Upload two PDF files and compare them side by side. Scroll both panels together, flip pages, and spot differences visually — all in your browser.
PDF File A
Original / First version
Click or drag to upload
PDF File B
Updated / Second version
Click or drag to upload
Upload both PDF files to enable comparison
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Diff Active
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PDF A —
PDF B —
Comparison Summary
How to Compare Two PDF Files Online
1Upload PDF File A (your original or first version) by clicking the left upload panel or dragging the file onto it.
2Upload PDF File B (the updated or revised version) on the right panel. The Compare button activates when both files are loaded.
3Click Compare PDFs Side by Side — both documents render in sync. Scroll one panel and the other follows automatically.
4Toggle Highlight Differences to overlay red pixel-diff highlighting on PDF A — instantly revealing visual changes between the two versions.
Why Use This PDF Comparison Tool?
Side-by-Side Visual Comparison — Both PDFs render next to each other at the same zoom level, making it easy to spot layout, text, and image differences at a glance.
Synchronized Scrolling — Scroll either panel and both move together, so corresponding sections always stay aligned. No manually repositioning two windows.
Pixel-Level Difference Highlighting — Toggle diff mode to see exactly which pixels have changed. Changed areas appear in red, unchanged areas stay transparent, giving you a precise visual diff overlay.
Comparison Summary — See page count for each PDF, number of differing pages, and total pages at a glance in the summary stats panel.
100% Private — No Server Upload — Both PDFs are loaded and rendered entirely in your browser using PDF.js. No file is ever sent to any server. Safe for confidential contracts and legal documents.
Frequently Asked Questions
Can this tool detect text changes — like a word that was edited?
This tool provides visual pixel-level comparison — not text-level diff. It can show you where on the page something changed (highlighted in red), but it does not extract text to tell you which specific words were changed. For text-level comparison, you would need to extract the PDF text first.
What happens if the two PDFs have different numbers of pages?
The tool renders pages up to the maximum page count. For pages that exist in one PDF but not the other, the missing side shows a placeholder panel. The comparison summary also highlights the page count difference between the two documents.
Are my PDF files uploaded to a server during comparison?
Never. Both PDFs are rendered entirely in your browser using PDF.js — a Mozilla open-source library. No files are sent to QuickPDFOnline's servers or any third-party. You can safely compare confidential contracts, legal documents, and sensitive reports.