Multi-tenancy looks simple at first.
You add an organization_id to your tables, check it in your queries, and move on.
The problem is that this puts a lot of responsibility on application code.
I wanted tenant isolation to be enforced at the database level too, so I used PostgreSQL Row Level Security (RLS).
The basic architecture is:
- Users belong to organizations
- Organization membership determines access
- Server-side authorization handles application permissions
- PostgreSQL RLS provides another layer of tenant isolation
- Roles such as Owner, Admin, and Member control what users can do
This also makes other parts of the application more interesting:
- Team invitations
- Organization switching
- API keys
- Usage limits
- Billing tied to organizations
The biggest lesson for me was that multi-tenancy isn’t really a single feature.
It’s an authorization model that needs to stay consistent across the application and database.
I built these patterns into a reusable B2B SaaS foundation because I got tired of rebuilding them for every project.
If you’re building a multi-tenant SaaS with Next.js and Supabase, I’ve put the full foundation here:
I’d be interested to hear how other Next.js developers approach tenant isolation. Do you rely mainly on application-level checks, RLS, or both?