Compare two PDFs
Comparing two versions of a document is a common job and a badly served one. The tools that work on the text layer are precise about what changed, and useless on a scan, because a scan has no text layer to compare. The tools that work on pixels will compare anything and tell you much less about what it means. Knowing which of the two you are holding is most of the decision, and the fastest way to find out is to try the file: a text based tool will usually tell you plainly that it cannot read your document.
4 tools here do less than the name of this job suggests, and each one's profile says what it actually does. That sentence is on the profile rather than repeated on every row.
4 options · Sources read 29 September 2026 · We tested one text comparison tool against a document with a known difference and against a scan, and recorded exactly what it did. We have not benchmarked comparison accuracy, and one of the tools here was added to this index the same day it was tested.
- What it takes, and what it produces
- In: two documents. Out: a report of the differences between them.
- What limits it
- Text comparison and visual comparison find different things, so a clean text report does not mean the pages render identically. File size and page count are capped per tool where they are capped at all.
Compare tools: controls, file handling and cost
These are different ways to do the same job. The order does not indicate quality, and where we have not checked something the row says so rather than guessing.
- 4
- tools handle this job
- 1
- keep the file on your device
- Observed by us, or no server anywhere in the path. Of the other 3: 3 process some versions on your device and run others on a server.
4 tools for comparing
Ordered by relevance to this job, not by payment. Our overall ranking is in the full index.
Every listing here is a real product with a real website, checked for whether it is still working. Nothing on this page is paid for and no placement can be bought. Where we have not verified something, the row says so rather than guessing.
Choosing between comparing the text and comparing the pictures
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Comparing the text
Reports added, removed and changed words with page references, and needs both documents to have a text layer. Precise about wording and blind to anything that is not text.
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Comparing the pictures
Compares what the pages look like, so it catches a moved signature, a changed logo or a shifted margin. It cannot tell you what a difference means, and it reports every rendering difference as one.
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What happens with a scan
A scanned document often has no text layer, though a scan that has been through OCR has one. With no text layer a text comparison has nothing to read and will refuse the file; with one it compares the recognised text rather than the page as it looks, and the two can disagree. Image-only pages inside an otherwise readable document need checking separately, because a difference on one of those is not reported. It is a common reason a comparison does not run, and it is worth knowing before you start.
Check the result
- - Put a change you already know about into the test, and check the tool reports it. A comparison that finds nothing looks identical to a comparison that failed.
- - Check whether image-only pages were skipped, because a difference on one of those will not be reported.
- - Read a reported change in context. Moving a paragraph and rewording it can both be reported as the same kind of change.
Sources and scope
Every fact on this page comes from a vendor's own page. Each profile records the URL we read, the date, and the SHA-256 of the text, so a reader can check the bytes.
- PDF Compare 5 sourced claims, read 29 September 2026
- Adobe Acrobat 4 sourced claims, read 21 September 2026
- Foxit PDF Editor 2 sourced claims, read 22 September 2026
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