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Mayo vs CAD Assistant: catalog facts
Mayo	CAD Assistant
Free Free and open source.	Free Free for personal and commercial use.
Windows, macOS, Linux	macOS, Android
Converts between STEP, IGES, STL and other CAD formats Clip planes, exploded views and measurement	Opens STEP, IGES and other CAD formats Converts between 3D formats
A viewer and converter, not a modelling tool	Viewer and converter only, not a modelling tool Closed source despite being built on the open OCCT kernel
Downloadable app	Downloadable app
Open source	Closed source
License not stated	License not stated
No account needed	Not stated if an account is needed
Works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked October 1, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.