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PDF→ PDFHeavy on device
Compare PDF Versions
See page-level visual and text differences between two PDF versions without exposing either document.
Processed locallyIn: PDFOut: JSON
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How to use compare pdf versions
Open exactly two PDF versions; both are parsed locally.
Review aligned pages side by side with a visual difference image and normalized text changes.
Adjust visual sensitivity for anti-aliasing or rendering noise.
Analyze every page position and download the local comparison report.
What this tool does
- Page-index alignment with explicit missing-page states
- Side-by-side A/B page renders and magenta pixel-difference view
- Adjustable RGB difference threshold
- Normalized word-count additions and removals for text-layer PDFs
- All-page JSON report with counts and changed-pixel percentages
How the result is verified
Both parser instances stay open while every aligned page position is rendered and measured. Report generation succeeds only after the full page loop completes locally.
Frequently asked questions
Can it compare scanned PDFs?
Yes visually. Text differences require a searchable text layer, but pixel comparison works on scanned page images.
Is my file uploaded to a server?
No. The file is opened with your browser's File API and processed by code running in your tab. You can confirm this yourself: open your browser's developer tools, watch the Network panel, and process a file — no request carries your file's bytes. See our How it works page for a step-by-step verification guide.
Is there a file size limit?
There is no artificial upload limit because there is no upload. Practical capacity depends on your device's memory and your browser. Very large files may be slow or fail to decode on low-memory devices; if that happens the tool fails safely without altering your original file.
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