Compare PDFs

What does the comparison look at?

The words in each PDF’s text layer, in reading order across all its pages. It reports the words that were removed from the original and the words added in the revised version, with the page each change is on. Capitals, punctuation and the order of words count; line breaks and spacing do not.

Why does a change show up where I only moved a paragraph?

A moved paragraph is removed in one place and added in another, so both appear. Words that are the same but reflowed onto different lines do not count as changes. A word split by a hyphen at a line end can show as a change, because the file stores it as two pieces.

Does it compare scanned pages?

Not with this tool. A scanned page is a picture of text with no text layer, so there are no words to compare, and the result names those pages instead of treating them as the same. Scanned pages need text recognition before they can be compared, which this tool does not do.

What does it miss?

Anything that is not text. A changed image, a signature, a table redrawn with the same words, a highlight, or a change to the layout is not reported. Read the pages by eye for those, and treat a result of no changes as “no text changed”, not “nothing changed”.

Are my files uploaded?

No. Both files are read inside your browser, and the comparison and the report are made there. Nothing is sent to a server.