PDF Compare Tool

Spot differences between two PDF documents side-by-side. See original, modified, and highlighted diff all on the same screen — with a full change count per page.

Side-by-Side View Change Count 100% Private

Upload Original

Drop File 1 here

Upload Modified

Drop File 2 here

Difference Settings
Output Quality
Highlight Color
Comparison Tolerance
Strict
Every artifact
Normal
Skip anti-aliasing
Loose
Ignore minor shifts
Render Resolution
Note: Higher resolution gives more accurate change detection but uses more browser memory. For documents over 30 pages, Standard is recommended.
Analyzing & Comparing…
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Comparison Results
0 changes
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Pages Compared
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Pages Changed
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Pages Identical
0%
Avg Change
Page 1 of 1
Identical
Difference Highlight
Compare PDFs
Upload original and modified versions. The tool renders both files, compares pixels side-by-side, and tells you exactly how many changes exist per page.
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File 1 Pages
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File 2 Pages
3-Panel View — Original, Modified, and Diff panels display side-by-side. Click any page in the results list to jump directly to that page.
Per-Page Change Count — Every page shows the exact percentage of pixels that changed, a bar indicator, and a total count of changed pages vs identical pages.
100% Private — All pixel analysis runs entirely in your browser. Your documents never leave your device.

How to Compare PDFs

1

Upload Files

Drop the Original in the left zone and the Modified version in the right zone.

2

Set Color & Tolerance

Pick a highlight color and tolerance level (Strict catches every pixel, Loose ignores minor rendering differences).

3

Compare & Review

Click Compare. Browse each page in the 3-panel view. The summary shows total changes per page.

4

Download Report

Export a PDF report with all diff pages. Changed areas are highlighted in your chosen color.

Frequently Asked Questions

How does the comparison work?
Both PDFs are rendered to HTML canvases using PDF.js. The tool then sweeps through every pixel mathematically. Matching pixels are faded to grey; differing pixels are painted with your chosen highlight color. The percentage shown is the fraction of total pixels that differ on each page.
What does the change percentage mean?
It shows what fraction of the page's total pixels are different between the two files. A 1% change on an A4 page at High quality (~1240x1754 pixels) represents roughly 21,000 individual pixels that differ — typically a paragraph or two of changed text.
What if the PDFs have different page counts?
The tool compares up to the highest page count. If one file is shorter, its missing pages are compared against blank white, so those extra pages will show as 100% changed (new or deleted pages).
Is my document uploaded to a server?
Never. Both rendering (PDF.js) and pixel comparison run entirely inside your browser using your local CPU and RAM. Your confidential documents are not transmitted over the internet.
No upload · No server · Visual Pixel Diff · Side-by-Side View · Free forever · Pdf Pixy