Building Enterprise-Grade Access Control in Next.js 16

As SaaS applications scale, managing multiple user roles and permissions becomes essential. This guide provides production-ready code for implementing Role-Based Access Control in Next.js 16 using Auth.js v5 and Prisma, covering middleware-based page protection, API route guarding, and conditional UI rendering. By following these patterns, developers can create scalable, secure authentication systems that grow with their applications.