Multi-Tenant Architecture: A Practical Guide for SaaS Developers

What is Multi-Tenancy?

Multi-tenancy is an architecture where a single instance of software serves multiple customers (tenants). Each tenant's data is isolated and invisible to other tenants, even though they share the same application and database infrastructure.

In the context of SaaS, each organization is a tenant.

Approaches to Multi-Tenancy

1. Database-per-Tenant

Each organization gets its own database. Maximum isolation, but complex to manage at scale.

2. Schema-per-Tenant

Shared database, separate schemas. Good isolation with easier management.

3. Shared Database with Row-Level Isolation

All tenants share tables, with an organizationId column on every row. This is the most common approach for SaaS applications and what ShipKit uses.

How ShipKit Implements Multi-Tenancy

ShipKit uses shared-database multi-tenancy with Prisma ORM. Every organization-scoped model includes an organizationId field, and all queries are automatically scoped to the current user's active organization.

Key Components

• Organization Model: Full CRUD with settings, secrets, and feature flags
• Membership Model: Links users to organizations with roles and permissions
• Middleware: Automatically resolves the current organization from the session
• Data Isolation: All queries are scoped — no accidental cross-tenant data leaks

Custom Roles & Permissions

ShipKit supports custom roles per organization. Each role has a set of granular permissions, allowing fine-grained access control:

• Organization-level permissions (manage members, billing, settings)
• Resource-level permissions (create, read, update, delete)
• Feature-level permissions (access to specific modules)

Best Practices

1. Always scope queries: Never fetch data without an organization filter
2. Test isolation: Write tests that verify one tenant cannot access another's data
3. Audit logging: Track all actions with the organization context
4. Rate limit per tenant: Prevent one tenant from consuming all resources

Conclusion

Multi-tenancy is a fundamental requirement for SaaS applications. Getting it right from the start saves you from painful refactors later. ShipKit provides a battle-tested implementation so you can focus on building features, not infrastructure.