Open Source PDF Comparator: Compare Two PDF Files Locally

PDF Comparator is a local and open-source tool designed to quickly compare the text content of two PDF files.

It extracts text from both documents, applies light normalization to their content, then displays the differences detected between the two versions.

The goal is to provide a simple way to identify textual changes made to a document without relying on an external platform, API or artificial intelligence system.

What's Included in PDF Comparator?

Application & Comparison

Main Script pdf-compare.py contains the PDF comparison logic
Text Comparison Detection of added and removed lines between two PDF files
Local Processing Comparison performed on your machine, without APIs or file transfers

Documentation & Examples

Bilingual Documentation Complete README documentation available in English and French
PDF Examples Original and modified PDF files ready to test in English and French
Video Demonstrations Two demonstrations show the comparison of the provided example files

How Does the Comparison Work?

Content Extraction

The pdf-compare.py script extracts the text content from the pages of both PDF files provided when it is executed.

Light normalization is then applied to the content before comparing the reference document with its new version.

Difference Detection

Differences are displayed directly in the terminal as added and removed lines.

If no textual difference is detected, the tool simply indicates this instead of producing an unnecessary report.

Processing is performed locally, without sending files to a third-party service or using an external API, an approach consistent with data security principles.

See PDF Comparator in Action

Demonstration of the local comparison of two PDF files, with text extraction and identification of added or removed lines.

▶ Watch the demonstration on YouTube

Installation and Usage

The project requires Python 3 and the pypdf library.

Install the dependencies: python -m pip install -r requirements.txt
Compare two PDF files: python pdf-compare.py old.pdf new.pdf

The first file is the reference version. The second is the new version to compare.

Limitations and Use Cases

PDF Comparator compares the text content extracted from the documents. It does not visually compare page rendering, images, fonts, colors or graphical layout.

The quality of the comparison also depends on the text that can actually be extracted from the PDF. A document containing only images or originating from a scan without an exploitable text layer cannot be compared correctly.

The project is open source under the MIT license.

➜ View project on GitHub

Download project

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