A STEP file is a 3D model file formatted in STEP (Standard for the Exchange of Product Data), an ISO standard exchange format. It contains three-dimensional data in a format that can be recognized by multiple programs, such as Dassault Systemes SolidWorks, IMSI TurboCAD, and Autodesk Fusion 360.

In the CAD industry, it can be difficult to share models between users with different CAD systems. The STEP format was developed as a solution to this problem. It is designed to be used similarly to how the .PDF format is used for saving documents in a widely supported format. Because of the interoperability of the format, STEP files are often shared between CAD users that use different programs to open the 3D models. NOTE: STEP model files often use the .STP file extension.