Compare PDF

Compare two PDF files page by page and highlight visual differences directly in your browser.

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Visual difference sensitivity

Higher sensitivity highlights smaller visual changes.

Compared locally in your browser

Only the active pages are rendered. This is visual comparison, not semantic text comparison or legal interpretation.

What Compare PDF does

Compare PDF renders matching pages from two files, displays both versions, and highlights pixels whose color difference exceeds the selected tolerance.

Choose the right tool: This is a visual PDF difference checker. It is not semantic text comparison, legal review, or change interpretation.

Supported workflow

Original, changed, and highlighted difference views
Page-by-page navigation
Adjustable visual tolerance
Page-count difference warning

Important limitations

The comparison is pixel-based rather than semantic.
Font rendering, antialiasing, or page-size differences can create visual highlights.
Only the active page is compared at one time.

File handling and privacy

Selected files are processed in your browser and do not need to be uploaded to PDFStack servers.

Compare PDF FAQ

How does PDF comparison work?

The tool renders the same page from both PDFs and highlights pixel color differences above the selected tolerance.

Can it compare every page?

You can navigate and compare pages individually. The tool also reports when the documents have different page counts.

Does it compare text meaning?

No. It does not perform semantic, legal, or word-by-word document analysis.

What does the tolerance control do?

A higher tolerance ignores more minor visual differences such as subtle antialiasing changes.

Are the PDFs uploaded?