Designing multi-tenant SaaS software demands strategic choices regarding data isolation, tenant routing, and resource management. Whether serving SMB clients or Fortune 500 enterprises with strict data sovereignty mandates, selecting the correct multi-tenancy model governs system scalability and compliance.
1. The 3 Tenant Isolation Strategies
- Shared Database, Shared Schema: Uses a 'tenant_id' column on all tables with PostgreSQL Row-Level Security (RLS). Maximum cost efficiency for high-density B2B SaaS.
- Shared Database, Separate Schema: Isolates each tenant into dedicated database schemas. Excellent balance of data privacy and infrastructure overhead.
- Database Per Tenant: Completely isolated database instances per enterprise tenant. Required for strict HIPAA, GDPR, and SOC2 compliance.
2. Next.js Subdomain & Custom Domain Tenant Routing
Edge proxy middleware intercepts incoming requests to 'tenant.yourdomain.com' or custom domains, injecting the resolved 'tenantId' into request context for downstream API rendering.