Compare two PDFs and see what changed
Put two versions of a document side by side and see exactly what changed, word by word, with additions and removals highlighted. Both files are compared entirely in your browser.
Compare PDFs
PDF.js extraction + jsdiff word-level diff
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How to Compare PDFs
- Add the original. Drag the earlier version into the first slot.
- Add the revised version. Drag the newer version into the second slot.
- Compare. Text is extracted from both files and compared word by word.
- Review the result. Removed text is shown struck through in red, added text highlighted in green.
How the comparison works
Both PDFs have their text extracted using the same reading-order reconstruction this site uses for Extract Text — paragraphs joined properly, columns read in the right order, repeated headers and footers stripped out so they don't clutter the comparison as false differences.
The two resulting texts are then compared word by word using a proper diff algorithm — the same class of algorithm behind tools like `git diff` — rather than a naive line-by-line comparison, which would flag an entire paragraph as changed just because one word in the middle was edited.
What this catches well, and what it doesn't
This is a text comparison, not a visual one. It's well suited to contracts, policies, essays and reports where the wording is what matters — a changed clause, an added sentence, a removed paragraph all show up clearly.
It won't catch a change that's purely visual with no text difference — a font swap, a colour change, an image replaced with a similar one, or a layout rearrangement that doesn't alter the words themselves. If exact visual fidelity matters more than wording, this isn't the right tool for that comparison.
Frequently asked questions
Does it matter which file goes in which slot?
Yes, for how the result reads — text removed from the original shows struck through, text added in the revision shows highlighted. Swapping the files would show the same edits from the opposite direction.
Are my files uploaded anywhere?
No. Both files are read and compared entirely in your browser.
Can it compare scanned PDFs?
Only if they already have a text layer. A scan with no text layer will produce empty or near-empty extracted text on that side, making a meaningful comparison impossible — run the OCR tool first.
Will it catch formatting changes like a different font?
No. This compares text content only, not visual appearance, so purely visual changes with identical wording won't be flagged.
Why are some differences I expected not showing up?
Repeated headers, footers and page numbers are deliberately stripped before comparison so they don't create noise — if the change you're looking for was in one of those, it wouldn't appear. Everything else in the body text is compared.
Can I compare more than two files at once?
Not currently — this compares exactly two files. For more than two versions, compare them pairwise.