Server Actions vs API Routes in Next.js 15 App Router

I've had similar concerns. Personally, if it's a CRUD with heavy form submissions, I recommend server actions. Server actions handle form data directly and make cache invalidation easy with revalidatePath, which really boosts productivity. Authentication can be handled in middleware, and error handling within server actions is possible using try-catch. However, if you have complex APIs or extensive external integrations, API routes might be a better choice.

I've used server actions in production, and they worked better than expected. Security wasn't a big concern since they only run on the server, and Next.js handles CSRF automatically, which was convenient. For error handling, throwing an error in a server action lets you catch it on the client side. Authentication worked well when combined with Supabase or Next-Auth. However, as the project scales, separating into API routes proved better for maintainability.

I actually prefer API routes. Server actions are convenient, but debugging is difficult, and tracking error logs in particular has been inconvenient for me. With API routes, everything is managed in a RESTful way, it's easy to test with Postman, and authentication middleware can be cleanly applied in route.ts. For CRUD operations, API routes are actually more systematic and scalable.

From someone who has used both, I'd advise that starting with server actions for rapid development and switching to API routes when needed is a solid strategy. In Next.js 15, server actions aren't included in the client bundle, and handling authentication directly on the server with the auth() function poses almost no security issues. For error handling, combining formState with toasts can create a great user experience.

I insisted on using API routes for authentication handling, but it turns out server actions are perfectly capable as well. However, for JWT token management or refresh logic, API routes are more intuitive. Server actions shine when processing data on a per-page basis, while API routes are better for common logic called from multiple clients. Using a mix of both is also an option.

I'm struggling with the same issue. How do you handle file uploads or image processing when using server actions? With API routes, it's easy to use middleware like multer, but I'm worried server actions might have limitations. I'd really appreciate it if you could share your experiences!

The debate between server actions and API routes ultimately seems to have no definitive answer. I think server actions are better for small projects, while API routes are preferable for team-based work or when there's heavy integration with external APIs. In Next.js 15, combining server actions with form actions significantly reduces code lines, boosting productivity, while API routes have strengths in testing and documentation. In practice, the trend is usually to use a mix of both.