QCAD is a free, open source application for computer aided drafting (CAD) in two dimensions (2D). With QCAD you can create technical drawings such as plans for buildings, interiors, mechanical parts or schematics and diagrams. QCAD works on Windows, macOS and Linux. The source code of QCAD is released under the GPL version 3 (GPLv3), a popular Open Source license.

New version of famous dxf to g-code converter is available. 
Program supports dxf files with splines & have a lot of benefits, one of them is free for use.
 

• Block and Insert import fully supported
• Spline import with convert to Arc and Line elements to reduce geometry count
• Ellipse import with convert to Arc elements