Compare Two PDFs Visually, Page by Page
Compare two PDFs as rendered page images with side-by-side, overlay and pixel-difference views. This visual check does not compare text or file structure.
Document A
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Document B
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How to Compare Two PDFs
- Select both PDF documents; processing stays in your browser.
- Click Compare PDFs to start the visual comparison.
- Switch between Side by Side, Overlay, and Differences views.
FAQ
How does the comparison work?
Each page is rendered at 1.5× and page N is compared with page N. A pixel is marked when |R1−R2| + |G1−G2| + |B1−B2| > 30. The percentage is rounded to 2 decimals and is at least 0.01% when any pixel is marked.
Can I compare PDFs with different page counts?
Yes. Pages are compared in order. Extra pages in the longer document are shown as 100% different.
What do the view modes show?
Side by Side shows both pages, Overlay blends them, and Differences marks in red the rendered pixels that exceeded the threshold.
Can I compare text content instead of pixels?
No. PDFGem does not compare text strings, meaning, metadata, signatures or internal PDF structure. It compares rendered page images only, so review marked pages yourself.
Is there a page or file size limit?
Each file can be up to 100 MB. Very large documents may take longer to render and compare.