⚡ 100% Local • No Upload • Free Forever

Compare PDF Files Online – Free PDF Comparison Tool

Upload two PDFs and instantly see the differences highlighted page by page. Perfect for reviewing changes, contract revisions, or document versions. All processing stays in your browser.

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Upload First PDF (Original)

Click or drag & drop — max 50 MB

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Upload Second PDF (Revised)

Click or drag & drop — max 50 MB

Page: Threshold:

Identical Differences Differences: 0 pixels

📄 Document 1 (Original)

No PDF loaded

🔍 Difference Overlay

No comparison yet

📄 Document 2 (Revised)

No PDF loaded

💡 How it works: Upload two PDFs, select a page, and click Compare. The tool renders both pages, compares them pixel by pixel, and highlights differences in red on the overlay. Adjust the threshold to fine‑tune sensitivity.

How the PDF Comparison Tool works

This tool lets you visually compare two PDF documents page by page. It renders each page as an image, then performs a pixel‑by‑pixel comparison. Any pixels that differ beyond the set threshold are highlighted in red on the difference overlay. You can adjust the threshold to ignore minor variations (like anti‑aliasing or compression artifacts). All processing is done locally in your browser – your documents never leave your device.

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UPLOAD

Choose two PDF files

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COMPARE

Select page and threshold

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REVIEW

See differences highlighted

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DOWNLOAD

Save difference image

Step‑by‑step guide

Upload two PDFs. Use the two upload zones to select the original and revised versions.
Choose a page. Enter the page number you want to compare (both documents must have that page).
Set sensitivity. Adjust the threshold (0–255) to control how strict the comparison is. Lower values detect more differences.
Click Compare. The tool renders both pages and generates a difference overlay.
Review and download. The side‑by‑side view and the overlay help you spot changes. You can download the difference image as PNG.

Frequently Asked Questions

Most standard PDFs are supported, including scanned documents (as images) and text‑based PDFs. The tool compares rendered page images.

No. All processing is done locally in your browser using PDF.js. Your files never leave your device.

The threshold determines how much difference in pixel brightness is considered a change. A lower value (e.g., 10) will flag even tiny variations, while a higher value (e.g., 100) will ignore minor anti‑aliasing or compression artifacts.

Currently, you compare one page at a time. You can change the page number and click Compare again to check different pages.

📊 The easiest way to spot PDF differences

Whether you're reviewing a contract, checking a student's homework, or verifying a document revision, our PDF comparison tool gives you a clear visual overview of changes. No sign‑up, no watermarks, and complete privacy. Start comparing now.