Arch Offset is a Geometry Nodes modifier that provides CAD-style 2D curve offsetting capabilities in Blender. It includes operations for single-sided, two-sided, and nested offsets. The system resolves overlapping geometry issues on complex curves, such as spirals, by utilizing a closed offset calculation that handles intersecting curve normals. Additional parameters allow users to constrain offset distances on a per-curve basis and generate solid geometry from the 2D offset results.