Compare PDF Files
Compare two PDF documents page by page and find changes in their extractable text.
Results
Page-by-page results
Select a page to inspect both versions side by side.
Page preview
Select a resultText differences for the selected page will appear here.
How to Compare PDF Files Online
PDF documents are often used for reports, contracts, invoices, study materials, forms, and business records. It is common to receive a revised copy of a document and need to know what changed from the earlier version. Checking two long files manually can take time, especially when the edits are small or spread across many pages. A PDF comparison tool helps organize this review by checking the text that can be extracted from each document and showing which pages appear to be the same or different.
What Does a PDF Comparison Tool Do?
This online PDF comparison tool reads two PDF files in your browser and examines their extractable text page by page. It reports pages with matching text, pages with changed text, and pages that appear in only one of the documents. When you select a result, the tool displays a page preview from each file and provides a text summary to help you investigate the change.
The comparison is useful for reviewing updated drafts, checking revised policies, comparing study notes, and identifying text changes in business documents. It is designed as a practical first review, not as a substitute for a legal, financial, or professional document audit.
How to Compare Two PDF Documents
- Choose the original document. Upload the first PDF in the Original PDF A area.
- Choose the revised document. Upload the second PDF in the Updated PDF B area.
- Set comparison preferences. You can ignore extra spaces and line breaks, and optionally ignore uppercase or lowercase differences.
- Start the comparison. Select Compare PDFs and allow the browser to read the pages.
- Review the report. Check the page statuses, select a page, and inspect the previews and text excerpts.
- Save a report. Download the plain-text summary when you need a simple record of the comparison.
Understanding the Comparison Results
A Same result means that the extracted text on the corresponding pages matches under the selected comparison settings. A Changed result means the text is different. A page marked Only in PDF A or Only in PDF B means that one document has an additional page at that position. The total page count may differ, so later pages are compared by page number rather than by an advanced semantic alignment algorithm.
For changed pages, the report provides a simple text excerpt showing material that appears in the original and revised page. This helps you locate an edit quickly, but it is not a character-by-character proofing system. Always read the full page when the exact wording matters.
Frequently Asked Questions
1. Can I compare two PDF files for free?
Yes. This tool is designed to compare two PDF files directly in a supported web browser. Your files are processed locally by the browser code rather than uploaded to the Nawssai website.
2. Does the tool show exactly what changed?
It identifies pages whose extractable text differs and provides a text excerpt to guide your review. It does not provide a complete legal redline or a perfect character-level comparison. Review the full page for important documents.
3. Can it compare scanned PDF documents?
Scanned PDFs often contain page images instead of selectable text. This version does not run OCR, so it may report little or no text even when the scanned pages look different. Use OCR first or compare the page images with a dedicated visual comparison tool.
4. Will it detect changes in images, charts, or formatting?
No. The comparison is based on extractable text. Changes to photographs, charts, colors, fonts, spacing, or page layout may not be detected. The side-by-side preview is provided for a visual check.
5. What happens if the two PDFs have different page counts?
The tool compares pages by their page number. Extra pages at the end or between the documents are identified as pages that appear in only one file. It does not automatically match moved pages across the two documents.
6. Can I compare password-protected PDFs?
PDFs that require a password may not open in this version. If you are authorized to use the document, create an accessible copy with the correct password and compare that copy.
7. Are my documents uploaded or stored?
The comparison runs in your browser using the selected files. The tool code does not send the PDF contents to a Nawssai upload server. The PDF.js library is loaded from a public CDN, and normal browser or network-provider activity may still apply.
8. Can I use the report as proof that a document has not changed?
No. The report is an aid for checking text differences, not a certification, digital signature, or forensic verification. For contracts, regulated records, or legal evidence, use an approved document-control or forensic review process.
Tips for More Reliable Results
Use PDFs that contain selectable text whenever possible. If a document was created by scanning paper, run OCR before comparing it. Make sure both files are readable and are not damaged or password-locked. Keep the original files unchanged, and inspect every page marked as different. If a document contains tables, footnotes, columns, or complex formatting, check the visual previews because text extraction may not preserve the original reading order.
Privacy and Technical Limitations
The comparison is performed in the browser and the tool does not include an upload endpoint for document contents. For confidential files, use a trusted and up-to-date device and browser, and avoid public computers. This tool compares extracted text only. It does not perform OCR, compare embedded images pixel by pixel, validate digital signatures, or certify that a file is authentic. Large files may require additional memory and take longer to process.
Make Document Reviews Easier
Comparing PDF versions can make routine document checks more organized. Use the page report to find likely text changes, inspect selected pages side by side, and save a summary for reference. For important documents, combine this first-pass comparison with a careful manual review and any approval process required by your organization.