PDF Compare

PDF Compare lets you check what changed between versions of a PDF by comparing their embedded text layers page by page. Add two to five PDFs, mark which one is the original, and the tool lines each other file up page by page against it, highlighting lines that were added (green) and removed (red) with a side-by-side view.

This is a text-layer comparison, not a visual or pixel diff. It reads the actual words stored in each PDF and compares them, so it is ideal for verifying that a contract, report or spec changed only in the intended places. Layout shifts, font or color changes, and swapped images are not reported because they are not text. Scanned, image-only pages contain no selectable text, so they are shown as empty and unchanged. Pages are matched on the shortest shared page count — pages that exist in only one file are not compared.

Comparison runs entirely in your browser. Files up to 100 MB and 200 pages each are supported, and the honest limit holds: matching is line-based, extra spaces are already collapsed when lines are read, and reordering a paragraph counts as removing and re-adding its lines. A downloadable .txt report summarises every change against each revision.