Does it work on scanned PDFs?

No — diff is text-level. Run scans through OCR PDF first.

How are pages paired?

Page 1 of A vs page 1 of B, page 2 vs page 2, etc. If the documents are differently paginated, the diff will be noisy. Use Merge / Split first to align them if needed.

Are the files uploaded?

No — text extraction runs locally via pdfjs, diff and rendering via pdf-lib. Nothing leaves your browser.

Redline Comparison (Track-Changes Style)

Compare two PDFs and produce an inline-redline report — deleted text struck through in red, inserted text underlined in green.

Your files never leave your browser. All processing happens on your device — nothing is uploaded.

1. Upload your files (min 2)

Need at least 2 files (have 0).

How does the Redline Comparison (Track-Changes Style) work?

Compare two PDFs and produce a clean redline report in classic legal track-changes form: removed text drawn in red with a strikethrough line, newly-inserted text drawn in green with an underline. Files are paired alphabetically by name (so name them sensibly — "v1-old.pdf" and "v2-new.pdf"), then diffed page-by-page using a line-level alignment. The output is a single PDF with a cover summary plus one page per page-of-comparison. Use Compare Two PDFs (the existing tool) if you want a side-by-side per-page split instead of inline redline.

🔒 Security & Privacy

All processing happens on your device. Your files never leave your browser, never touch our servers, and are not stored anywhere. Close the tab and the file is gone.

📱 Use it on any device

Works in any modern browser — Mac, Windows, Linux, iPhone, Android, and tablets. No installation, no app to download. Just open the page and start.

⚡ Quick & easy

Drag, drop, click. Most files process in seconds, not minutes. No watermarks added to your output, no per-day limits, and the tool always shows the result before asking you to download.

🎁 Always free, no signup

Free to use, every time. No account creation, no email required, no “trial” that converts to a paid plan. We make money from ads so you don’t have to pay.

Frequently asked

Compare Two PDFs gives you a per-page diff report; Redline Comparison gives you the classic legal inline format (strike-through removed, underline inserted). Pick whichever style your audience expects.