PDF Page Compare Overlay
Choose two PDF pages independently and inspect their rendered overlap without uploading either file.
A QUICK WALKTHROUGH
How to use this tool
- Choose two valid, unencrypted PDFs and one page number from each.
- Set the second-page opacity and pixel tolerance, then render the overlay.
- Inspect the blended preview, changed-pixel estimate, dimensions, and alignment note.
Rendered visual overlay
The preview draws page A, blends page B at the selected opacity, then tints pixels red where any RGB channel differs by more than the tolerance. This can reveal visual movement, but anti-aliasing and renderer differences can also be marked.
Defined alignment and threshold
Pages are rendered at the same 1.5× target scale, capped at 2,000 pixels on the longest side, then aligned at their top-left corners. Pixels outside the smaller rendered page count as a size difference. The adjustable RGB channel tolerance is 0–64.
Local limits
Each PDF is limited to 50 MB and 100 pages. Only one page pair is held for comparison, each side is capped at 2,000 pixels, and combined working buffers are capped at 192 MB.
GOOD TO KNOW
Common questions
Does this compare PDF text or meaning?
No. It compares the pixels produced by browser PDF rendering; text, structure, metadata and meaning are not compared.
Can I choose different page numbers?
Yes. Choose one page from each PDF independently.