How to Compare Two PDF Files Side by Side Online
Spot text differences, additions, and deletions between two revisions of a PDF document. 100% free, line-by-line comparison in your browser.
Open Compare PDF — free, in your browser
Why compare PDF versions?
When collaborating on contracts, leases, revisions, or technical manuals, identifying small changes—such as altered numbers, omitted clauses, or modified dates—by manual proofreading is exhausting and prone to human error. A visual side-by-side diff highlights every addition and deletion instantly.
Compare two PDF files online · Use text diff checker for plain text
How to compare two PDFs for differences
Open Compare PDF tool · Edit detected errors directly in PDF
- Open the Compare PDF tool.
- Drop the original PDF into Document A and the revised PDF into Document B.
- The comparison engine extracts text streams and computes differences using the Longest Common Subsequence (LCS) algorithm.
- Review side-by-side: additions are highlighted in green, deletions in red, and unchanged text in neutral gray.
- Export or copy the difference report for your records.
When to use PDF Compare vs. Word Track Changes
Word track changes only works when both parties edit the original DOCX file. Once a document is exported to PDF, track changes metadata is discarded. The PDF Gen reconstructed text comparison compares the final output, ensuring you catch changes regardless of which software created the files.
Extract all text to TXT · Count words in PDF before submission
Confidential contract comparison
Legal agreements and bids are strictly confidential. Our diff engine runs entirely inside your client browser tab, ensuring neither document is uploaded or logged.