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Compare Two PDFs

Upload two versions of a PDF and instantly see every word that was added or removed.

Your files never leave your device. DocZap processes everything locally in your browser.

Original PDF

Drop a PDF here or click to browse

Your file is processed locally — nothing is uploaded

Modified PDF

Drop a PDF here or click to browse

Your file is processed locally — nothing is uploaded

Three steps

How to use the Compare PDF tool

  1. 01

    Upload both PDFs

    Drop in the original version and the modified version you want to check.

  2. 02

    DocZap compares the text

    Every word is checked against the other document, entirely in your browser.

  3. 03

    Review the differences

    Additions appear in green, removals in red, so you can scan changes at a glance.

Find out what actually changed between two PDFs

Contracts get redlined, reports get revised, and forms get resubmitted — and it's rarely obvious what actually changed between one PDF and the next just by eyeballing them side by side. DocZap's Compare PDF tool reads the text from both files and highlights every addition and removal, so you can review a revision in seconds instead of re-reading the whole document.

Built for content changes, not pixel differences

This tool compares the actual text inside each PDF rather than the rendered appearance of the page, which makes it well suited to catching the changes that matter most — an edited clause in a contract, a changed number in a report, a deleted paragraph in a policy document. It's not designed to flag purely visual differences like a shifted logo or a different font.

Everything happens in your browser tab

Both files are read using pdf.js, and the comparison itself runs with a JavaScript diff algorithm, all locally on your device. Neither PDF is ever uploaded anywhere, which matters given how often the documents worth comparing — contracts, financial statements, legal filings — are exactly the kind you don't want passing through an unfamiliar server.

Once you've reviewed the differences, DocZap's Redact PDF or Watermark PDF tools below are useful next steps before sharing the finished document.

FAQ

Frequently asked questions

How does DocZap compare two PDFs?+

DocZap extracts the text content from both PDFs using pdf.js, then runs a word-by-word comparison entirely in your browser. Added text is highlighted in green, removed text is shown struck through in red.

Does it compare formatting or images, or just text?+

Just text. DocZap compares the words in each document, so it's built for catching content changes — added clauses, edited numbers, deleted paragraphs — not visual layout differences like moved images or changed fonts.

What if the two PDFs have a different number of pages?+

That's fine. DocZap joins all the text from each document before comparing, so it still finds matching and differing sections even if pages were added, removed, or reordered.

Are my files uploaded to compare them?+

No. Both PDFs are read and compared entirely inside your browser using pdf.js and a JavaScript diff algorithm. Neither file is ever sent anywhere.

Can I save the comparison result?+

Yes. After comparing, you can download a plain-text report listing every addition and removal, alongside the full word count summary.

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