Does it compare how the pages look?

No — it compares the text. Formatting, fonts, images, colours and layout changes are invisible to it. For those, a visual comparison of rendered pages is the right tool.

Why is every line reported as different?

Usually different line breaking between the two exports. Switch on the option to ignore whitespace, which removes that noise and leaves the real changes.

Can it compare scanned documents?

No. A scan holds images of text with nothing to extract. Run OCR on both first, and remember that OCR introduces its own differences where it reads a character differently in each pass.

Are my documents uploaded?

No. Both are read in this tab, which matters given that the usual reason to compare two PDFs is that one of them is a contract someone has just sent back.

Compare PDF

See what changed between two versions of a document.

Everything runs inside your browser. Your files never leave your device.

Drop your files here

.pdf · they stay on this device

Ask about Compare PDF

Questions about what this tool does, which option to pick, or what it can and cannot handle.

The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong. The tool itself is not guessing: it runs deterministic code on your device.

About the Compare PDF

Finding what changed between two versions of a document is a task that gets done badly by reading both. This extracts the text from each and reports the differences.

The comparison is on text rather than on appearance, which determines what it is good for. It will find an altered clause, an inserted paragraph, a changed figure, a deleted sentence — the things that matter in a contract, a policy or a specification. It will not find a changed font, a moved image, an adjusted margin or a different colour, because none of those changes the text.

Options to ignore whitespace and case exist because they remove most of the noise. Two documents exported from different versions of the same software frequently differ in line breaking throughout while saying exactly the same thing, and a comparison that reports every line as changed is a comparison nobody will read.

The obvious use is a contract returned by the other side. "We've made a few small changes" is a sentence that deserves verification, and reading forty pages to find them is not a good use of an afternoon.

Two limits. A scanned document contains no extractable text, so there is nothing to compare — that needs OCR first. And text extraction follows the document's internal ordering, which for a complex layout with columns or sidebars may not match reading order, so a multi-column document can produce differences that are ordering artefacts rather than real changes.

Both documents are read in this browser tab. Sending two versions of a contract to a comparison service is an unusual thing to do with a contract.

How to use it

1Drop in both versions, original first.
2Switch on the whitespace and case options to remove noise from differing export settings.
3Read the differences, which are reported as insertions and deletions.
4Check anything in a multi-column layout by eye, since extraction order may not match reading order.

Questions

Does it compare how the pages look?: No — it compares the text. Formatting, fonts, images, colours and layout changes are invisible to it. For those, a visual comparison of rendered pages is the right tool.
Why is every line reported as different?: Usually different line breaking between the two exports. Switch on the option to ignore whitespace, which removes that noise and leaves the real changes.
Can it compare scanned documents?: No. A scan holds images of text with nothing to extract. Run OCR on both first, and remember that OCR introduces its own differences where it reads a character differently in each pass.
Are my documents uploaded?: No. Both are read in this tab, which matters given that the usual reason to compare two PDFs is that one of them is a contract someone has just sent back.