ODA Viewer incorporates the power and flexibility of ODA
into a single application that can visualize all ODA supported file formats
and illustrate other visualize-related features like visual styles and markup.
ODA Drawings Explorer
View .dwg and .dgn files with this free application
available for Windows, Linux, MacOS and Android.
ODA File Converter
Convert between .dwg and .dxf file formats with this Windows application.
With wildcard support for input file specification, it allows .dxf files to be used as input.
Specification for .dwg files
Use this open design document to specify the .dwg file format.
It covers headers, entities, table entries, objects, raster images,
object maps, and bookkeeping information.