# Compare PDF — Free Online (PdfPixels)

> Compare selectable text in two PDF documents with line-by-line redline highlighting for additions and deletions.

Canonical URL: https://www.pdfpixels.com/tools/compare-pdf
Processing: server
Cost: free, no signup required for core use.

## Short answer

Compare PDF highlights differences, additions, and deletions between two document versions with line-by-line redline diffing in seconds.

## About

Compare PDF Documents provides line-by-line text comparison between two versions of a PDF file. During contract negotiations, legal drafting, architectural revisions, and policy updates, identifying subtle text changes, clause additions, and removed stipulations between document drafts is critical. Manually reading through dozens of pages side-by-side is slow and error-prone. Our comparison engine extracts content streams from both files, computes line-level diffs, and displays a responsive redline view highlighting additions in green, deletions in red, and unchanged text. You can inspect revision metrics, and copy the redline text to your clipboard.

## Key features

- Dual upload dropzone for effortless Version 1 (Original) and Version 2 (Revised) comparison
- Line-level redline highlighting (Green = Added, Red = Deleted)
- Change breakdown dashboard showing total additions, deletions, and percentage similarity
- Scrollable text comparison; images, layout, and formatting are not compared
- Zero account creation required with fully private, temporary document analysis

## How to use

1. **Upload Original PDF** — Upload the initial baseline agreement, draft, or version 1 document.
2. **Upload Revised PDF** — Upload the modified version, counter-proposal, or version 2 document.
3. **Automatic redline diffing** — Our comparison engine analyzes text streams and maps line-level additions and deletions.
4. **Review text diff** — Inspect highlighted changes (green for added, red for removed) and copy the redline text.

## FAQ

### How does the PDF comparison engine detect changes?

The engine extracts selectable text in page order and compares added and removed lines. Large inputs are rejected rather than silently truncated.

### How does redline diffing help in contract negotiation?

In contract law and commercial agreements, counter-parties often send back revised agreements without turning on "Track Changes". Our redline diff instantly exposes every altered clause, changed payment term, or omitted warranty, protecting you against hidden counter-party edits.

### Does Compare PDF show visual image and diagram differences?

Compare PDF focuses on text stream analysis, detecting line-by-line wording alterations, modified numbers, and clause insertions. For visual image changes or graphical edits, viewing the two pages side-by-side or exporting pages to image format provides complementary inspection.

### Can I compare contracts with different page counts?

Yes. The comparison engine is content-driven rather than page-bound, meaning it accurately identifies added or deleted clauses even if pagination has shifted.

### Is my confidential contract data secure during comparison?

Yes. Files are sent to the server over HTTPS and processed for this request. Comparison responses are marked no-store.

### Can I download the redline comparison as a report?

Yes. Use Copy Redline to copy the text changes, then paste them into your own report.

## Limits

- PDF tools: 50 MB per file. Merge: 20 files / 100 MB total / 1000 pages.
- Image tools: 25 MB, 50 MP max. AI tools: 20 MB.
- Rate limits: 20/min per processing route per IP.
- Server-side files are processed ephemerally and purged automatically within 60 minutes.

More tools: https://www.pdfpixels.com/tools — Full machine reference: https://www.pdfpixels.com/llms-full.txt