For our model viewer we only support IFCs. For our document section we support all file types, but we do not support preview of other file types than:
PDF
Images
DWG
DXF
Office formats
Point Clouds (only .e57 and .las)
IFC
Accepted (Official and retired releases by BuildingSMART)
IFC 4
IFC 4.3
IFC 4.0
IFC 2
IFC 2.3
IFC 2.2
IFC 2.1
IFC 2.0
IFC2.0
Not accepted (Withdrawn by BuildingSMART)
You can find what IFC releases are official here