Design an extensible permissions engine for multi-tenant creator sites

Design an extensible permissions engine for multi-tenant creator sites targets a $3.0B = 1,000,000 SaaS/creator platforms × $3K ACV total addressable market with medium saturation and a year-over-year growth rate of 12% CAGR — market growth for identity and authorization tooling driven by SaaS and creator economy expansion (industry syntheses from Gartner and IDC trends).

Key trends driving demand: Creator economy growth — more creators are launching subscription and course sites which increases demand for multi-tenant authorization and billing integrations.; Shift to composable architecture — teams prefer embedding specialized services (auth, payments, subscriptions) which lowers friction for an embeddable permissions engine.; Rise of policy-as-code and relationship-based auth — new architectures make it feasible to offer robust authorization without years of custom engineering.; Demand for low-friction UX for non-technical users — creators and small teams expect simple admin tools and prebuilt roles, creating an opportunity for verticalized solutions..