OwlCAD is described as 'Free browser-based parametric CAD for 3D printing. Model, repair and export print-ready STL, 3MF, OBJ, GLB, STEP and DXF. No install, no account' and is a 3D Modeler in the photos & graphics category. There are more than 10 alternatives to OwlCAD for a variety of platforms, including Mac, Windows, Web-based, Linux and Self-Hosted apps. The best OwlCAD alternative is FreeCAD, which is both free and Open Source. Other great apps like OwlCAD are SketchUp, Akse, OpenSCAD and Onshape.
OwlCAD alternatives are mainly 3D Modelers, but if you're looking for
CAD Software or 3D Printing Tools you can filter on that. These are just examples - use the filter bar below to find more specific alternatives to OwlCAD.