# Compare PDF Files

> Two versions of a contract, one diff view. The viewer lays the documents side-by-side or as a single overlay with a draggable slider, and highlights every region of changed pixels in red. A separate Text Diff modal opens word-level changes line by line. Both source files stay in the browser tab — useful when the diff includes deal terms, manuscript revisions, or design proofs that shouldn't touch a vendor's server.


Live tool: https://lofttools.com/tools/pdf-tools/compare-pdf

Category: PDF & Documents


## What it does

- Side-by-side and overlay diff modes with draggable slider
- Word-level text diff with line numbers in a modal (split or unified)
- Pixel-level layout diff highlights — covers reflow, spacing changes, and image shifts (anything that changes the rendered page)
- Page rail with per-page diff badge + A/B preview stack
- Right pane comparing metadata, bookmarks, form fields, and fonts side-by-side
- Apple-style transparent ruler overlay with px / in / mm units
- Drag-rect exclusion zones to ignore page numbers / timestamps / margins
- Jump-to-next-change with F7 / Shift-F7
- Multi-page PDFs handled in browser memory (no per-page upload)
- Both source files stay in the browser tab — no server upload

## How it works

1. **Drop two PDFs in the splash** — Drop or pick an Original and a Modified PDF. Comparison fires automatically once both files are loaded.
2. **Compare** — Pixel diff with smart morphology runs in your browser; differences in text, images, and layout are highlighted on every page.
3. **Navigate changes** — Use the page rail, F7 to jump to the next change, or open the line-numbered text diff modal.

## FAQ

### What types of differences are detected?

Text additions, deletions, and modifications are highlighted. Layout and image changes are also shown.

### Does this preserve bookmarks and form fields?

Yes. The output PDF inherits bookmarks and form fields from the chosen base document; the diff overlay is added as annotations.

### What PDF versions are supported?

PDF 1.0 through 2.0 are diffed page-for-page. Encrypted files need to be unlocked first.

## Privacy

This tool runs entirely in the browser. Files are not uploaded to a server. They never leave the user's device.

## More

- All tools: https://lofttools.com/tools
- Category: https://lofttools.com/tools/pdf-tools
- LLM index: https://lofttools.com/llms.txt