Modern Next.js applications can have large codebases operating across multiple environments, including client components running in the browser, Server Actions executing on the server, and more. As applications become more complex, ensuring users can access only authorized data and actions becomes paramount. To that end, Next.js equips developers with tools to maintain data security. Developers can centralize authentication and authorization checks by integrating a Data Access Layer (DAL). In this blog post, we'll introduce the concept of a DAL and use it to implement a fine-grained authorization model within a Next.js application. Link to heading Client-side vs. server-side code in Next.js Link to heading Confidential vs. public environments Web applications typically run in two different environments: a confidential server environment and a public environment.…