Magento Open Source, what’s the catch at $0 license?

The catch is that “$0 license” isn’t the same as “$0 to operate.” Magento Open Source has the highest variable cost of the 5 platforms in the calculator. The numbers shift from license to dev + hosting:

• You self-host. $6k, $30k/yr depending on traffic. Cloudways, Sonassi, Hipex, JetRails are common. Cloudflare in front, redis cache, varnish, OpenSearch.
• You’re responsible for security patches. Magento ships ~3 critical security patches a year. If you’re late to apply them, you’re on the hit list of every Magento exploit kit. Auto-patching tooling exists (Magecheck, Sansec, MageReport) but a human still QAs each release.
• Extensions for B2B / RMA / segmentation are paid. Aheadworks, Amasty, Magenest each charge $200, $2,000 per extension, sometimes annual. Calculator allocates $5k, $8k for a typical extension stack, that’s already counted.
• No SLA support. You’re on Stack Overflow + your dev retainer. Most stores at $5M+ have an on-call freelancer or a 5-10 hour/month minimum retainer.
• Version upgrades require effort. Magento 2.4.4 → 2.4.6 → 2.4.7 → 2.4.9 each break some extensions. Plan for 1-2 weeks dev time per major version, ~once a year.

The break-even math: Magento Open Source is cheapest TCO when (a) GMV ≥ $1M (below this the dev cost doesn’t pay off vs a hosted SaaS), (b) you have B2B share < 50% (above this Adobe Commerce native B2B earns its license), and (c) you have access to a competent Magento dev (in-house, retainer, or freelance). Without the third, Magento Open Source becomes the most expensive platform on the calculator because dev cost spirals.