Overlay PDF revisions, annotate drawings with clouds, arrows and dimensions, and measure directly to scale — all from your browser. Built for architects, engineers, and construction professionals.
Purpose-built tools for comparing revisions, marking up drawings, and communicating changes — without the bloat of enterprise software.
Load a base drawing plus two overlay layers. Control opacity independently to isolate exactly what changed between revisions.
Click-to-draw revision clouds with automatic bump profiles, closed-polygon area calculations, and freehand pen for quick markups.
Set a known dimension, then measure anything on the drawing at true scale. Supports mm output with real-world accuracy.
Upload entire drawing sets at once. When new revisions arrive, bulk re-link by filename — all annotations stay in place.
Save your complete project as an .overlay file — sheets, calibration, annotations, everything. Export annotated PDFs or JSON data.
Rectangles, circles, ellipses, diamonds, triangles, lines, arrows with text labels, and comment bubbles. Colour, weight, and dash style controls on everything.
You shouldn't need a $600/year desktop application to compare two PDFs.
Drop in a base PDF and one or two overlay revisions. Batch upload handles entire drawing sets at once.
Adjust layer opacity to spot differences. Set a known dimension to enable true-scale measurements across the drawing.
Add revision clouds, dimensions, text notes, arrows, shapes — the full toolkit. Everything is editable and repositionable.
Export annotated PDFs for distribution, or save the .overlay project file to return and continue later.
No tiers, no per-seat charges, no hidden costs. Just the tools you need.
OVERLAY gives you exactly what you need to compare and mark up drawings — nothing more, nothing less.