Welcome to the biomechanics C3D home - this web site exists to provide detailed and definitive information on the C3D file format. C3D files have been used in Biomechanics, Animation and Gait Analysis laboratories to record synchronized 3D and analog data since 1987. Within this web site you will find: Background information about the C3D file format. C3D file format specifications and design overview. C3D software tools and documentation. Links to companies with software programs that use C3D files. Sample C3D data files.