Compare PDF · 2 min read

How to Find Differences Between Two PDF Files — Instantly

Finding differences between two versions of a PDF manually is slow and error-prone. This tool does it automatically — scanning every pixel on every page and highlighting exactly what changed.

1

Step 1 — Upload the Two PDF Files

Open pdfeditor.onl/compare-pdf. Drag File A (the original) and File B (the updated version) into their respective upload zones.

2

Step 2 — Click Compare to Find All Differences

Click Compare. The engine renders both documents and performs a pixel-level diff on every page pair. Results appear within seconds for most documents.

Tip: The summary panel shows at a glance: how many pages are identical, how many changed, and the average percentage of change across all pages.

3

Step 3 — Inspect the Highlighted Differences

Switch to Diff view to see each page as a greyscale image with red highlights marking every changed pixel. Switch to Side by Side for a direct visual comparison. Use Overlay to drag between both versions on the same canvas.

Find PDF Differences — Free →

Frequently Asked Questions

Does it work if the PDFs have different fonts or layouts?

Yes. Since the comparison is pixel-based, it detects any visual difference regardless of whether it is a font change, a layout shift, an image swap, or a text edit.

Can I find differences in just one specific page?

Yes. Navigate to the page using the page strip and the diff result for that specific page is shown. You do not need to scroll through the entire document.

Is this free?

Yes — 100% free, no account, no file size limits beyond your device RAM.

← Back to All Guides