NextAuth v5 setup guide: authentication for your Next.js SaaS

NextAuth v5 is the authentication library used in CheapStack kits. Here's how it works.

Basic setup

NextAuth v5 uses a single configuration file that defines your auth providers and callbacks.

import NextAuth from "next-auth";

import GitHub from "next-auth/providers/github";

import Google from "next-auth/providers/google";

export const { handlers, signIn, signOut, auth } = NextAuth({

providers: [GitHub, Google],

callbacks: {

session({ session, user }) {

if (session.user) session.user.id = user.id;

return session;

},

},

});

Route handler

NextAuth v5 uses a catch-all route file for the API endpoints:

// app/api/auth/[...nextauth]/route.ts

import { handlers } from "@/lib/auth";

export const { GET, POST } = handlers;

Protecting pages

Use the auth() function in Server Components:

import { auth } from "@/lib/auth";

import { redirect } from "next/navigation";

export default async function DashboardPage() {

const session = await auth();

if (!session?.user) redirect("/auth/signin");

return

}

Available providers in CheapStack

The SaaS Starter ($49) includes GitHub and Google OAuth.

The SaaS Boilerplate ($59) includes GitHub, Google, Discord, email/password, and magic link authentication.

NextAuth vs alternatives

NextAuth v5 is the most widely used auth library for Next.js. It supports 80+ providers, has built-in database adapters for Drizzle and Prisma, and is maintained by the Next.js team via Auth.js.

Alternatives include Clerk (easier setup, more features, paid at scale), Better Auth (newer, TypeScript-first), and Supabase Auth (tightly integrated with Supabase).

About the author: Muhammad Akbar builds affordable developer tools at CheapStack and writes about bootstrapping products on realistic budgets.