nanoCAD and nanoCAD Plus
is a professional grade CAD tool. It has a familiar interface, powerful drafting and design tools, native DWG compatibility, and an open API. And it's totally free to use and share. No catches, no gotchas, and no compromises.
nanoCAD Plus is everything nanoCAD is, and more. It includes even more productivity features, and is available through a low-cost annual subscription, including updates and priority online support. No frills, pure design.