Reviewing PDF revisions — contract changes, form updates, spec revisions — is tedious with just Acrobat's built-in compare. The Rankato Compare tool renders both PDFs side by side, runs text and pixel diffs, and highlights every change. Text differences appear inline (green for added, red for removed); layout differences appear as pixel overlays. Great for legal review and content sign-off workflows.
Text diff
The tool extracts text from both PDFs (using pdf.js), aligns them page-by-page, and shows a word-level diff. Added text is green; removed text is red; changed regions get both. Useful when you're tracking specific wording changes in contracts.
Visual diff
Both PDFs render to canvas and the tool computes pixel-level differences per page. Overlays highlight moved elements, changed images, and layout shifts. Best for design revisions where text hasn't changed but graphic elements have.
Limitations
Text diff assumes both PDFs use similar page counts and order. Wildly restructured documents produce noisy diffs. Visual diff can't tell if two visually different pages are semantically equivalent (e.g., same content in a different font).