system-type-multi-tenant-saas
Installation
SKILL.md
System Type: Multi-Tenant SaaS
Patterns, failure modes, and anti-patterns for multi-tenant software-as-a-service platforms.
1. Isolation Models
Every multi-tenant system lives on a spectrum between full sharing and full isolation. The choice is not one-time — most mature SaaS platforms mix models across their stack.
The Spectrum
| Model | Description | Cost per tenant | Isolation strength | Operational complexity |
|---|---|---|---|---|
| Shared everything | Single DB, single schema, tenant_id column on every row |
Lowest | Weakest — one bad query away from data leakage | Lowest until it isn't |
| Shared compute, separate data | Shared application tier, separate database or schema per tenant | Medium | Strong data isolation, shared failure domain for compute | Medium — schema migrations multiply |
| Fully siloed | Dedicated infrastructure per tenant (DB, compute, sometimes network) | Highest | Strongest — blast radius limited to one tenant | Highest — you're running N deployments |