Next.js has always been known for making web development easier and faster, especially for server-side work. For a long time, developers have used API Routes (also known as Route Handlers) to handle backend logic like REST APIs, form submissions, webhooks, and more.
But now, with the newer versions of Next.js (version 14 and 15, which use the App Router), there’s a new and better way of doing things called Server Actions (sometimes also called Server Functions).
This new feature is changing the way we write and organize backend code. It allows you to keep your server logic closer to your components, write less code, and even get better performance and security in many cases.
In this blog, we will explore:
-
What Server Actions (or Server Functions) are
-
How are they different from API Routes
- When to use each
- How to implement Server Actions (with simple examples)
-
Important security and performance tips
-
What this means for the future of API Routes
What Are Server Actions / Server Functions?
Let’s understand this in simple terms.
Server Actions are async functions that run directly on the server. You can mark them with a special keyword — "use server" — and Next.js will know that this function should only run on the server side.
Here’s what makes them special:
-
You can call them directly from your React components (especially Server Components).
-
You can even use them inside Client Components (as long as they are imported from files with "use server" at the top).
- They are great for doing tasks like saving data, submitting forms, or updating something on the server.
- Behind the scenes, they work using POST requests only.
-
The data you pass to them and get back must be serializable (which means it can be safely turned into JSON and sent over the network).
In short, Server Actions let you handle your backend logic without creating a separate API endpoint.
API Routes (Route Handlers)
Before we compare, let’s quickly recall what API Routes do.
API Routes are special files that let you create REST-style endpoints in your Next.js app. You put them under folders like app/api/.../route.js or route.ts, and each one can handle different HTTP methods like GET, POST, PUT, or DELETE.
They are perfect when:
-
You want to create endpoints that other apps or systems can call.
-
You are building a public API.
- You have complex routing or multiple methods in one place.
- You need to control things like headers, authentication tokens, or CORS.
They keep the client-side and server-side code separate, which makes it easier to manage large or complex applications.
Server Actions vs API Routes: Which to Use When
When to Use Each
Use Server Actions when:
-
You are submitting a form from a component.
-
You want to update data without creating a new API file.
- Your logic is directly related to the component UI.
- You want automatic revalidation or caching features.
Use API Routes when:
-
You need to expose endpoints to external systems or third parties.
-
You need to handle multiple HTTP methods (GET, POST, etc.).
- You need to work with headers, tokens, or handle CORS.
- You are working on a large enterprise-level app or microservice.
How to Use Server Actions: Step-by-Step Examples
Example 1: Creating a Post with a Form
// app/actions.ts
'use server'
import { revalidatePath } from 'next/cache'
import { redirect } from 'next/navigation'
export async function createPostAction(formData: FormData) {
const title = formData.get('title')
const content = formData.get('content')
if (!title || !content) {
throw new Error('Missing fields')
}
await db.posts.create({ title, content })
revalidatePath('/posts')
redirect('/posts')
}// app/(pages)/new-post/page.tsx
import { createPostAction } from '@/app/actions'
export default function NewPostPage() {
return (
<form action={createPostAction}>
<input name="title" placeholder="Title" />
<textarea name="content" placeholder="Content"></textarea>
<button type="submit">Create Post</button>
</form>
)
}What’s happening:
This lets users submit a new post directly from the component. The createPostAction function handles everything; no need for a separate API route.
Example 2: Sending Feedback from a Client Component
// app/actions.ts
'use server'
export async function sendFeedback(formData: FormData) {
const feedback = formData.get('feedback')
return { status: 'ok' }
}// app/components/FeedbackForm.tsx
'use client'
import { useFormState } from 'react-dom'
import { sendFeedback } from '@/app/actions'
export function FeedbackForm() {
const [state, action, pending] = useFormState(sendFeedback, { feedback: '' })
return (
<form action={action}>
<textarea name="feedback" />
<button type="submit">
{pending ? 'Sending...' : 'Send Feedback'}
</button>
</form>
)
}What’s happening:
This example shows how Client Components can use Server Actions to handle logic like sending feedback without writing a full backend API.
Example 3: Using Cookies, Redirects & Revalidation
// app/actions.ts
'use server'
import { cookies } from 'next/headers'
import { revalidatePath } from 'next/cache'
import { redirect } from 'next/navigation'
export async function loginUser(formData: FormData) {
const username = formData.get('username')
const password = formData.get('password')
const cookieStore = cookies()
cookieStore.set('token', 'some-jwt-token', { httpOnly: true, path: '/' })
revalidatePath('/dashboard')
redirect('/dashboard')
}What’s happening:
After the user logs in, this Server Action sets a cookie, updates the cache, and redirects the user — all in one place, clean and simple.
Security, Limitations, and Things to Keep in Mind
Even though Server Actions make things easier, you should still follow best practices:
1. Always validate input – Don’t trust form data blindly. Check for missing or invalid values.
2. Understand serialization – Only send simple data (like strings, numbers, or plain objects).
3. CSRF protection – Server Actions already enforce POST and same-origin rules, but adding extra validation is still good.
4. Don’t use them for fetching data – Use them for updates (mutations). For fetching, rely on Server Components or API Routes.
5. Error handling – Handle all possible errors gracefully to avoid breaking the UI.
6. Caching and revalidation – Use functions like revalidatePath or revalidateTag to keep your pages up to date.
Real-World Use Cases
-
Auth0 has shown how Server Actions can securely call external APIs without needing extra route handlers.
-
GitHub developers mentioned that Server Actions helped them simplify code and reduce time, though they still use API Routes for large-scale fetching.
- Medium discussions point out that Server Actions improve developer productivity but should be used wisely to avoid overuse.
What’s Coming Next
With Next.js version 15+, we can expect:
-
Even faster caching and parallel execution
-
Better TypeScript safety
- Improved developer tools
- Stronger integration with edge runtimes and serverless functions
So, Server Actions are not replacing API Routes entirely — instead, they’re making small-scale backend logic simpler and faster, while API Routes will continue handling large or public APIs.
Conclusion
Server Actions mark a big change in how we build full-stack React and Next.js apps. They help bring server logic closer to the UI, cut down on boilerplate, and make small backend tasks much easier and faster.
But remember — they don’t replace API Routes completely.
Both have their place:
-
Use Server Actions for small, internal logic and form submissions.
-
Use API Routes for larger systems, integrations, and public APIs.
According to the Vercel 2025 Next.js Developer Survey, over 63% of developers are already using Server Actions in real projects.
So if you are working with Next.js v14 or v15, start experimenting with Server Actions — you will find them clean, efficient, and future-ready.
And keep using API Routes wherever you need full control, external exposure, or complex routing.
At Sparkle Web, our full-stack experts specialize in Next.js, React, and serverless architecture. We build scalable and high-performance web solutions powered by the latest frameworks like Next.js 15 and Server Actions. Want to upgrade your app to the future-ready Next.js stack? Let’s make it happen together. Connect with us today.
Vaishali Gaudani
Skilled React.js Developer with 3+ years of experience in creating dynamic, scalable, and user-friendly web applications. Dedicated to delivering high-quality solutions through innovative thinking and technical expertise.
Reply