Compare PDF
Highlight differences between two PDF versions.
or click to browse — supports PDF files up to 100MB
How to use
- 1 Drop or click to upload your file
- 2 Adjust options if shown
- 3 Click Run Tool
- 4 Download your result instantly
- ✓ Files up to 1GB
- ✓ Unlimited jobs/hour
- ✓ Batch processing
- ✓ Priority support
Files are processed securely and permanently deleted within 1 hour. We never store, read, or share your documents.
Why this works
Diff two PDFs side-by-side \u2014 see exactly what changed between two versions of a contract, two drafts of a report, or two versions of a translated document. Highlighted differences make spot-the-change effortless.
Compare is the right tool when you have two PDFs that should be similar and need to know exactly how they differ. Common cases: two versions of a contract during a negotiation where you need to verify every change the other side made; before-and-after exports of a report where you want to confirm only the agreed edits were applied; a translated document compared to its source to verify content parity; an updated policy document compared to its previous version for change-management documentation.
Upload exactly two PDFs. The tool renders them side-by-side and highlights every difference in colour: red for content present in the first PDF but missing or changed in the second; green for content in the second but missing or changed in the first. Differences are detected at the text level (added, removed, or modified words and paragraphs), at the image level (replaced or added images), and at the layout level (significant structural changes).
What it catches well. Text changes: every word added, removed, or modified, down to single-character edits. Inserted or deleted paragraphs: clearly marked with their boundaries. Image substitutions: when an image at a given position has been replaced with a different image. Significant layout changes: a page break that moved, a column that shifted.
What\u2019s harder. Cosmetic-only changes: a font shift from Calibri 11 to Arial 11 with identical content may show as no difference (we focus on content, not visual style). Heavily reformatted documents: when paragraphs got reordered without textual changes, the tool may struggle to match the new positions to the old. Scanned PDFs: image-only sources need OCR first; even then, OCR variance between the two sources can introduce false positives.
Output is a report PDF showing the two source documents side-by-side, with differences highlighted, plus a summary section listing all changes by page. Use the summary to navigate to specific differences during review.
How it works
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1Upload exactly two PDFsDrop both files into the upload box. The first uploaded becomes the \u201coriginal\u201d reference; the second becomes the \u201cnew\u201d version.
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2Run the comparePress Compare. Processing typically takes 5\u201310 seconds depending on document length.
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3Review highlighted differencesThe output PDF shows both documents side-by-side with red for removed-from-original content and green for added-in-new content.
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4Use the summary page to navigateA summary section at the end lists all changes by page so you can jump directly to specific differences.
Real-world uses
Lawyers
Contract negotiation: verify exactly which clauses the other side modified in their counter-proposal.
Compliance teams
Change-management documentation: produce a clear diff of a policy update for audit trails.
Translators
Compare a translated document against its source to verify content parity.
Researchers
Compare two versions of a published paper to track corrections or retractions.
Common questions
How accurate is the comparison?
For text content in born-digital PDFs: highly accurate, down to single-character edits. For image-only or scanned PDFs: accuracy depends on OCR consistency between the two sources \u2014 expect some false positives in the diff output. For documents with heavy reformatting but no real content changes, the tool may show structural differences even when content is identical.
Will it catch a font change?
No by default \u2014 Compare focuses on content (text, images), not visual style (fonts, sizes, colours). For visual-style diffs (typography review), use a side-by-side visual review in a PDF viewer with both documents open.
Can I compare more than two PDFs at once?
No \u2014 the tool compares exactly two documents per run. To compare three versions (v1, v2, v3), run two passes: v1 vs v2, then v2 vs v3, then look at both reports together.
Does the order of upload matter?
Yes \u2014 the first uploaded PDF is the \u201coriginal\u201d reference; the second is the \u201cnew\u201d version. Red highlights content present in the first but not in the second; green highlights content added in the second. Upload in the order you want changes attributed.
Will the original PDFs be modified?
No. Both uploads are read but unchanged. The comparison report is a separate output PDF.
Does it work with scanned documents?
It works, but accuracy drops because OCR is involved in both sources \u2014 OCR variance between two scans of the same content can introduce false positives. For accurate scan comparison, OCR both PDFs separately, manually verify the OCR output, then compare.