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How to compare two versions of a PDF on a Mac

Spot what changed between two versions of a contract or report on a Mac, side by side in Preview or word for word with two free commands.

The problem

A revised contract arrives with a note saying only the dates changed. You want to know, not trust, that nothing else did.

Can Preview compare two PDFs?

No, Preview has no compare tool. You can open both and put the windows side by side, which works for a few pages and misses things on many.

How do I compare two PDF files on a Mac?

Extract the text of each with the free poppler tools, then let diff list every line that changed:

brew install poppler
pdftotext -layout old.pdf old.txt
pdftotext -layout new.pdf new.txt
diff old.txt new.txt

Lines starting with < are only in the old version, lines with > only in the new. We tested it on two versions of a made agreement where two numbers changed: diff printed exactly those two clauses, 30 days notice becoming 60 and 14 days to pay becoming 7, and nothing else. For a side by side view, opendiff old.txt new.txt opens FileMerge if Apple's developer tools are installed.

What does a text comparison miss?

  • Pictures, signatures and layout: only text is compared.
  • Scans: they have no text until you make them searchable.
  • Reflowed paragraphs: a line break moved by one word shows the whole paragraph as changed, though the words are the same.

Our take

Compare the text even when the changes were described to you. A list of changes is what someone meant to change; diff is what they did change, and the two disagree often enough that a minute in Terminal is worth it for anything you sign.

In Simply PDF

Simply PDF's PDF to text gives clean text from each version to compare, and Make Searchable handles scans. Both need a key.

Tested on 16 October 2026 on a MacBook Air (M1), macOS 27.0.1, with two PDFs made by cupsfilter from text files that differed in two numbers, pdftotext from poppler, and the system's diff.

Questions

How do I compare two PDF files on a Mac?

Extract the text of both with pdftotext and compare them with diff, or open them side by side in Preview.

Can Preview compare PDFs?

No. It has no compare tool.

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