123DX is a 3D model file native to free software 123D Design. Autodesk, developer of said software, no longer actively develops its product – the final version was released in 2017.

123D Design alllowed users to perform simple operations on 3D models using various smart tools. 123DX files can also be easily exported into other formats supported by 3D printers. Developer offers for additional price access to database of various predefined models.