Zones: teal bands run along every wall (30 cm above the floor, 30 cm below the ceiling, 115 cm in kitchens), amber bands beside corners, doors and windows. Outlets snap to the preferred lines.
Click a wall to open its wall view. There you drag outlets to the right height; the numbers in the PDF are measured the same way.
Click a room and type a wall's length on the right, e.g. 5 or 4.35 m. The corners beyond it move along, so a rectangle stays a rectangle. Type a new area instead and the room grows or shrinks in its shape.
"Measure" (M) draws dimension lines, "Text box" (T) adds notes for your electrician. Both work in the floor plan or right on the wall in the wall view, and the PDF shows them in the same place.
The circuits tab suggests one circuit per room for sockets, one per floor for lighting and one per large appliance. "Circuits → panel" opens them as a board in the panel planner.
Put a socket on the outside of an outer wall and I turn it into an IP44 outdoor socket automatically. Outdoors it needs at least that protection rating. Set it back to an indoor socket in the inspector and I will grumble.
Nothing leaves your browser: plans live in local storage, in a JSON file or in the share link.