PDF Diff Tool
pdfdifftool.com ↗Side-by-side revision comparison for architectural drawings. Pixel diff plus word-level text diff, synchronized pan/zoom, annotated PDF export. Runs entirely in the browser — your drawings never leave your machine.
The problem
Architectural drawing revisions are a constant on any project. Finding what changed between a CD set and an addendum — or between two versions of a sheet — is tedious work done by eye or with expensive desktop software. Most AEC firms have no good web-based option, and the good desktop options require uploading confidential drawings to a cloud server.
What we built
A progressive web app that loads two PDF files locally in the browser, renders them side-by-side with synchronized zoom and pan, and runs two passes of diffing:
- Pixel diff — region-by-region visual comparison using pixelmatch, configurable grid size (10–50px).
- Text diff — word-level comparison of extracted text using jsdiff, prioritized in export overlays over pixel diff.
Confidence scoring highlights regions by degree of change. Export produces an annotated PDF with changes marked.
No backend. No upload. All processing runs in the browser — the constraint is intentional, because architectural drawings are often confidential and shouldn't leave the machine.
Current status
Active, fully client-side PWA. Visit pdfdifftool.com to use it.