A software architecture where a single instance serves multiple isolated customers with separate data.
Multi-Tenancy is the architecture that makes SaaS economically viable. Instead of deploying a separate instance of your application for each customer, a single deployment serves all customers (tenants) while keeping their data logically isolated. This dramatically reduces infrastructure costs and operational complexity. The key challenge is ensuring strict data isolation -- Tenant A must never see Tenant B's data. This is typically achieved using Row-Level Security (RLS) in PostgreSQL, schema-per-tenant strategies, or application-level filtering. Multi-tenancy also involves tenant-specific configuration, feature flags, and usage-based billing.
Each request is tagged with a tenant identifier (from subdomain, JWT token, or API key).
Database queries are automatically scoped to the tenant using RLS policies or middleware filters.
Tenant-specific settings (branding, features, limits) are loaded from a configuration store.
Usage is tracked per tenant for billing, and resource limits prevent noisy-neighbor problems.
Any SaaS product where multiple companies use the same application with isolated data.
Products that can be customized and branded differently for each tenant.
Multi-vendor marketplaces where each seller has their own isolated storefront and inventory.
Knowing the definition is step one. Building it into your product is step two. That's where we come in.