A Practical Guide to Server Actions in Next.js

Introduction

Server Actions are one of the most impactful additions to Next.js in recent years and also one of the most misunderstood.

They promise:

• Fewer API routes
• Less boilerplate
• Better security by default

But in real-world applications, misusing Server Actions can quickly lead to poor structure, tight coupling, and hard-to-test code.

This article is not a basic introduction.
It’s a practical guide based on how I actually use Server Actions in production Next.js apps.

What Server Actions Actually Are (Without the Marketing)

At their core, Server Actions are just async functions that run on the server and can be invoked from the client.

"use server";
 
export async function createPost(formData: FormData) {
  // runs on the server
}

What makes them powerful is:

• They never ship to the browser
• They can directly access databases, secrets, and internal services
• They integrate seamlessly with React forms and transitions

What makes them dangerous:

• They can blur boundaries if you’re not disciplined

When I Use Server Actions

I use Server Actions for mutations that are tightly coupled to UI interactions.

Good use cases:

• Form submissions
• Button-triggered mutations
• Simple CRUD operations
• Authenticated user actions

Example: Creating a comment.

"use server";
 
import { db } from "@/lib/db";
import { auth } from "@/lib/auth";
 
export async function createComment(formData: FormData) {
  const user = await auth();
  if (!user) throw new Error("Unauthorized");
 
  const content = formData.get("content") as string;
 
  await db.comment.create({
    data: {
      content,
      userId: user.id,
    },
  });
}

When I Do Not Use Server Actions

I do not use Server Actions when:

• The logic is shared across multiple clients (mobile, external APIs)
• I need versioning
• I need public endpoints
• The logic is complex business logic

Server Actions are not a backend replacement.

Folder Structure That Scales

app/
  actions/
    comment.actions.ts
    post.actions.ts
  components/

Handling Errors Properly

"use server";
 
export async function updateProfile(data: ProfileInput) {
  if (!data.name) {
    throw new Error("Name is required");
  }
}

Security Considerations

Always:

• Validate authentication
• Validate input
• Never trust client-provided data

Server Actions vs API Routes

Final Thoughts

Server Actions are powerful, but only when used intentionally.

UI-driven mutations → Server Actions
Everything else → APIs or services

Happy building 👋