Compare PDF

What this tool does

This tool renders matching pages from two PDF files and compares them pixel by pixel to estimate how different each page is, after first checking whether the two files have the same page count and page dimensions. For pages that share the same size, it highlights the differing pixels in a preview image so you can see at a glance what changed. It is intended for spotting edits between two versions of the same document, not for a byte-level or legally exact comparison.

How to use it

1. Choose the first PDF and the second PDF you want to compare.
2. Press Compare PDFs to see page counts, size differences and a pixel-difference percentage for each page.
3. Pick a page from the preview list to see a highlighted visual diff.

Privacy

This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.

Frequently asked questions

Are my PDFs uploaded to compare them?

No. Both files are rendered and compared entirely in your browser.

What does the difference percentage mean?

It is the share of pixels on a rendered page that differ noticeably between the two files, at a fixed comparison resolution. Small percentages can still be a real change, such as a single line of edited text.

What happens if the two PDFs have a different number of pages, or different page sizes?

Page counts are always shown. Pixel comparison only runs for pages present in both files; pages whose dimensions differ are reported as a size difference instead of a percentage, since they cannot be compared pixel for pixel.