Utilore

Compare Two PDFs

Someone sent back the contract and said “minor edits”. Finding those edits by eye across twelve pages is how mistakes get signed. Here both files are opened inside this tab and compared — as text and as pictures of the pages.

Old version

or drop them here

A PDF, up to 30 MB

New version

or drop them here

A PDF, up to 30 MB

Both files stay on this device: they are opened inside the tab and nothing is uploaded. That matters here more than usual — contracts and invoices are exactly what people compare.

Text differences are found in scanned PDFs only if the scan has a text layer — a photograph of a page has no text to compare. The overlay works on any pages.

Nearby: Compare Two Texts · Merge PDF · Split PDF · PDF Editor

How to use

  1. Choose the old version and the new one — both must be PDFs.
  2. Press “Compare”. The text differences appear page by page; identical pages are hidden.
  3. Switch to “Page overlay” to see what moved, and download the report if you need it in writing.

Good to know

Two kinds of difference, because two kinds of question

A lawyer and an accountant look for words: a deadline changed, a sum changed, an account number changed. A designer and anyone signing off a layout look for movement: a block shifted, a stamp appeared, the logo slid two millimetres. These are different questions and one answer does not cover both, so this page gives both. The text view lists the lines that were added and removed; the overlay draws the two pages on top of each other — red for what was there, green for what appeared.

Why the overlay has a tolerance

Rendering the same PDF twice does not give identical pixels: font smoothing is allowed to differ by a few units along the edges of letters. Without a tolerance, two copies of one file would be reported as different, and the tool would be useless on exactly the case it is meant for. So dots count as changed only when the brightness differs by more than a set amount, and a page counts as changed only when enough dots do. The numbers are in the code, not in a marketing claim.

What identical pages get: nothing

A forty-page contract with one edit should open on the edit, not on the title page. Pages where nothing changed are counted in the summary and then hidden — both in the text list and when picking a page for the overlay, which opens on the first page that actually differs. Pages that exist in only one file are named added or removed rather than reported as an error: a version with a page inserted is a normal outcome of comparing, not a failure.

Frequently asked questions

Are the files uploaded anywhere?

No. Both are opened inside this browser tab and compared there. It matters more here than usual: what people compare are contracts, invoices and reports.

Why does it find no text differences in my scan?

Because a scan is a picture of a page. If the scan has no text layer, there is no text to compare — recognise it first, or use the page overlay, which works on any pages.

The pages look the same but the overlay shows a percentage. Why?

Because something moved by less than the eye notices — a line spacing, a margin, a stamp. Look at the coloured dots on the overlay: red is what was there, green is what appeared.

Can I compare files with a different number of pages?

Yes. Pages are matched in order; the extra ones are listed as added or removed. Comparison does not stop because one file is longer.

How large a document can it take?

Up to 30 MB per file and the first 200 pages. Beyond that the drawing of pages takes longer than anyone wants to wait, and the page says so instead of freezing.

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