Compare PDF
Compare two PDF files and visualize differences page by page. Upload two PDFs, adjust comparison settings, and download a diff PDF highlighting changes.
Original PDF
No file selected
Pages: -
Modified PDF
No file selected
Pages: -
Upload two PDF files to compare. They should have the same number of pages for accurate comparison.
Compare PDF Online – Visual Difference Detection
The Compare PDF tool helps you identify visual differences between two PDF documents. Whether you're comparing contract versions, report revisions, design mockups, or document updates, this tool shows exactly what changed between two PDF files page by page.
The tool works by rendering each PDF page as an image and then comparing the pixels. Differences are highlighted in your chosen color, making it easy to spot modifications, additions, deletions, or formatting changes. The output is a new PDF that displays the original and modified pages side by side with differences clearly marked.
How to Compare Two PDF Files
- Upload the original PDF (first file) and the modified PDF (second file).
- Wait for the tool to detect page counts.
- Adjust comparison settings: render quality, sensitivity, and output mode.
- Click "Compare PDFs".
- Wait while the tool processes each page (this may take time for large PDFs).
- Download the comparison PDF that shows differences.
Main Features
- Visual page-by-page comparison with pixel-level accuracy.
- Adjustable sensitivity to detect small or large changes.
- Multiple output modes: side-by-side, differences only, or both.
- Custom highlight color for differences.
- Compare selected page ranges.
- Works entirely in your browser for privacy.
- No software installation required.
When to Use PDF Comparison
This tool is ideal for:
- Comparing contract revisions and legal documents.
- Tracking changes in reports and proposals.
- Reviewing design mockups and layouts.
- Checking updated manuals or documentation.
- Verifying that no unauthorized changes were made.
- Auditing document versions.
Important Notes
Visual vs Text Comparison: This tool compares the visual appearance of pages, not the underlying text structure. Minor text changes that don't affect layout (like correcting a typo in the same position) will be detected, but text reflow or formatting changes may cause many pixel differences even if the content is similar.
Page Count: For accurate comparison, both PDFs should have the same number of pages. If page counts differ, the tool will compare up to the minimum page count and note the discrepancy.
Performance: High-resolution PDFs and large documents take longer to process. Adjust render quality and sensitivity based on your needs.
Privacy and File Safety
All processing happens locally in your browser. Your PDF files are never uploaded to any server, ensuring complete privacy and security of your sensitive documents.
Frequently Asked Questions
Is this Compare PDF tool free?
Yes, this tool is completely free to use directly in your browser without limitations.
Are my PDF files uploaded to a server?
No. All processing happens locally in your browser. Your files never leave your device.
Can I compare PDFs with different page counts?
Yes, but comparison will only be done for pages that exist in both files. The tool will report if page counts differ. For best results, use PDFs with the same number of pages.
What does the sensitivity setting do?
Sensitivity controls how different two pixels must be to be considered a change. Lower values detect even minor differences (like anti-aliasing variations) while higher values only flag significant visual changes.
Why is my comparison slow for large PDFs?
Comparison requires rendering each page to an image and comparing every pixel. Higher render quality and lower sensitivity increase processing time. For large documents, this can take several minutes.
Can I compare scanned PDFs?
Yes, but scanned PDFs are image-based anyway, so visual comparison works well. However, minor scanning variations (like slight misalignment) may be detected as differences.
What do the different output modes mean?
Side by Side: Shows original and modified pages next to each other, with
differences highlighted on the modified side.
Differences Only: Shows only the pages where differences were detected,
with differences highlighted.
Both: Includes both the side-by-side view and a separate differences page.
Will this detect text changes?
Yes, if the text change affects the visual appearance. However, this is not a text-level diff tool. For pure text comparison, use a text-based diff tool after extracting text from PDFs.
Can I adjust the highlight color?
Yes, you can choose any color for highlighting differences in the comparison output.
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