Native CAD interfaces
Direct support for the CAD formats listed here.
STEP Viewer
Open STP and STEP files
intuitive & practical 3D without CAD expertise
affordable & universal many 3D/2D interfaces
Modern, easy-to-use CAD viewer
Cost-effective CAD converter for all formats
The 3D-Tool Viewer opens STEP, STP, STPZ, and STPX files without any additional CAD software.
The 3D-NativeCAD Converter converts STEP models to CAD exchange formats such as IGES, JT, SAT, and Parasolid X_T. It also supports visualization formats such as STL, OBJ, 3D-PDF, 3D-HTML, FBX, 3MF, and glTF.
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Windows support
Compatible with current Windows versions.
STEP Files From Customers and Suppliers
A STEP file from a customer, supplier, or partner often arrives without any indication of the CAD system that created it. The 3D-Tool Viewer opens it anyway, making geometry, assembly structure, and dimensions accessible right away, regardless of the original CAD program.
Unlike many free online viewers, 3D-Tool goes beyond pure viewing: wall thickness, angles, and distances can be measured and checked directly. If the file format does not match your own software, the 3D-NativeCAD Converter also transfers the model into another exchange format - useful when no CAD system with a STEP interface is available in-house.
What are STEP and STP files?
- Files with the step or stp file extension contain 3D models in STEP format. The "Standard for the Exchange of Product model data" is one of the most important data exchange formats for 3D designs between applications and companies.
- All major CAD programs can save and open assemblies and parts as STEP files.
- In addition to exact geometric data and assembly structure, a STEP file can also contain triangulated visualization data, materials, colors, and other product information.
- The STEP format is continuously evolving, especially for Product Manufacturing Information (PMI), and will remain an important 3D exchange format in the future.
STEP versions
- AP203 is one of the early STEP application protocols. It transfers geometry, topology, and product and assembly structures of mechanical 3D models. However, the original Edition 1 does not support color information; corresponding presentation information was added with AP203 Edition 2.
- AP214 is a separate application protocol for mechanical design processes in the automotive industry. In addition to geometry and product structures, it supports presentation information such as colors and layers as well as other product and process data.
- AP242 combines the application areas of AP203 and AP214 for model-based 3D engineering. It supports Product and Manufacturing Information (PMI) as well as exact BREP geometry and triangulated geometry.
Special STEP formats
Atomic STEP file: Typically, a STEP file contains the complete model-in the case of an assembly, the entire assembly and all parts. Some CAD programs offer the option of splitting the components of an assembly into multiple part files linked via assembly STEP files.
STPX (STEP-XML): Similar to an Atomic STEP file, these models consist of multiple files. The XML file with the stpx extension contains the assembly structure and additional metadata in text-based, human-readable XML format. The 3D geometry data, meaning the actual 3D parts, is stored in externally linked STEP files.
STPZ / STPXZ: stpz files contain one or more STEP files in compressed form, similar to a ZIP archive. The STEP format compresses well, so the files become relatively small. stpxz files are accordingly compressed projects in STEP-XML format.
How do I open a STEP file without CAD software?
Without a CAD program, open a STEP file with a STEP reader. The 3D-Tool CAD Viewer is a STEP reader and opens all STEP file formats and variants listed above. Professional measurement tools and analyses utilize the full potential of STEP data.
There are also a few free STEP readers and even online STEP viewers for viewing a 3D design in STEP format. However, these are limited to pure viewing.
The usual alternative is CAD/CAM software with a STEP interface. Older interfaces do not always support, or only partially support, more modern formats such as STEP AP242 and STEP-XML.
How can I convert a STEP file?
Convert STEP files with a 3D converter or CAD converter, for example to IGES, SAT, OBJ, or STL. The 3D-NativeCAD Converter in 3D-Tool Premium converts all STEP file formats and many other 3D CAD formats to common 3D exchange formats such as JT, IGES, SAT, and Parasolid X_T. The 3D-Tool Viewer itself converts 3D models to mesh formats such as 3MF, STL, and PLY.
Without a converter or CAD/CAM software with a STEP interface, the model must be exported from the original CAD system. A different 3D exchange format or 3D visualization format is suitable, for example for 3D printing or design software such as Blender.
Try the STEP viewer and STEP converter for free
3D-Tool is a CAD Viewer with interfaces for common native CAD formats and 3D exchange formats. 3D-Tool offers professional measurement tools, draft analysis, and wall thickness analysis.
- Open, measure, annotate, and publish STEP files in all variants for the 3D-Tool Free Viewer or as 3D-PDF
- Open STEP files in all variants and save them as STL, 3DS, PLY, WRL, or OBJ
- Convert STEP data to JT, IGES, SAT, and Parasolid X_T
- Convert STEP models into 3D product visualizations such as 3D-HTML, FBX, 3MF, and glTF
Simply download 3D-Tool, start it, and request a trial key. Test all functions, all interfaces, and the 3D-NativeCAD Converter for 14 days. Open and convert STEP, IGES, SAT, Parasolid, as well as CATIA, Designcenter (Siemens NX), Inventor, SolidWorks, and many other formats.
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Frequently Asked Questions (FAQ)
What is the difference between STEP AP203, AP214, and AP242?
AP203 was developed to exchange configuration-controlled 3D designs of mechanical parts and assemblies. Edition 1 transfers geometry, topology, and product and assembly structures, but no colors. Edition 2 adds colors, layers, and other presentation information. AP214 covers mechanical design processes in the automotive industry with additional product, process, and presentation data. AP242 combines the application areas of AP203 and AP214 for model-based 3D engineering and supports PMI as well as exact BREP and triangulated geometry. Choose an application protocol that the recipient's import interface supports and that carries the information required for the exchange.
Why does my STEP assembly consist of several files?
An Atomic STEP file does not store the model in a single file. It splits the components of an assembly into multiple part files linked via assembly STEP files.
What is the difference between STP, STPX, and STPZ files?
STP/STEP is the standard single- or multi-file format. STPX (STEP-XML) stores the assembly structure and metadata in a human-readable XML file, with the 3D geometry in externally linked STEP files. STPZ and STPXZ are compressed versions of STEP and STEP-XML projects, similar to a ZIP archive. For projects with external references, the recipient needs the associated geometry files as well.
Why won't my CAD software open a STEP AP242 or STEP-XML file?
Older CAD interfaces may not support STEP AP242 and STEP-XML, or may support them only partially. Check which STEP variants the receiving application accepts before exporting. If the file cannot be opened, request an alternative supported STEP variant from the sender rather than simply changing the file extension.
Which formats can STEP files be converted to?
The 3D-NativeCAD Converter in 3D-Tool Premium converts STEP models with exact geometry into JT, IGES, SAT, and Parasolid X_T. The 3D-Tool Viewer also converts STEP models into mesh formats such as 3MF, STL, and PLY. Conversion to exact CAD formats requires exact geometry in the STEP file. AP242 files containing only mesh data do not provide that geometry.