Vantis Core is the money layer of a vertical SaaS serving independent clinics. It handles plans, seats, proration, and tax across a dozen regions, and exposes a clean admin surface for non-technical account managers.
The problem
The original billing code was a tangle of if-statements around Stripe webhooks, and every new plan shape caused a weekend of firefighting.
What I built
A domain model that treats plans, entitlements, and usage as first-class objects, with an idempotent event pipeline in front of Stripe. Account managers get a focused admin UI instead of raw dashboards.
Outcome
New plan shapes now ship in an afternoon. No billing incidents in the six months since launch.