Native CAD interfaces
Direct support for the CAD formats listed here.
SolidWorks Viewer
Open SLDPRT and SLDASM files
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The 3D-Tool Viewer opens SolidWorks SLDPRT and SLDASM files without SolidWorks software.
The 3D-NativeCAD Converter converts SolidWorks models to a wide range of formats such as STEP, IGES, JT, SAT, Parasolid X_T, STL, OBJ, 3D-PDF, 3D-HTML, FBX, 3MF, and glTF.
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Stable, precise CAD data processing.
Windows support
Compatible with current Windows versions.
Check SolidWorks Models From External Senders
SolidWorks files regularly move between companies that don't run SolidWorks themselves - for example when a job shop, customer, or service provider receives an SLDPRT or SLDASM model for review. The 3D-Tool Viewer opens these files directly, with full assembly structure, and provides tools for measurements, wall thickness, and draft analysis.
Beyond simple viewing, the 3D-NativeCAD Converter turns SLDPRT and SLDASM models into STEP and other common exchange formats - for example to continue working in your own CAD system or to prepare a part for manufacturing.
What are SLDPRT and SLDASM files?
- Files with the SLDPRT and SLDASM file extensions are native 3D files from SolidWorks CAD/CAM software.
- SLDPRT is the part file format and contains one or more 3D geometries and, in some cases, Product Manufacturing Information (PMI).
- SLDASM is the assembly file format and is linked to at least one, but usually several, SLDPRT files and often other SLDASM files.
- SolidWorks is aimed primarily at small and medium-sized mechanical engineering companies. From the beginning, the focus was on simple, user-friendly operation.
SLDPRT and SLDASM versions
New SolidWorks releases with numerous new features appear every year. Releases use the year as their version designation.
Older releases cannot open file versions created with newer releases. Starting with SolidWorks 2024, you can save models back by up to two versions. To do so, the design must not contain features that are not available in the older version. Otherwise, you must suppress those features before saving.
In 1995, SolidWorks was the most affordable and easiest-to-use 3D CAD system, both in terms of operation and hardware requirements.
Additional native SolidWorks file formats
- slddrw Native 2D drawing from SolidWorks, derived from a SolidWorks 3D model
- slddrt SolidWorks template file. Contains drawing sheet templates for creating 2D drawings
- SolidWorks uses the Parasolid modeling kernel. Parasolid X_T and X_B files are 3D exchange formats without a modification history. However, they are the preferred choice for exchanging 3D models between CAD/CAM programs with a Parasolid kernel. These include Designcenter (Siemens NX), SolidWorks, and Designcenter Solid Edge.
How do I open SLDPRT and SLDASM files?
Typically, a SolidWorks installation is used for this. Alternatively, the files can also be opened with CAD/CAM software that has a SolidWorks interface.
The free eDrawings supports native SolidWorks parts, assemblies and drawings and offers simple markup and measurement functions.
The 3D-Tool CAD viewer also opens SLDPRT and SLDASM files, but provides extensive measurement and analysis tools. 3D-Tool can be tested free of charge for 14 days.
How do I convert SolidWorks SLDPRT and SLDASM files?
Convert SLDPRT and SLDASM files to STEP with a 3D converter. The 3D-NativeCAD Converter in 3D-Tool Premium reliably converts native SolidWorks models and models from many other CAD systems into common 3D exchange formats. Available target formats are STEP, IGES, JT, SAT, and Parasolid X_T. For exchange with Designcenter (Siemens NX) and Designcenter Solid Edge, the Parasolid X_T or X_B format is specifically recommended when exporting from SolidWorks. The file format comparison lists the supported SolidWorks releases and shows which edition provides the SolidWorks interface and converter.
Without a converter or CAD software with a SolidWorks interface, the remaining option is to export from SolidWorks to a common 3D exchange format, such as STEP.
Test the SolidWorks Viewer and SolidWorks Converter for free
3D-Tool is a CAD Viewer with many native CAD interfaces, including SolidWorks, as well as professional measurement tools, draft analysis, and wall thickness analysis.
- Open SLDPRT and SLDASM files, add dimensions and comments, and publish them for the 3D-Tool Free Viewer or as 3D PDF
- Open SLDPRT and SLDASM files and save them as STL, 3DS, PLY, WRL, or OBJ
- Convert SLDPRT and SLDASM files to STEP, IGES, SAT, X_T, and JT
- Convert SolidWorks models to 3D product visualizations such as 3D-HTML, FBX, 3MF, and glTF
Free, no-obligation 14-day trial with all features, the SolidWorks interfaces, and the 3D-NativeCAD Converter. The trial key activates all 3D interfaces, including Designcenter (Siemens NX), CATIA, Inventor, STEP, SAT, and Parasolid.
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Frequently Asked Questions (FAQ)
What is the difference between SLDPRT and SLDASM files?
SLDPRT is SolidWorks' part format, containing one or more 3D geometries and sometimes PMI. SLDASM is the assembly format, linked to at least one SLDPRT file and often other SLDASM files. To share a complete assembly, provide the SLDASM file together with its referenced parts and subassemblies. An assembly file alone does not replace the linked component files.
Can newer SolidWorks files be opened with an older SolidWorks release?
Generally not. Starting with SolidWorks 2024, you can save a model back by up to two versions. This only works if the model does not contain features that are unavailable in the older version, or if you suppress those features first.
How can I open SLDPRT and SLDASM files without SolidWorks?
3D-Tool opens SLDPRT parts and SLDASM assemblies without a SolidWorks installation. The viewer provides measurement and analysis tools for inspecting the models. A free 14-day trial allows you to evaluate these functions using your own files before choosing an edition. Include referenced parts when opening an assembly.
Is an SLDDRT file a SolidWorks 3D model?
No. An SLDDRT file is a SolidWorks drawing sheet format used when creating 2D drawings. It is different from an SLDPRT part or an SLDASM assembly and is not the 3D model itself. For viewing a design in a CAD viewer, request the corresponding model files.
Which formats can SolidWorks files be converted to?
The 3D-NativeCAD Converter in 3D-Tool Premium reliably converts native SolidWorks models to STEP, IGES, JT, SAT, and Parasolid X_T. For exchange with Designcenter (Siemens NX) and Designcenter Solid Edge, the Parasolid X_T format is specifically recommended. The target format depends on the recipient's CAD interface and how the exported geometry will be processed.