Compare PDF Files Online Free

Upload two PDFs and instantly see visual differences highlighted page by page.

File A (Original)

Drop files here or click to upload

Max 100 MB

File B (Modified)

Drop files here or click to upload

Max 100 MB

Compare two PDF files online free and see exactly what changed. This tool renders each page as an image and highlights pixel-level differences, all processed locally in your browser.

Last reviewed: July 2026

How to use this tool

  1. 1Upload the original PDF file (File A).
  2. 2Upload the modified PDF file (File B).
  3. 3Click Compare to render and analyze differences page by page.
  4. 4Review the side-by-side comparison and download the diff report PDF.

Common use cases

  • Verify contract revisions by comparing the original and updated versions.
  • Check design proofs to catch unintended layout changes between PDF exports.
  • Validate document translations by comparing source and translated PDFs side by side.

Technical notes

  • Pages are rendered at 1.5x scale for clear comparison while managing memory.
  • Pixel differences above the threshold are marked with a red overlay.
  • Pages with different dimensions are aligned center and size mismatches are flagged.

Private by design

This tool runs in your browser. Your file is not uploaded to our server while using the tool.

Limitations

  • Maximum recommended file size is 50 pages per PDF for smooth browser performance.
  • Color-shift differences below the sensitivity threshold may not be detected.
  • This is a visual comparison tool — it does not extract or compare text content.

Frequently Asked Questions

How does the PDF comparison work?

Each page of both PDFs is rendered as an image, then pixels are compared. Differences above a threshold are highlighted in red.

Can I compare PDFs with different page counts?

Yes. Pages are compared in order. Extra pages in either file are marked as added or removed.

Is there a page limit?

We recommend 50 pages or fewer per file for smooth performance. Larger files depend on your browser memory.

Can I download the comparison result?

Yes. You can download a PDF with difference overlays or view the side-by-side comparison in your browser.

Are my files uploaded to a server?

No. Both PDFs are processed entirely in your browser using a Web Worker.

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