Backend Developer — White-Label Multi-Tenant Ordering Platform (API/Platform Logic)

We run a white-label, multi-brand ordering platform (marketplace model). Our frontend — four CRMs including a customer storefront — is built in-house and partly done. We need a backend developer to own all server-side logic and APIs. No UI work. You'll build the multi-tenant engine (tenant_id scoping + row-level security, domain→brand resolver, per-tenant branding, feature flags), auth & RBAC across roles with impersonation, and the real-time order pipeline (state machine + live queue via WebSockets/SSE, customer tracking). On payments, you'll generalize our existing Stripe Connect split-payout behind a provider interface — refunds, webhooks, idempotency — then add more APMs later. You'll also build POS adapters (Square/Toast/Lightspeed/Clover + Deliverect/Otter) and the APIs powering all four CRMs, from a mostly greenfield Platform Owner admin to the customer checkout flow. Must have: multi-tenant + RLS experience, Stripe Connect/marketplace payouts, webhook-driven and real-time flows, third-party integration adapters, Postgres. Clean, documented, testable code with a documented API contract (OpenAPI/GraphQL) so our frontend integrates cleanly. To apply, share relevant multi-tenant / marketplace-payment / real-time backend work, your preferred stack, and availability.