Compare PDF
View two PDF pages side by side and highlight their visual differences. Comparison runs entirely in your browser.
Upload two versions of a PDF and see their pages compared side by side with visual differences highlighted, pixel by pixel. Because it compares rendered output rather than text, it catches changes text-based diff tools miss - font swaps, moved images, color shifts, or a table that reflowed differently. Useful for reviewing a redlined contract revision or checking a design proof against an approved layout. Comparison runs entirely in your browser via PDF.js.
Runs on your device. This tool processes your file inside this browser tab. Nothing is uploaded, so it also works offline once the page has loaded, and closing the tab discards the file from memory.
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Details
- Category
- Documents & PDF
- Formats
- Runs
- In your browser
- Files uploaded
- No
- Cost per run
- Free
- Sign-in
- Not required
- Works offline
- Yes, once loaded
Last updated 2026-08-12
Common questions
What does the comparison detect?
It compares rendered pixels, so text, image, color, layout, and annotation changes are visible.
Why is a whole area highlighted?
Small layout shifts can move many pixels. Increase the threshold to ignore subtle anti-aliasing and color changes.
Do the two PDFs need the same page count?
Comparison works page by page, so pages are matched by position - documents with different page counts compare only the overlapping pages.
Are my PDFs uploaded anywhere?
No - rendering and pixel comparison both happen locally in your browser.
Use this from your code
This tool is also a REST endpoint, so you can run it in a pipeline instead of by hand. Each call costs 3 credits and needs an API key. See the API reference for every parameter.
curl -X POST https://fileoven.com/api/v1/tools/compare-pdf \ -H "Authorization: Bearer sk_live_..." \ -F "file_a=@input.pdf" \ -F "file_b=@input.pdf"