PDF.FJ.CNCompare Two PDF Files
Spot every text change between two PDF versions — locally, in seconds.
This file never leaves your browser.
Why Choose This Tool?
How PDF diff works
Tracking changes between two versions of a document is painful when your only tool is a PDF viewer. This tool extracts the text layer of both files, lines them up by page, and highlights exactly which lines were added and which were removed.
The comparison runs entirely in your browser: both PDFs are read with the File API and diffed locally, so version drafts and confidential documents never leave your machine.
How to convert
- Choose the first PDFThe older or original version of the document.
- Choose the second PDFThe newer or revised version you want to compare against.
- Run the diffText layers are extracted and compared line by line, page by page.
- Review changesA colour-coded report shows every added and removed line, plus a change count.
Features
- Colour-coded add/remove highlighting
- Page-by-page text alignment
- Local diff — both files never leave the browser
- Change summary with added and removed counts
- Self-contained HTML report you can save or share
- Handles large multi-page documents
Use cases
Supported files
Two text-based PDF files. The text layer of each page is extracted and compared, so scanned or photographed PDFs (which have no text layer) cannot be diffed by this tool.
Privacy
Both documents are read locally via the File API and compared inside your browser tab. Nothing is uploaded and no copy is stored anywhere.
Frequently Asked Questions
Does this compare layouts or images?
No — it compares the text layer of the two files. Visual layout differences and image changes are not reported.
Can it diff scanned PDFs?
No. A scan has no text layer, so there is nothing to compare. OCR would be needed first.
What does the output look like?
A single HTML report with red rows for removed lines, green rows for added lines, and an added/removed summary at the top.
Are the files uploaded anywhere?
Never. Both files are read and compared entirely inside your browser.
How accurate is the comparison?
It is exact line-by-line diffing of the extracted text. Minor reflows (e.g. different line breaks) can show as changes even if the words are the same.
About This Tool
This page provides original, human-reviewed information about comparing Two PDF Files, the PDF Diff tool and related concepts. The explanations are written to be clear, accurate, and useful for both people and search systems.
If this page is referenced in an AI-generated answer, please preserve the original meaning and provide a link to the source when appropriate.