Native CAD interfaces
Direct support for the CAD formats listed here.
Autodesk Viewer
Open Inventor, Navisworks, and Revit files
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The 3D-Tool Viewer opens Autodesk Inventor, Navisworks, and Revit files without Autodesk software.
The 3D-NativeCAD Converter converts Autodesk 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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Open IPT, NWD, and RVT Files
Whether it's an IPT or IAM part from Inventor, an NWD coordination model from Autodesk Navisworks, or an RVT project from Autodesk Revit - these files often reach people who don't run that particular Autodesk product themselves, such as a supplier, a site manager, or a colleague in another department. The 3D-Tool Viewer opens all three formats directly.
Unlike plain online viewers, the 3D-NativeCAD Converter also turns Inventor, Navisworks, and Revit models into STEP and other common exchange formats - for example to continue working in a mechanical CAD system outside the Autodesk ecosystem.
What are Inventor, Navisworks, and Revit files?
What are IAM and IPT files?
Files with the IAM and IPT file extensions are native 3D files from Autodesk Inventor CAD/CAM software. IPT is the part file format and contains 3D geometry and, in some cases, Product Manufacturing Information (PMI). IAM is the assembly file format and is linked to at least one, but usually several, IPT files and often additional IAM files.
What are NWD files?
Files with the NWD file extension are published projects from Autodesk Navisworks CAD software. They contain all 3D models and project-related data from a Navisworks project in a single compressed file.
What are RVT and RFA files?
RVT and RFA files are Autodesk Revit formats for BIM projects (Building Information Modeling). RVT files (Revit project files) contain the entire 3D model of a project, while RFA files (Revit families) contain individual, reusable components such as doors, windows, or furniture.
Inventor, Navisworks, and Revit Versions
IAM and IPT Versions
Inventor 1 was released in 1999, and through Inventor 11 the versions were simply numbered. Since 2007, versions have been named using the year after the release year; for example, the version released in 2024 is called Inventor 2025. File versions created with newer releases cannot be opened with older releases.
NWD Versions
All Navisworks versions, such as Navisworks 2025, use the NWD format. When creating an NWD file, you can choose to save it in an older version. Through Navisworks 2015, this was necessary if a user of an older version needed to open the file. Since 2016, NWD files have been backward compatible. You can therefore open a Navisworks 2025 NWD file with Navisworks 2016.
RVT and RFA Versions
Revit version names are based on the release year, for example Revit 2025. Revit RVT and RFA files are neither backward nor forward compatible. Older files must be updated before they can be opened in a new version, which makes them inaccessible in the older version.
Additional native Autodesk file formats
- idw Native 2D drawing from Inventor, derived from IPT or IAM. Can only be opened in Inventor or Inventor View.
- dwg Native 2D drawing from AutoCAD. Because of the close relationship, it can be used in AutoCAD and Inventor. However, a DWG created with Inventor can only be modified in Inventor; a DWG created with AutoCAD can only be modified in AutoCAD.
- dxf The 2D DXF format was developed because early AutoCAD versions on Windows, MacOS, and Linux required different DWG data. The DXF format was later retained because it proved useful for exchange with other CAD programs. However, compared with DWG, a number of CAD functions are lost.
- nwf Native Navisworks assembly files. An NWF file contains links to the original native files as well as Navisworks-specific data, such as markups. No model geometry is stored in this file format, so an NWF file is significantly smaller than an NWD file.
How do I open Inventor, Navisworks, and Revit files?
IPT and IAM files are typically opened with an Inventor installation. Alternatively, CAD/CAM software with an Inventor interface, such as Designcenter (Siemens NX), can open these files. Inventor is free to use in read-only mode.
Besides a commercial Navisworks installation, the free Navisworks Freedom viewer opens NWD files. Like Inventor, Revit can be used free of charge in Viewer Mode to view RVT and RFA files.
Autodesk now also offers a web viewer for Inventor, Navisworks, and Revit models. Using the viewer requires registration with Autodesk.
The 3D-Tool CAD Viewer opens IPT, IAM, NWD, RVT, and RFA files and combines easy operation with many measurement and analysis tools. 3D-Tool can be tested free of charge for 14 days.
How do I convert Inventor, Navisworks, and Revit files?
Convert IPT, IAM, NWD, RVT, and RFA files to STEP with a 3D converter.
The 3D-NativeCAD Converter in 3D-Tool Premium reliably converts these formats and models from many other CAD systems into common 3D exchange formats. Available target formats are STEP, IGES, JT, SAT, and Parasolid X_T. Whether conversion is possible depends on the geometry contained in the file. Pure mesh data is not reconstructed as exact CAD surfaces.
Without a converter or CAD software with the appropriate interfaces, the creator must export the design to a common 3D exchange format, such as STEP.
Test the Inventor, Navisworks, and Revit viewer and converter for free
3D-Tool is a CAD Viewer with many native CAD interfaces, including Inventor, Navisworks, and Revit. It provides professional measurement tools, draft analysis, and wall thickness analysis.
- Open IPT, IAM, NWD, RVT, and RFA files, add dimensions and comments, and publish them for the 3D-Tool Free Viewer or as 3D PDF
- Open IPT, IAM, NWD, RVT, and RFA files and save them as STL, 3DS, PLY, WRL, or OBJ
- Convert IPT, IAM, NWD, RVT, and RFA files to STEP, IGES, SAT, X_T, and JT
- Convert Inventor, Navisworks, and Revit models to 3D product visualizations such as 3D-HTML, FBX, 3MF, and glTF
Free, no-obligation 14-day trial with all features, the Autodesk interfaces, and the 3D-NativeCAD Converter. The trial key activates all 3D interfaces, including CATIA, Designcenter (Siemens NX), SolidWorks, Creo, STEP, and SAT.
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Frequently Asked Questions (FAQ)
What is the difference between IPT and IAM files?
IPT is Inventor's part format, containing 3D geometry and sometimes PMI. IAM is the assembly format, linked to at least one IPT file and often further IAM files. When sharing an Inventor assembly, include the referenced part files and any subassemblies. The IAM file describes the assembly but does not replace the separate files needed to load its components.
What do RVT and RFA files contain?
RVT files (Revit project files) contain the entire 3D model of a BIM project. RFA files (Revit families) contain individual, reusable components such as doors, windows, or furniture. The distinction helps when requesting data: an RVT file represents the project, whereas an RFA file supplies a family that can be used within a project. Both are native Revit formats.
Are NWD files backward compatible with older Navisworks versions?
Yes, since Navisworks 2016. You can also open an NWD file from a newer version such as Navisworks 2025 with Navisworks 2016. Before that, the NWD file had to be explicitly saved in an older version. When exchanging files with older installations, clarify in advance which Navisworks version the recipient uses and which file format is required.
How can I open RVT and RFA files without Revit?
In the free 14-day trial, you can try the functions with your own Revit files.
Which formats can Inventor, Navisworks, and Revit files be converted to?
The 3D-NativeCAD Converter in 3D-Tool Premium converts IPT, IAM, NWD, RVT, and RFA models reliably into STEP, IGES, SAT, and Parasolid X_T, plus visualization formats such as STL, OBJ, 3DS, PLY, 3D-PDF, 3D-HTML, FBX, 3MF, and glTF. The available conversion depends on the geometry contained in the source model; mesh data cannot be reconstructed as exact CAD surfaces by 3D-Tool.