Architecture Patterns for Multi-Tenant SaaS

Multi-tenancy is one of the most important architectural decisions in SaaS development. Get it right, and scaling is straightforward. Get it wrong, and you'll fight your database for years.

The Three Approaches

1. Separate Database: Each tenant gets their own database. Maximum isolation, easier backup/restore per tenant, but harder to manage at scale.

2. Shared Database, Separate Schema: Each tenant has their own schema in the same database. Good balance of isolation and operational simplicity.

3. Shared Database, Shared Schema: All tenants share the same tables, with a tenant_id column. Most operationally efficient but requires careful query scoping.

Choosing the Right Approach

For most B2B SaaS products, shared database with tenant_id column is the right starting point. It's simple, performant, and easy to reason about. You can always add isolation later for specific tenants that need it.