SaaS Multi-Tenant Architecture

When to Use This Skill

The user is building a SaaS application where multiple customers share the same database
The user asks about tenant isolation, row-level security, or data leakage prevention
The user needs to scope every database query to a specific tenant without manual WHERE clauses
The user asks about shared-schema vs schema-per-tenant vs database-per-tenant tradeoffs
The user is implementing admin endpoints that must access data across tenants
The user needs to add tenant_id columns to an existing single-tenant application
The user asks about PostgreSQL RLS policies for tenant isolation
The user is building tenant-aware middleware in Express, Fastify, or Next.js API routes

Do NOT use this skill when:

The user is building a single-user application with no shared infrastructure
The user asks about authentication only without tenant scoping (use an auth skill instead)
The user needs general database schema design without multi-tenancy requirements