Server Actions in Next.js: When to Use Them

What Are Server Actions?

Server Actions are async functions that run on the server, callable directly from client components. Instead of creating API routes for every mutation, you write a function marked with use server:

Then call it from a form:

No fetch calls. No API route. No loading state management.

When Server Actions Shine

Simple forms and mutations. Contact forms, newsletter signups, like buttons. Server Actions eliminate boilerplate.

Progressive enhancement. Forms with Server Actions work without JavaScript. The browser submits normally, server handles it.

Colocated logic. Your mutation logic lives next to the component, not in a separate API directory.

When to Use API Routes Instead

Complex request/response patterns. Custom headers, streaming responses, specific HTTP status codes.

Webhook receivers. Third-party webhooks expect specific endpoint URLs and response formats.

Mobile app backends. If your API serves both web and mobile, traditional routes provide a clean interface.

File uploads with progress. Upload progress tracking is easier with fetch-based approaches.

Our Pattern

1. Form submission or simple mutation? Server Action
2. Called from outside this Next.js app? API Route
3. Needs streaming or custom HTTP semantics? API Route
4. Webhook or third-party callback? API Route
5. Everything else? Start with Server Action

In practice, about 70% of our mutations use Server Actions. The remaining 30% are API routes for webhooks and integrations.

Conclusion

Server Actions reduce boilerplate for common patterns. They complement API routes rather than replace them. Use the right tool for each job.