What is Compare PDF?
Compare PDF extracts embedded text from two PDFs, reports each page count, shows the two text results side by side, and states whether the extracted strings are exactly identical.
It is not a visual, pixel, formatting, annotation, metadata, or semantic diff. Scanned pages without text layers may appear empty unless OCR is performed separately.
Why Use This Tool?
The tool provides a quick way to inspect whether two digital PDFs expose the same text and page count, while keeping both files in the browser.
- Compare extracted text strings
- Check page counts
- Copy either text result
- Review versions side by side
How Does This Tool Work?
PDF.js extracts page text items from both documents. Items are joined with spaces under page markers. The tool compares the complete resulting strings with exact equality and separately reads each page count.
There is no highlighted word-level diff or normalization. A spacing, ordering, or page-marker difference can make results unequal.
Understanding Your Results
“Extracted text is identical” means only that the generated strings match exactly. The PDFs can still differ in images, fonts, colors, layout, links, comments, metadata, attachments, or hidden content.
Why Tracking This Matters
Version review needs a method suited to the risk. This text comparison is a useful screening step, but it cannot establish complete document equivalence.
Benefits of Using Compare PDF
- Two-document local comparison
- Exact extracted-text equality check
- Page-count reporting
- Side-by-side readable output
- Copy controls for both results
- No file upload
How Is the Result Calculated?
The result is identical only when the two page-labeled extracted strings are exactly equal. Page-count equality is reported separately.
Text identical = extracted string A === extracted string B
Tips for Better Results
- Use OCR first for scanned documents.
- Review images and layout separately.
- Do not infer byte-for-byte identity.
- Check page count alongside text.
- Use specialized visual diff software when appearance matters.
- Verify high-stakes changes manually.
Conclusion
Compare PDF is a focused embedded-text and page-count check. Treat it as a fast review aid, not proof that two PDFs are visually, structurally, or cryptographically identical.