Compare PDF Files and Highlight Differences
Compare PDF files to find visible changes between two versions of a contract, report, or design export. The browser renders shared pages and compares their pixels at your chosen resolution and sensitivity. You receive a text report, red-highlighted PNGs for changed pages, and a page-count note when lengths differ. This is a visual comparison rather than a semantic text or metadata diff, and both PDFs stay on your device.
Choose files or drag & drop here
.pdf · multiple files allowed
Processed locally in your browser — your files never leave your device.
How to compare PDFs
- Upload the two PDF versions — the first is treated as the original.
- Choose the render resolution and how strict the comparison should be.
- Download the diff report and per-page highlight images.
Verified behavior and practical limits
Last tested:
How it processes your file
The browser renders shared pages from two PDFs, compares their pixels at the chosen sensitivity, and creates a text report plus highlighted images for changed pages.
Verified behavior
- Reports visually matching and changed shared pages.
- Marks changed regions in red PNG images.
- Notes when the two documents have different page counts.
Important limits
- This is a visual pixel comparison, not a semantic text, metadata, or legal redline.
- Different fonts, antialiasing, or export engines can create pixel changes even when wording is unchanged.
Reproducible example workflow
- Input
- Original and revised versions of the same three-page contract.
- Action
- Use Normal sensitivity and review the report and highlighted pages.
- Expected output
- A diff report plus PNGs showing visible changed regions.
Continue the workflow
Frequently asked questions
What counts as a difference?
Pages are rendered to images and compared pixel by pixel, so any visible change is caught — moved text, swapped fonts, added images. Invisible metadata changes are not detected.
What if the two PDFs have different page counts?
Shared pages are compared one by one, and the report notes the page-count difference so nothing is silently ignored.
Why did an unchanged page get flagged?
Tiny rendering variations between exports can shift pixels by a hair. Switch sensitivity to Loose to ignore sub-visible noise and flag only real edits.