Is there a free MLM software platform?

No real free option. $290 to $390/month is the production-ready floor.

We've yet to find a free MLM platform that's production-ready for any business handling real money. Open-source options exist but require significant DevOps work plus custom comp-plan code; the total cost in engineering time and operations exceeds what real cloud SaaS charges. The lowest real production tier is around $290 to $390 per month (CloudMLM entry tier or ARM MLM Cloud). Below that price point, vendors are either feature-stripped, unmaintained, or both.