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PDF Comparison

Highlight text differences between two PDFs.

Use the PDF Comparison tool

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What this pdf comparison does

PDF Comparison extracts the text layer from two documents and runs a line diff. It shows what was added, removed and left unchanged, together with a per-page summary so you can jump to the parts that moved.

The comparison relies on extractable text. A scanned PDF has only images, so it needs OCR before any text comparison can work. Layout changes, font changes and image edits are not detected.

Why use it

  • Review a contract revision without reading both documents side by side.
  • Check that a generated report matches the approved version.
  • Confirm which pages changed after a template update.

How to use it

  1. 1Select the older PDF and the newer PDF.
  2. 2Wait for the text layer to be extracted.
  3. 3Read the added and removed lines and the page summary.
  4. 4Download the diff as a text file for your records.

Worked examples

One clause changed

Input

Version A: “Payment is due in 30 days.” Version B: “Payment is due in 45 days.”

Output

One removed line and one added line show the changed sentence.

Scanned document

Input

A PDF containing only page images

Output

No text is extracted, so the tool reports that there is nothing to compare.

Common mistakes

  • Comparing a scan with a text PDF and concluding nothing changed.
  • Ignoring whitespace-only differences that the line diff normalises.
  • Assuming unchanged text means unchanged pages; images and layout can still differ.

Frequently asked questions

Does it compare formatting?
No. It compares extracted text lines. Colour, font, spacing and images are not part of the diff.
Is there a page or size limit?
The tool processes up to 100 pages and 50 MB per file. Larger documents should be split first.
Can it compare password-protected PDFs?
No. Remove the password in a PDF reader first, then compare the unlocked copies.
Are the files uploaded?
No. Extraction and comparison run in the browser using pdf.js and a local diff algorithm.

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