How to Compare Two PDF Files (Side by Side)

Reviewing the second draft of a contract? You don't want to read the whole thing again. You want to see exactly what changed.

How a PDF diff works

A PDF comparison tool extracts the text from both files, aligns paragraphs, and highlights additions, deletions and changes. Some tools also do a visual pixel-level diff to catch layout shifts.

Compare two PDFs online

1. Open Compare PDFs.
2. Upload the original and the new version.
3. Review the highlighted changes side by side.

What to watch out for

• Page order changes can confuse text alignment — re-order pages with Reorder Pages first if needed.
• Scanned PDFs need to be OCR'd before they can be diffed at the text level. Use OCR PDF.
• Image-only changes won't show in a text diff — switch to visual mode.

Use cases

• Contract revisions.
• Policy updates.
• Spec sheet changes between product releases.
• Comparing your draft against a published version.