Compare PDFs
Compare rendered pages for visual differences.
Compare PDFs
Drop your documents here
or choose files from your device
How to use Compare PDFs
Compare PDFs renders two PDFs page by page at 72 DPI and reports the percentage of pixels that changed on each page. You set the pixel difference threshold from 0 to 255 and the maximum number of pages compared, up to 200. Pages with different dimensions or missing from one file are flagged in the results table.
- Choose a source file. If the tool accepts multiple files, arrange them in the order you want.
- Adjust the basic settings, then open Advanced mode for export and fine-tuning options. Custom settings stay active when the panel is closed.
- Run compare pdfs, review the output, then use the available copy or download controls.
What this tool supports
Compares rendered pages at 72 DPI with a configurable pixel threshold. A zero visual difference does not establish semantic or digital-signature equality.
- Pixel difference threshold
- Range: 0 to 255
- Maximum pages compared
- Range: 1 to 200
Limits and processing
PDF input is bounded to 20 MB per file. Page rendering is capped at 200 selected pages; page-edit output is bounded to 500 pages.
Frequently asked questions
How do I find differences between two versions of a PDF?
Select exactly two PDFs and run the comparison. The table lists each page with its percentage of changed pixels, so pages near 0% look the same and higher values point to visual edits.
What does the pixel difference threshold do?
A pixel counts as changed only when one of its color channels differs by more than the threshold, which defaults to 20 on a 0 to 255 scale. Raise it to ignore slight rendering noise, or set 0 to catch every difference.
If two PDFs show 0% difference, are they identical files?
Not necessarily. The check compares rendered appearance only, so it does not prove that the text content, metadata or digital signatures are the same.
Where is my input processed?
This operation processes its source in your browser. Copy and download are explicit actions; source input is not saved in an account or history.
What are the input limits?
PDF input is bounded to 20 MB per file. Page rendering is capped at 200 selected pages; page-edit output is bounded to 500 pages.