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PDF Diff

Upload two versions of a PDF and see exactly what changed — added lines in green, removed lines in red, page by page.

ℹ️ 100% private — both PDFs stay in your browser. Text extraction, diffing, and highlighting all run locally. Nothing is uploaded.
Step 1 — Upload Both PDFs
Original Before
📄
Original PDF

The "before" version

Revised After
📄
Revised PDF

The "after" version

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✅ Diff Report Ready
Revised PDF with change highlights baked in
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⚠️ File expired. Click Compare again to regenerate.
How to use▾
  1. Upload the original (before) PDF and the revised (after) PDF
  2. Click Compare PDFs — text is extracted from every page of both documents
  3. An LCS diff runs on the text lines of each page
  4. Green highlights appear over added lines, red over removed lines
  5. Use the page navigator to step through all changed pages
  6. Download a diff report PDF — the revised file with highlights baked in

Note: Works with digital PDFs only — scanned PDFs with no text layer cannot be diffed.

Frequently asked questions▾
Does this work on scanned PDFs?

No. The tool needs selectable text embedded in the PDF. Scanned PDFs have no text layer so no diff can be produced.

What is "line-level" diffing?

PDF.js extracts individual text items. The tool groups items that share the same Y coordinate into logical lines, then diffs those lines — giving a word-processor-style view.

What if the page counts differ?

Pages only in the revised PDF are marked "New page" (green border). Pages only in the original are "Removed page" (red border).