STEP

STEP (Standard for the Exchange of Product model data; ISO 10303-21) is a standardized format for 3D objects used in CAD/CAM. It is a text based format.

Identification
Files begin with the ASCII characters.

Specs

 * ANSI ISO-10303-21 (paywalled)

Software

 * Free viewer
 * STEP file viewers

Programming libraries

 * STEPcode

Online tools

 * Online viewer

Sample files

 * A sample is here
 * More samples are here (ZIP file)

Links

 * Wikipedia article