Optitex 21 is professional-grade 2D/3D CAD software and is not available for free
Optitex 12 or 13 (released 2010–2015) can sometimes be found on archive.org or through second-hand license transfers. Legally, you can buy a used license from a company that upgraded, then transfer it via Optitex’s license transfer form. This is legal and often cheap ($200–500). optitex 21 free download link
Let me be direct: Here’s why: