Draw vector diagrams in the plane and on the sphere. Teach and study Euclidean geometry and spherical geometry. A consistent user interface across geometries facilitates interaction with the plane and the sphere. Detailed interactive instructions are provided throughout. Snap to points, lines, and intersections. Finger-based and stylus-based inputs are supported. Hovering (if available on your device) will show the snapping points before you commit. Export to Scalable Vector Graphics (SVG) and to Portable Network Graphics (PNG) images.