Multi-Tenant SaaS Architecture with Next.js: Shared DB vs. Database-per-Tenant
Choosing the wrong database isolation strategy at MVP stage can force a 6-month complete rewrite as your customer base expands. Here is our decision framework for building scalable multi-tenant SaaS products on Next.js and PostgreSQL.
The Three Multi-Tenancy Architecture Patterns
When designing a B2B SaaS platform, engineering teams must evaluate three fundamental data isolation paradigms:
1. Shared Database with Row-Level Security (RLS)
All tenants share a single PostgreSQL database instance. Isolation is enforced at the database engine level via PostgreSQL Row Level Security policies and session tenant context variables.
2. Schema-per-Tenant
One database cluster where each customer has their own dedicated SQL schema. Offers logical separation while keeping connection pooling consolidated.
3. Database-per-Tenant (Physical Isolation)
Each organization receives an isolated database instance or serverless branch (e.g. AWS Aurora / Neon). Zero noisy neighbor issues and independent backup snapshots.
Implementing PostgreSQL RLS in Next.js Server Components
To guarantee zero cross-tenant data leakage in Next.js App Router, we enforce RLS on every transaction by setting a session-scoped tenant ID extracted from verified JWT claims:
-- Enable Row Level Security
ALTER TABLE organizations ENABLE ROW LEVEL SECURITY;
ALTER TABLE projects ENABLE ROW LEVEL SECURITY;
-- Define RLS Policy enforcing tenant boundary
CREATE POLICY tenant_isolation_policy ON projects
FOR ALL
USING (organization_id = NULLIF(current_setting('app.current_org_id', true), '')::uuid);Planning a Multi-Tenant SaaS Platform?
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