Multi-tenancy in Laravel starts with a clear isolation model. Most B2B SaaS uses shared database with organization_id on every tenant-owned row — enforced by global scopes and middleware.
Isolation options
- Shared schema + scoped queries (default)
- Database per tenant (enterprise isolation)
- Hybrid for VIP tenants
- Custom domains with tenant resolution
Test tenant isolation in CI — IDOR bugs are the highest-risk SaaS vulnerability.