What it means
Most SaaS products are multi-tenant. Instead of running a separate copy of the software for each customer, one application serves everyone, and every record is tagged with the tenant it belongs to. Users only ever see their own tenant's data.
Separation can be done in the application, with separate database schemas or with separate databases, each with different trade-offs in cost and isolation.
Why it matters for a business
Multi-tenancy keeps hosting and maintenance costs low as a product grows, since one update reaches every customer. Getting data separation right from the start is essential, because leaking one customer's data to another is one of the worst failures a SaaS can have.
A business example
Things to watch
-
Enforce tenant separation on the server for every request.
-
Test that one tenant can never see another's data.
-
Plan how large tenants affect shared performance.
-
Decide early how tenants can export or delete their data.