Compare two versions of a PDF: tips and tools

Why comparing PDF versions is tricky

PDF is a format designed for display, not editing or comparison. Text is often stored as separate text blocks without the structure of a Word document. Standard PDF viewers don't show a "diff" the way word processors can. Nevertheless there are effective ways to spot differences.

Method 1: extract text and compare

Use the PDF to Text tool on PDFrust to convert both PDF versions to plain text. Paste the texts into a text comparison tool like diffchecker.com, Beyond Compare or the built-in diff in VS Code. Text differences will be clearly highlighted. Downside: formatting changes (color, font, layout) are not visible.

Method 2: Adobe Acrobat Compare Documents

Adobe Acrobat Pro has a built-in Compare Documents feature that layers both PDFs and highlights changes. This is the most accurate method for both text and formatting changes, but requires an Acrobat Pro subscription.

Method 3: visual comparison with overlay

For drawings, layouts and forms a visual overlay works well. Merge the two PDFs with the Merge tool and use the Organize tool to place them side by side. With a PDF viewer (Adobe Reader, Foxit) you can then compare page by page by flipping between them.

Check metadata for version differences

View the metadata of both documents with the Info tool on PDFrust. Metadata contains the creation date, modification date, author and software used. Differences in modification date show which version is more recent. This quickly confirms you have the right version.

Merge for side-by-side comparison

Merge both PDFs into one document (version A on odd pages, version B on even pages) to easily flip between them in a PDF viewer. Use the Merge tool for this, and the Even/Odd tool if you want to separate them again afterwards.

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