Compare PDFs
Upload two PDF files and instantly see what changed — view them side by side, overlaid, or as a pixel-level difference map. Your files never leave your device.
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Frequently Asked Questions
- Is PDF Compare free?
- Yes, 100% free. No account, no limits, no watermarks.
- Are my PDF files safe?
- All processing runs entirely in your browser using JavaScript. Nothing is uploaded to any server — your files stay on your device.
- What do the three view modes do?
- Side by Side renders both PDFs next to each other for easy visual comparison. Overlay superimposes them with an adjustable opacity slider so you can blend between the two. Difference highlights every changed pixel in red on a grey background, making edits immediately obvious.
- How accurate is the pixel difference?
- The diff compares every pixel of the rendered pages. Small rendering differences (anti-aliasing, sub-pixel shifts) use a tolerance threshold to avoid false positives, so only meaningful changes are highlighted.
- Can I compare multi-page PDFs?
- Yes. Use the Previous / Next page buttons to compare each page pair. Both PDFs are navigated simultaneously.
- Does it work on mobile?
- Yes, works on all modern browsers including mobile Safari and Chrome on Android.