architecting-saas

Secure authentication in a Next.js SaaS application requires using validated user retrieval methods like getUser() instead of insecure session retrieval like getSession() in middleware. This approach prevents common AI errors related to missing or spoofed authentication checks.

Designing a multi-tenant database schema with Supabase involves using an account_id column combined with Row Level Security (RLS) for strict data isolation. This ensures users can only access data belonging to their specific tenant accounts.

To separate business logic from Server Actions in Next.js for testing, extract pure business logic into dedicated service layers. Keep Server Actions as thin wrappers for framework-specific concerns, ensuring your core logic remains fully unit-testable.

The getSession() method poses a security risk for SaaS authentication because it retrieves sessions insecurely without server-side validation. Using getUser() instead enforces strict validation, ensuring the authenticated user context is actively verified by Supabase.

You can build a multi-tenant project management tool using Next.js and Supabase by implementing secure authentication, defining shared account database schemas with RLS, and organizing business logic into testable service layers for maintainability.

Common architectural pitfalls when building SaaS apps with Next.js include using insecure session retrieval, missing multi-tenancy data isolation, and embedding untestable business logic directly within Server Actions instead of isolated service layers.