A PDF compare tool renders both PDF versions side-by-side and highlights pixel-level differences so you can instantly see what changed between documents. Ideal for contract revisions, design proofs, and version control.
Upload PDFs to Compare
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Drop modified PDF or
ORIGINAL
MODIFIED
OVERLAY
Diff Summary
How to Compare Two PDF Files
Comparing PDFs manually is tedious — scrolling between two windows and trying to spot small text edits or layout shifts is error-prone. This PDF compare tool renders both documents at the pixel level and highlights every difference automatically, saving you time on contract reviews, design proofs, and document version control.
Step 1: Upload Both PDFs
Upload your original PDF on the left and the modified version on the right. You can click the "Browse" button or drag-and-drop your files onto each upload zone. The tool reads both files locally in your browser — nothing is sent to any server.
Step 2: Click "Compare PDFs"
Once both files are loaded, click the Compare PDFs button. The tool renders each page from both documents to canvases at the same scale and computes the pixel-level difference. A progress bar tracks the comparison as it processes each page.
Step 3: Choose a View Mode
Three view modes are available. Side by Side shows both versions next to each other — the best mode for spotting layout changes and text edits. Overlay composites both pages at 50% opacity each — differences appear doubled or blurry while identical areas stay clear. Diff Only colors changed pixels red against a faded background, making even small edits immediately visible.
Understanding the Diff Summary
The diff summary at the bottom shows a percentage for each compared page. A diff of 0% means the pages are pixel-perfect identical. A diff of 1-5% typically represents a small text change or a few shifted elements. Diffs above 20% usually indicate major layout changes, added or removed content, or a completely redesigned page. Use the page navigation arrows to jump directly to a high-diff page.
FAQ
Is this PDF compare tool free?
Yes — completely free with no account or signup required. All comparison processing happens in your browser.
Is my PDF data private when comparing?
Yes. Your files never leave your device. Both PDFs are processed entirely in your browser. Nothing is sent to any server.
What is the Diff mode?
Diff mode compares each pixel of both PDF pages and highlights changed areas in red. Unchanged regions appear faintly in the background, making it easy to spot edits at a glance.
What happens if the two PDFs have different page counts?
The tool compares the pages that exist in both files. If one PDF has 5 pages and the other has 8, only the first 5 pages are compared. A notice is shown about the page count mismatch.
What does the diff percentage mean?
The diff percentage shows what fraction of a page's pixels differ between the two versions. A diff of 0% means the pages are identical; 100% means every pixel changed. Even a small text edit typically shows 1-5% difference.
Can I compare scanned PDFs?
Yes — both text-based and scanned (image) PDFs work since the tool renders each page as an image and compares the visual output rather than text content.
What is the overlay mode?
Overlay mode composites both PDFs on the same canvas with one at 50% opacity. Sections where the two versions differ appear blurry or doubled, making it easy to see shifts, additions, and removals at a glance.