Compare PDF guide
How to Compare Two PDF Files for Visible Differences
Compare two PDF versions by rendering corresponding pages and measuring pixel differences, then use the TXT report to choose which original pages need manual review.
Compare the two PDFs
- Select the older and newer PDF versions in the correct order.
- Confirm that both versions use the expected page order.
- Generate the TXT difference report.
- Open both originals and inspect pages with nonzero or unexpectedly high percentages.
Use the difference report as a review map
The TXT report gives a rendered-pixel difference percentage for each page position. It does not show or highlight the changed areas, and it does not prove that two documents have identical meaning, legal effect, metadata, signatures, or hidden content.
Match corresponding pages first; inserted or removed pages can shift the rest of the comparison and create misleading differences.
- Confirm that both versions use the expected page order.
- Inspect both original pages before deciding what changed.
- Treat the TXT percentages as a review map, not a visual overlay or semantic result.
Review the comparison result
Read every important changed page in both originals instead of treating the percentage as a meaning comparison. The tool does not produce a side-by-side viewer or highlighted result.
FAQ
Does Compare PDF understand semantic text changes?
No. It compares rendered page pixels and reports a percentage per page in a TXT file; it is not a semantic text diff, visual overlay, or legal redline system.
What is the current input limit for Compare PDF?
two PDF files; Two PDFs, each ≤50 MiB, ≤100 pages, render cap 20 MP/page.
What does Compare PDF create?
rendered appearance comparison, not legal/content equivalence; TXT difference report.