Free Document Comparison Tool: Compare Text & Detect Diff Online

Document Comparison — Find Every Change Between Two Versions Instantly

Contract negotiation produces multiple document versions over days or weeks, with each party's counsel making changes that need to be tracked and reviewed. A proposal revised after client feedback contains modifications that must be identified before the updated version is approved. A regulatory document updated between published versions requires systematic comparison to identify all changes for compliance review. Visually comparing two versions of a long document page by page is error-prone and slow — important changes in dense text are easy to miss. Document comparison highlights every difference between two versions automatically.

Comparison output formats serve different review workflows. A redline view — showing deleted text in strikethrough red and added text in green — is the standard legal and contract review format where both old and new content must be visible simultaneously for evaluation. A summary list of changes by page and line number enables rapid navigation to each change without reading intervening unchanged content. A side-by-side view displays both versions with synchronized scrolling and change markers aligned across documents. The comparison tool generates all three output formats from a single comparison operation.

PDF comparison handles both text-based PDFs and scanned image PDFs with different techniques. Text-based PDFs compare text character sequences directly — additions, deletions, and substitutions are identified at the character level. Scanned PDFs require image-difference analysis — pixel-level differences are highlighted as changed regions, though this method cannot distinguish meaningful content changes from scan quality variations. For the highest accuracy comparison of scanned documents, OCR both PDFs first and then compare the recognized text rather than comparing the underlying images.