Onionskin
PDF markup for structural drawing review. Native on the Mac.
Download for macOSVersion 279.cb44a5a · macOS 26 or later, Apple silicon · notarized by Apple
Built for drawing sets, not documents
- Navigation that holds still — wheel zoom at the cursor, and the view stays on the same grid as you move sheet to sheet.
- Callouts with multiple leaders — one note, arrows to every place it applies.
- Scale and measurement per page — calibrate a 1:100 plan and a 1:20 detail in the same set; lengths, areas, counts, a legend.
- Vector snips — lift a detail from one sheet and paste it transparently onto another, still crisp at any zoom.
- Revision overlay — two issues of a sheet colour-separated on top of each other, aligned by picked points.
- A tool library — beam symbols, standard notes and steel sections at true scale, placed in a keystroke.
- Exports anyone can open — flattened PDFs with every markup burned in, plus CSV of measurements.