STP File Extension

What is a STP file?

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STP files contains 3D (three-dimensional) object data saved in Standard for the Exchange of Product Data (STEP) format. STP files are saved in text-based ASCII format containing STEP ISO Application Protocols.

STP files contains information about 3D objects and their primary use is transferring 3D graphics between different CAD and CAM systems. Because their ASCII structure, STEP files are easy to read, with one instance per line. The STEP format is defined by ISO 10303-21 Clear Text Encoding of the Exchange Structure.

There are three editions of ISO 10303-21. First edition was released in 1994 and last was released in 2016. In last edition added is anchor, reference and signature sections to support external references, support for compressed exchange structures in an archive, digital signatures and UTF-8 character encoding.

ISO 10303-21 structure it contains two sections, header and data section. Header section has fixed structure consisting 3 to 6 groups in given order. The DATA section contains application data according to one specific express schema encoded following some simple principles.

How to open STP file?

Programs that open .stp files:


STP Viewer
Autodesk Fusion 360
Dassault Systemes CATIA
CADSoftTools ABViewer


IMSI TurboCAD Deluxe v10
Autodesk Fusion 360
STP File Extension 2018-12-20