Next.js Server Actions vs API Routes: When to Use Each

Next.js 15 gives you two ways to handle server-side logic: Server Actions and API Routes. Both work, but they're designed for different use cases. Choosing the wrong one leads to unnecessary complexity or missing features.

This guide teaches you when to use each approach.

Understanding the Differences

Server Actions

Server Actions are async functions that run on the server and are called directly from components.

// app/actions.ts ' use server '

export async function createPost ( formData : FormData ) { const title = formData . get ( ' title ' ) as string const content = formData . get ( ' content ' ) as string

const { data , error } = await supabase . from ( ' posts ' ) .…