Native CAD interfaces
Direct support for the CAD formats listed here.
Creo Viewer
Open PRT and ASM files
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Modern, easy-to-use CAD viewer
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The 3D-Tool Viewer opens Creo PRT and ASM files without Creo software.
The 3D-NativeCAD Converter converts Creo models to a wide range of formats such as STEP, IGES, JT, SAT, Parasolid X_T, STL, OBJ, 3DS, PLY, 3D-PDF, 3D-HTML, FBX, 3MF, and glTF.
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Windows support
Compatible with current Windows versions.
What are PRT and ASM files?
- The PRT file extension is used by several programs. In the CAD/CAM field, it refers to native 3D models from either Creo Parametric or ›› Siemens NX. Creo files can often be identified by a number after the file extension (*.prt.1, *.prt.2).
- The ASM file extension is used in CAD/CAM by Creo Parametric or ›› Solid Edge. Creo files can often be identified by a number after the file extension (*.asm.1, *.asm.2).
- PRT is the part file format and contains 3D geometry and, in some cases, Product Manufacturing Information (PMI).
- ASM is the assembly file format and is linked to at least one, but usually several, PRT files and often other ASM files.
Creo Versions
Creo Parametric is the successor to Pro/Engineer. Pro/Engineer was the first parametric 3D CAD system in 1988. From 2002 to 2008 it was called Pro/Engineer Wildfire, and since 2009 it has been part of the Creo suite. PRT and ASM files created with newer Creo Parametric versions cannot be opened with older versions. The current version is Creo 12. (05/2026)
Creo Elements is another application in the Creo suite. It is a direct modeling software application and a further development of CoCreate. Creo Elements has its own native file formats.
Creo View is a family of viewers for visualizing Creo 3D models and 2D drawings.
Additional native Creo file formats
- xpr, xas Optional accelerator files for part variants (xpr) and assembly variants (xas). They optimize performance, but some applications need them to display variants correctly.
- drw Native 2D drawing from Creo Parametric
- pvs, pvz Creo View files containing product visualizations from the PTC Creo Viewer.
- bdl Creo Elements bundle file containing a 3D model and related drawings.
- pkg Creo Elements archive, a compressed file made up of parts, assemblies, drawings, and workplanes.
How do I open Creo PRT and ASM files?
Typically, a Creo installation is used for this. Alternatively, the files can also be opened with CAD/CAM software that has a Creo interface.
The free Creo View Express supports native Creo Parametric parts (prt) and assemblies (asm), but offers no markup capabilities and only simple distance and length measurements.
In addition to PRT and ASM files, the 3D-Tool CAD viewer opens many other CAD formats and offers extensive measurement and analysis functions.
How do I convert Creo PRT and ASM files?
Without CAD software with a Creo interface, the models must be exported from Creo to a common 3D exchange format, such as STEP.
Converting CREO ASM and PRT to STEP is also possible with a 3D converter.
The 3D-NativeCAD Converter in 3D-Tool Premium converts native CREO models and models from many other CAD systems reliably into the standard 3D exchange formats STEP, IGES, SAT, and Parasolid X_T.
Test the Creo viewer and Creo converter for free
3D-Tool is a CAD Viewer with many native CAD interfaces and professional measurement tools, draft analysis, and wall thickness analysis.
- Open PRT and ASM files, add dimensions and comments, and publish them for the 3D-Tool Free Viewer or as 3D PDF
- Open PRT and ASM files and save them as STL, 3DS, PLY, WRL, or OBJ
- Convert PRT and ASM files to STEP, IGES, SAT, X_T, and JT
- Convert Creo models to 3D product visualizations such as 3D-HTML, FBX, Collada, 3MF, and glTF
Free, no-obligation 14-day trial with all features, the Creo interfaces, and the 3D-NativeCAD Converter. The trial key activates all 3D interfaces, including Siemens NX, SolidWorks, Inventor, STEP, SAT, and Parasolid.
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