---
title: Compare PDFs
description: Compare two PDF documents side by side or in overlay mode with detailed change detection and categorization.
---

# Compare PDFs

Upload two PDFs and see exactly what changed between them. The tool pairs pages intelligently, detects differences in text, images, annotations, headers, and formatting, and presents them in a side-by-side or overlay view.

## How It Works

1. Upload two PDF files -- the original (left) and the revised version (right).
2. The tool pairs pages between the documents using content signatures.
3. Select a view mode: **Side by Side** or **Overlay**.
4. Navigate between page pairs using the pagination controls.
5. Differences are highlighted and categorized. Use the filter panel to focus on specific change types.
6. Optionally export the comparison as a PDF report.

## Features

- Automatic page pairing based on content similarity
- Side-by-side and overlay comparison views
- Change categorization: text, image, header/footer, annotation, formatting, background
- Per-category filter toggles to show or hide specific change types
- Text change search with query filtering
- OCR support for comparing scanned documents
- Zoom controls for detailed inspection
- Synchronized scrolling between panels in side-by-side mode
- Export comparison results as a PDF

## Options

| Option               | Description                                                                                     |
| -------------------- | ----------------------------------------------------------------------------------------------- |
| **View Mode**        | Side by Side or Overlay                                                                         |
| **OCR**              | Enable/disable OCR for scanned document comparison                                              |
| **OCR Language**     | Language for OCR text extraction                                                                |
| **Category Filters** | Toggle visibility of text, image, header/footer, annotation, formatting, and background changes |
| **Change Scope**     | In overlay mode, filter between all changes or content-only                                     |
| **Zoom**             | Adjust magnification level for detailed inspection                                              |

## Use Cases

- Reviewing contract revisions to find exactly what changed between versions
- Comparing design mockups to verify that PDF exports match expectations
- Auditing document changes in regulated industries where every edit must be tracked
- Verifying that a PDF conversion process preserved the original content accurately
- Checking translation documents against the source for layout changes

## Tips

- The overlay view stacks both documents on top of each other, making spatial differences (shifted elements, resized images) immediately visible.
- Enable OCR when comparing scanned documents that do not have a text layer. The comparison engine will extract text from page images.
- Use category filters to focus on what matters. For example, hide formatting changes when you only care about text content differences.

## Related Tools

- [View Metadata](./view-metadata)
- [OCR PDF](./ocr-pdf)
- [Merge PDF](./merge-pdf)