siutil. PDF Compare
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Compare PDF Files Online

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Page comparison results

Red marks show visual differences at the rendered resolution. Scans, font substitution and shifted layouts can produce differences. Inserted pages: choose the matching page on each side. No text interpretation or automatic alignment. Up to 200 pages per file; passwords are not supported.

Compare before and after PDFs page by page in your browser. Highlight visible changes, overlay pages or view them side by side with linked zoom and scrolling. Choose matching pages manually after an insertion, then save the selected difference as a PNG. Free and local: document contents never leave your device.

How to use

  1. Choose the before and after PDF, or try the clearly labelled sample pair.
  2. Compare all page numbers to find changes, or select a page on each side. Correct the pairing manually if pages were inserted or removed.
  3. Choose highlighted differences, overlay or side-by-side view. Adjust tolerance and zoom to inspect a change.
  4. Save the selected difference as a PNG. The export uses the comparison resolution shown beside the page selectors.

FAQ

Is this a text or semantic comparison?

It compares rendered pixels. It does not interpret wording, summarize changes or produce tracked text edits. A changed font, scan position or layout can produce visual differences.

What happens when PDF page sizes differ?

Both pages use the same scale and align at the top left, with white padding. The tool reports different page sizes instead of stretching pages into the same shape.

Can I compare confidential PDFs without uploading?

Yes. PDF reading, rendering, comparison and PNG export run locally in your browser. The site loads its own program and font resources; your documents are not sent to a server.

What are the limits?

Each PDF may contain up to 200 pages and be at most 50 MB. Selected pages render at up to 2× PDF scale with a longest edge of 1600 pixels. Zoom enlarges that preview, not the comparison resolution. Password-protected PDFs are not supported. Embedded fonts are preferred; substituted fonts can affect results.