unfleece
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Compare PDFs

Render two PDFs locally and produce a page-by-page visual difference report.

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Overview

About Compare PDFs

Reach for this when you have two versions of a document and want to know which pages actually changed. It opens both PDFs with pdf.js, renders each page to an image in your browser, and walks them pixel by pixel, then writes a plain-text report listing every page and how many pixels differ. This catches visual changes a text search would miss, like a moved logo, a tweaked figure, or a reflowed paragraph. It compares appearance, not the underlying bytes, so it is not a cryptographic file hash. Pages that differ in size are reported as fully changed.

How it works

How to compare pdfs

1

Add your file

Drop it in or click to choose. It stays on your device.

2

Set options

Tweak the settings, or just use the sensible defaults.

3

Download the result

One click. It was built right here, in your browser.

The honest difference

Why Unfleece vs fleeceware

Unfleece

  • Runs in your browser — no file upload
  • Free, no account, no card
  • Open source (AGPL-3.0)
  • No file-size paywall

Typical fleeceware site

  • Uploads your file to a server
  • $1 trial → ~$50 / week
  • Closed and opaque
  • Locks results behind pay
Questions

Frequently asked

What does the report actually tell me?
It gives you a page-by-page text summary listing, for each shared page, whether there were no pixel differences or how many sampled pixels differ and what percentage that is. It also notes any page-count mismatch and ends with a one-line summary of how many pages changed. The output is text, not an annotated or highlighted PDF.
What do the render scale and pixel threshold options do?
Render scale sets how large each page is drawn before comparison, so a higher scale catches finer differences but uses more memory and time. Pixel threshold sets how much a pixel's combined color and transparency must change before it counts as different, letting you ignore tiny rendering noise by raising it.
What happens if the two PDFs have a different number of pages?
It compares only the pages the two files share and reports the page-count difference separately at the top. Pages that exist in just one file are not pixel-compared, and any shared page whose rendered dimensions differ is reported as fully changed.
Are my files uploaded anywhere?
No. Both PDFs are read into memory and rendered and compared entirely in your browser on your device. Open the Network tab and run it — you will see no file-upload request.
Keep going

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