Next.js for SaaS: Architecture That Scales

Building SaaS with Next.js: The Sprint Forge Approach

Next.js has become our go-to framework for SaaS applications. With the App Router, React Server Components, and excellent TypeScript support, it provides a solid foundation for building scalable software.

Multi-Tenancy Architecture

Every SaaS needs to handle multiple customers (tenants). We typically implement one of three patterns:

1. Database per Tenant

Complete data isolation

Higher infrastructure costs

Best for enterprise clients with compliance requirements

2. Schema per Tenant

Good isolation with shared infrastructure

More complex migrations

Works well for mid-market SaaS

3. Shared Database with Tenant ID

Simplest to implement

Requires careful query design

Our default choice for most applications

Authentication Pattern

We use a combination of:

**NextAuth.js** (Auth.js) for session management

**JWT tokens** for API authentication

**RBAC** (Role-Based Access Control) with middleware enforcement

API Layer Structure

Organize API routes by domain, not by HTTP method:

app/api/

├── users/

│ ├── route.ts # GET all, POST create

│ └── [id]/

│ └── route.ts # GET one, PATCH update, DELETE

├── organizations/

│ └── ...

└── billing/

└── ...

Database Considerations

**PostgreSQL** for most use cases—battle-tested and reliable

**Prisma** as ORM for type-safe database access

Connection pooling with **PgBouncer** for scale

Read replicas for heavy read workloads

Caching Strategy

**ISR** (Incremental Static Regeneration) for semi-static content

**Redis** for session storage and frequently accessed data

**React Query** for client-side cache management

Conclusion

A well-architected Next.js SaaS application can scale to millions of users. The key is making good foundational decisions about multi-tenancy, authentication, and data access patterns early.