Glossary
What Is Multi-Tenant SaaS?
Multi-tenant SaaS is a software architecture where one application serves many customers (tenants), with each customer's data fully isolated from others.
In a multi-tenant SaaS architecture, every customer uses the same application — but they can't see each other's data.
Why it matters for founders:
- You maintain one codebase instead of one per customer
- You deploy updates once, all customers get them
- Customers can't accidentally access each other's data
How data isolation works:
The most robust approach is Row-Level Security (RLS) via Postgres. Every row has a tenant_id column. RLS policies enforce that users can only query rows where tenant_id matches their session.
Implementation patterns:
- Row-Level Security — Best for most SaaS MVPs
- Schema-per-tenant — More isolation, more complexity
- Database-per-tenant — Maximum isolation, enterprise-scale cost
Related Terms