Compare PDF — Exactly What Changed
Finding what changed in a revised contract by hand is tiring and error-prone. This tool places two documents side by side and points out only what differs.
Comparison works two ways. Text comparison tells you line by line what was added and deleted, catching wording changes precisely. Visual comparison draws two pages at the same scale and compares pixels, making non-text changes like stamps, shapes, and formatting visible.
The two methods complement each other's weaknesses. Text comparison alone can't tell that a font or color changed; visual comparison alone makes everything look different when one line shifts. So by default both run together.
Limits of this tool
- Text comparison only works on PDFs that have text. For scans, only visual comparison is meaningful.
- In visual comparison, one shifted line can make everything below it look different.
- When only one word changes within a line, that whole line shows as delete + add.
- With many high-resolution pages, comparison takes time and uses a lot of memory.
How to use
- 1
Upload two files
Select the original (previous version) on the left and the document to compare (new version) on the right.
- 2
Set the comparison method
Decide whether to include visual comparison and how sensitively to view color differences.
- 3
Review the result
Check the added/deleted lines and difference image per page. You can view only the changed pages.
Key features
Precise line-by-line comparison
Uses the longest common subsequence method to distinguish what stayed and what changed. When paragraph order is preserved, it pinpoints only the changed lines.
Difference image generation
Creates an image with changed pixels painted red to show at a glance where it changed.
Handles different page counts
A page present on only one side is marked as entirely added or deleted.
Page-size change detection
If the page size changed, it flags it separately to prevent print accidents.
When to use it
Checking a contract revision
Confirm that no un-agreed wording changed in a contract the other party revised and sent back.
Document version control
Check the difference between the final and previous version just before submission to catch mistakes.
Translation/proofreading review
Compare before and after proofreading to confirm changes were applied.
How are your files handled?
Both documents open and are compared only in your browser. Neither the content nor the comparison result is sent to a server.
Selected files open only in your browser's memory, and results are handed straight to your device when you save. Close the tab and any remaining data is gone with it. See the Privacy Policy and File Retention Policy for details.