Mayo
Mayo is a fast, open-source (BSD-2-Clause) 3D CAD viewer and batch format converter built by Fougue on top of Open CASCADE Technology (OCCT) and Qt. It enables mechanical engineers and manufacturing teams to inspect STEP (AP203/AP214/AP242), IGES, BREP, DXF, STL, OBJ, glTF 2.0, VRML, and PLY assemblies with interactive XCAF product trees, real-time cross-section clipping planes, surface area/volume metrology, and command-line batch conversion.
Full Pricing Breakdown
Official software licensing terms, volume discounts, educational exemptions, and renewal fees vary significantly across countries, exchange rates, and regional authorized resellers. Click below to verify real-time terms directly on the vendor portal.
Key Capabilities
3D B-Rep & Assembly Inspection
Format Conversion & CLI
Technical Audit
Compatibility & Interoperability
Trust & Support
The Pros
- Lightweight (~30 MB) native C++/Qt application that opens large STEP assemblies in seconds without launching a full CAD suite.
- Includes a built-in exploded-view slider and interactive clipping planes for inspecting internal bores and mating clearances.
- Converts bi-directionally between STEP/IGES and web/mesh formats (glTF, GLB, OBJ, STL) with user-controlled tessellation deflection.
- Supports headless command-line execution (`mayo-conv`) for automated server or CI/CD CAD conversion pipelines.
- Permissive BSD-2-Clause open-source license allows unrestricted commercial deployment inside corporate networks.
The Cons
- Read-only viewer and converter; cannot edit sketch geometry or modify parametric feature trees.
- Does not natively open proprietary closed formats like SolidWorks (.SLDPRT) or Revit (.RVT).
- 2D DWG support is not included (supports DXF and 3D STEP/IGES/Mesh formats).
- Point-to-point linear dimension markup tools are simpler than paid commercial viewers like Glovius.
- macOS builds require manual compilation from source or community packaging compared to official Windows/Linux installers.
CADGuide Verdict
Final Professional Conclusion
"Mayo is the best free, open-source desktop alternative to commercial CAD translators like CAD Exchanger for STEP/IGES-to-glTF/STL conversion and fast shop-floor assembly inspection."
Official & Product FAQ
Sourced from official vendor documentation, licensing terms, and product specifications
?What is Mayo used for?
According to official documentation on GitHub (fougue/mayo), Mayo is an open-source 3D CAD viewer and converter based on Open CASCADE and Qt, used to inspect and convert STEP, IGES, BREP, STL, OBJ, and glTF 3D files. See the Official Mayo Repository.
?How much does Mayo cost?
Mayo is 100% free and open-source software released under the permissive 2-Clause BSD License. It is free for both personal and commercial enterprise use.
?Which file formats can Mayo import and export?
Mayo imports STEP (AP203, AP214, AP242), IGES, Open CASCADE BREP, DXF, STL (ASCII/Binary), Wavefront OBJ, glTF 2.0 / GLB, VRML, PLY, and OFF, and exports to STEP, IGES, BREP, STL, OBJ, glTF/GLB, VRML, and PLY. Download installers from Mayo Releases.
?Can Mayo run from the command line for batch conversion?
Yes. Mayo includes a dedicated command-line interface that converts 3D CAD files in batch mode without opening a graphical window.
?What operating systems does Mayo support?
Mayo provides pre-built binaries for 64-bit Windows and Linux (AppImage), and builds cleanly on macOS via CMake.
?What are the best alternatives to Mayo?
Top alternatives include F3D (open-source VTK viewer), FreeCAD, CAD Exchanger, and Glovius.
