How to use
- Choose the original PDF on the left and the revised PDF on the right.
- Click Compare.
- Review the list of changes. Untick Show changes only to see the full side-by-side text.
Options explained
- How it compares
- The text of both PDFs is extracted with pdf.js, extra whitespace is removed and lines are aligned. A deletion followed directly by an addition counts as one edit and is compared word by word.
- Page numbers
- Each change shows its page in the original and the revised file so you can find it.
What a change looks like
The comparison works on lines of text, after trimming spaces and dropping blank lines. Suppose the original page has three lines and the revised one has three different lines:
| Original | Revised |
|---|---|
| Payment is due within 30 days. | Payment is due within 45 days. |
| Late fees apply. | Governing law: Delaware. |
| Governing law: Delaware. | New clause added. |
The result is three entries: one edit where “30” became “45” and the line “Late fees apply.” was removed, one unchanged line, and one added line.
Because lines are compared as a whole, a paragraph that has been re-wrapped into different lines, for example after a font or margin change, can show up as an edit even though the wording is the same. Word-level marks then show you that nothing but the line breaks changed.
Frequently asked questions
Can it compare scanned PDFs?
No. Scans contain images, not text; they need OCR first.
Does it show formatting or image changes?
No, only text. Fonts, colors, layout and images are ignored.
Are my files uploaded?
No. Both PDFs are read only in your browser.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.