Embroidermodder

 
Embroidermodder is a free machine embroidery software tool that supports a variety of formats and allows the user to add custom modifications to their embroidery designs.
History.
Embroidermodder 1 was started by Mark Pontius in 2004 while staying up all night with his son in his first couple months. When Mark returned to his day job, he lacked the time to continue the project. Mark made the decision to focus on his family and work, and in 2005, Mark gave full control of the project to Josh Varga so that Embroidermodder could continue its growth.
Embroidermodder 2 was conceived in mid 2011 when Jonathan Greig and Josh Varga discussed the possibility of making a cross-platform version. It runs on Linux, macOS, Microsoft Windows.
The Embroidermodder website and downloads are hosted on SourceForge. On July 18, 2013, The Embroidermodder 2 Source was moved to GitHub.
libembroidery.
One of the byproducts of Embroidermodder 2 was the creation of libembroidery library. libembroidery is written in C. It supports reading and writing of a variety of embroidery formats, and several vector formats which are not commonly used in embroidery.
The formats are as such (last updated January 2017):
'Stable' = Yes, supported and is considered stable.
'Unstable' = Yes, supported but may be unstable.
No = Not supported.