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Open-Source PDF Software Capable of Comparing PDFs

Compare two PDFs and report differences

2 tools

C++

diff-pdf

CliGui

Compares two PDF files page-by-page and reports whether they differ, either as a simple exit code for scripting or, with `--output-diff`, a new PDF that visually highlights every difference between the two inputs. Also offers a GUI mode for interactive side-by-side comparison with synchronized zoom and page-shifting, useful for spotting translation-only or formatting-only changes between two revisions of the same document. Commonly used in CI pipelines to catch unintended visual regressions.

Python

pdf-diff

Library

Compares the text layers of two PDFs and outputs the bounding boxes of changed text as JSON, identifying exactly which text regions differ between two versions of a document rather than just reporting that they differ. Then rasterizes the changed pages to a PNG with red outlines drawn around the differences, giving a visual diff alongside the structured JSON output. Useful for reviewing what actually changed between two revisions of a generated or edited PDF.