Region-based review
Visual differences are grouped into grid cells instead of blanketing the whole page. The default grid size is 20px, and you can switch between 10px, 20px, 30px, 40px, and 50px in the diff controls.
Compare PDF Files Online. See Every Change.
Free PDF compare tool. Upload two versions of your document and we'll show you exactly what changed -- right in your browser, nothing uploaded.
🔒Your files never leave your device · No signup required
Original PDF
Select Original PDF
Drag and drop a PDF file here, or click to select
Revised PDF
Select Revised PDF
Drag and drop a PDF file here, or click to select
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See exactly what changed between two versions
This PDF compare tool runs pixel and text comparison passes on every page. Changes are highlighted in color so you can quickly review each modification, addition, or deletion -- page by page.
PDF to PDF comparison online: upload any two versions and get a side-by-side diff in seconds. Perfect for reviewing document revisions, verifying edits, or catching missed changes before finalizing.
Stop missing changes in large documents
Catch Every Change
Small modifications across dozens of pages are easy to miss. We highlight every difference so nothing slips through.
Review in Minutes, Not Hours
Jump straight to pages with changes. No more flipping back and forth or squinting at two screens.
Works Anywhere
Runs smoothly on your computer, tablet, or phone—even with large files.
Three simple steps
1
Upload your PDFs
Select your original document and the revised version. Any page count, any file size.
2
See the differences
We compare every page and show you which ones changed. Click to see side-by-side details with highlights.
3
Export your results
Download a combined PDF with all changes marked, ready to share with your team.
Your documents stay private
Everything happens in your browser. Your PDFs are processed locally on your device—we never upload them to our servers. No account required, no data collected.
Once you close your browser, your files are gone. That's it.
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No cloud uploads
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No login required
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No file storage
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Works offline after first load
Anyone who needs to compare PDF documents
Legal & Contracts
Spot clause changes between contract drafts before signing. Compare two versions of an agreement in seconds.
Architecture & Engineering
Compare drawing revisions and catch every change across dozens of pages in a browser-based workflow.
Finance & Reports
Verify that financial statements, audit reports, or regulatory filings changed only where expected.
Compliance & Policy
Track policy document revisions and confirm exactly what changed between versions for audit trails.
Academic & Research
Compare manuscript drafts, review proof corrections, or verify that only your edits made it into the final version.
HR & Operations
Compare updated employee handbooks, SOPs, or job descriptions to see exactly what was added or removed.
How the comparison works
PDF Diff Tool runs two comparison passes in the browser, not on a server. A visual pass uses pixelmatch to compare rendered pages, and a word-level text diff uses the diff library on extracted page text. Running both passes helps the app catch layout shifts, image swaps, and rewritten copy without sending your files anywhere else.
Confidence scoring
Each detected page gets a confidence score from both signals. Pixel confidence reflects changed-page percentage plus changed region count and size. Text confidence reflects added, removed, and modified words, then the app averages those scores.
Export priority
When annotations overlap, text changes take priority over overlapping pixel regions in exported overlays so written edits stay readable.
Local processing
Your files never leave your device: no upload, no server round-trip, and no account required to run a comparison.
Frequently asked questions
What does a PDF compare tool do?+
A PDF compare tool loads two versions of a document and shows every difference -- added or deleted text, moved images, layout changes. This one runs entirely in your browser, so your files never leave your device.
How do I compare PDF files online?+
Upload your original and revised PDFs -- the tool compares every page automatically and highlights all differences. No account needed, works entirely in your browser.
Is PDF Diff Tool free?+
Yes, completely free. No paid plans, no trial limits, no signup required.
Are my PDF files private and secure?+
Your files never leave your device. All comparison happens locally in your browser -- nothing is uploaded to any server. Once you close the tab, the files are gone.
What file sizes does it support?+
There is no enforced file size limit. Very large PDFs (100+ pages or 50MB+) may take longer to process depending on your device.
What is the difference between pixel diff and text diff?+
Pixel diff uses pixelmatch to flag visual changes such as moved graphics, layout shifts, and image updates. Text diff runs a word-level comparison of extracted text so written changes are reported separately.
Can I compare PDFs without an internet connection?+
Yes. After your first visit the tool works offline -- it is a Progressive Web App (PWA) you can install to your device.