Glossary · saas
Multi-Tenant
Definition
Multi-tenant is a SaaS architecture where one software instance serves many customers (tenants). Each tenant's data is logically isolated — invisible to other tenants. It's the foundation of modern SaaS like Salesforce, Slack, Notion, Stripe.
Detailed explanation
3 isolation strategies: (1) Database-per-tenant (most isolated, expensive, regulation-heavy sectors), (2) Schema-per-tenant (PostgreSQL schema), (3) Shared schema + tenant_id (tenant_id on every row, most common + economical).
Vs single-tenant: single-tenant gives each customer its own infrastructure (banking + critical enterprise); multi-tenant is one shared infrastructure. Cost: multi-tenant 10-100x cheaper; isolation: single-tenant stronger.
Design choices: tenant_id on every table + RLS (Row-Level Security), authentication (every user belongs to a tenant), billing (Stripe customer per tenant), feature flags (per-tenant feature toggles).
Pitfalls: forgetting tenant_id (data leak — nightmare), noisy neighbor (one tenant strains DB), GDPR/KVKK data export (per-tenant export hard), backup + restore per tenant.
Use cases
→B2B SaaS products
→Marketplace (each seller a tenant)
→Multi-brand e-commerce
→Education platform (each school a tenant)
→White-label solutions
Pros
- +10-100x lower cost
- +Single infra = single deploy + single upgrade
- +Easy horizontal scaling
- +Fast onboarding (new tenant = signup)
Cons
- −Tenant_id leak risk (data breach)
- −Noisy neighbor (one tenant strains DB)
- −Per-tenant data export is hard
- −Compliance + audit log complex
Related terms
Related services
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