If you're building a product that multiple customers will use—each with their own data, users, and settings—you need multi-tenant architecture. Get it wrong, and you'll rebuild everything when you scale.
What Is Multi-Tenancy?
Multi-tenancy means one application serving many customers (tenants) from shared infrastructure. Each customer's data is isolated, but the codebase and resources are shared.
Think of it like an apartment building: everyone shares the structure, utilities, and common areas, but each unit is private and self-contained.
Why It Matters for Your Business
Cost efficiency — One system to maintain instead of deploying separate instances per customer. Your infrastructure costs grow linearly, not exponentially.
Faster onboarding — New customers provision instantly. No manual setup, no environment configuration.
Simplified updates — Deploy once, update everyone. No version fragmentation across customer installations.
Better resource utilisation — Quiet customers subsidise busy ones. You don't over-provision for peak usage per customer.
The Architecture Choices
Database per tenant — Complete isolation. Best for regulated industries or customers with strict data residency requirements. Most expensive to operate.
Schema per tenant — Shared database, separate schemas. Good balance of isolation and efficiency. Moderate complexity.
Shared tables with tenant IDs — All data in shared tables, filtered by tenant identifier. Most efficient but requires careful access control. Every query must include tenant context.
Security Considerations
Multi-tenancy done poorly is a data breach waiting to happen:
Query isolation — Every database query must filter by tenant. One missed filter exposes data to wrong customers.
Authentication boundaries — Users can only access their organisation's resources. Cross-tenant access requires explicit permissions.
API scoping — Tokens and keys are bound to organisations. Integrations can't accidentally read other tenants' data.
Audit logging — All access is logged with tenant context for compliance and debugging.
When to Choose Multi-Tenancy
Multi-tenant architecture makes sense when:
- You're building a SaaS product with many customers
- Customer requirements are relatively similar
- You need to scale without proportional infrastructure costs
- Rapid deployment of new customers is a priority
Building a SaaS platform? Contact us to discuss how multi-tenant architecture can support your growth.