in your browser — nothing is uploaded, and the comparison runs on the words pdf.js extracts, so it stays accurate on long documents.
Are my files uploaded anywhere? — PDFs are not — they are parsed, rendered and compared entirely in your browser. Word, PowerPoint and OpenDocument files are the exception: converting one to PDF needs a layout engine no browser has, so that file is sent to our conversion service and deleted as soon as the PDF comes back. The comparison itself always runs locally.
Does it work on scanned PDFs? — Yes. A scan has no selectable text, so the tool offers to read the pages with OCR rather than reporting no changes; once it has, the scan compares, highlights and exports like any other document, and its text is selectable on the page.
Does formatting count as a change? — No — the comparison is on the text itself, so a font or colour change alone is not reported.