SF3 (Simple File Format Family) is a family of open standard file formats, free to use for everyone. These file formats all follow a similar scheme and the same principles.
Included are formats for images, audio, 3D models, rich text, logging, archives, and more. All of the formats are intended to be easy to read and write, and cover base use-cases of various binary formats.
You can find more information about the formats at the links below: