Migrating from Auth.js to Better Auth

Create Better Auth Instance

Before starting the migration process, set up Better Auth in your project. Follow the installation guide to get started.

For example, if you use the GitHub OAuth provider, here is a comparison of the auth.ts file.

import NextAuth from "next-auth"
import GitHub from "next-auth/providers/github"
  
export const { handlers, signIn, signOut, auth } = NextAuth({
  providers: [GitHub],
})

import { betterAuth } from "better-auth";

export const auth = betterAuth({
  socialProviders: { 
    github: { 
      clientId: process.env.GITHUB_CLIENT_ID!, 
      clientSecret: process.env.GITHUB_CLIENT_SECRET!, 
    }, 
  }, 
})

Create Client Instance

This client instance includes a set of functions for interacting with the Better Auth server instance. For more information, see here.

import { createAuthClient } from "better-auth/react"

export const authClient = createAuthClient()

Update the Route Handler

Rename the /app/api/auth/[...nextauth] folder to /app/api/auth/[...all] to avoid confusion. Then, update the route.ts file as follows:

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

export const { GET, POST } = handlers

import { auth } from "@/lib/auth";
import { toNextJsHandler } from "better-auth/next-js";

export const { POST, GET } = toNextJsHandler(auth)

Session Management

In this section, we'll look at how to manage sessions in Better Auth compared to Auth.js. For more information, see here.

Client-side

Sign In

Here are the differences between Auth.js and Better Auth for signing in users. For example, with the GitHub OAuth provider:

"use client"

import { signIn } from "next-auth/react"

signIn("github")

"use client"

import { authClient } from "@/lib/auth-client";

const { data, error } = await authClient.signIn.social({
  provider: "github",
})

Sign Out

Here are the differences between Auth.js and Better Auth when signing out users.

"use client"

import { signOut } from "next-auth/react"

signOut()

"use client"

import { authClient } from "@/lib/auth-client";

const { data, error } = await authClient.signOut()

Get Session

Here are the differences between Auth.js and Better Auth for getting the current active session.

"use client"

import { useSession } from "next-auth/react"

const { data, status, update } = useSession()

"use client"

import { authClient } from "@/lib/auth-client";

const { data, error, refetch, isPending, isRefetching } = authClient.useSession()

Server-side

Sign In

Here are the differences between Auth.js and Better Auth for signing in users. For example, with the GitHub OAuth provider:

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

await signIn("github")

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

const { redirect, url } = await auth.api.signInSocial({
  body: {
    provider: "github",
  },
})

Sign Out

Here are the differences between Auth.js and Better Auth when signing out users.

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

await signOut()

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

const { success } = await auth.api.signOut({
  headers: await headers(),
})

Get Session

Here are the differences between Auth.js and Better Auth for getting the current active session.

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

const session = await auth()

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

const session = await auth.api.getSession({
  headers: await headers(),
})

Protecting Resources

Proxy(Middleware) is not intended for slow data fetching. While Proxy can be helpful for optimistic checks such as permission-based redirects, it should not be used as a full session management or authorization solution. - Next.js docs

Auth.js offers approaches using Proxy (Middleware), but we recommend handling auth checks on each page or route rather than in a Proxy or Layout. Here is a basic example of protecting resources with Better Auth.

"use client";

import { authClient } from "@/lib/auth-client";
import { redirect } from "next/navigation";

const DashboardPage = () => {
  const { data, error, isPending } = authClient.useSession();

  if (isPending) {
    return <div>Pending</div>;
  }
  if (!data || error) {
    redirect("/sign-in");
  }

  return (
    <div>
      <h1>Welcome {data.user.name}</h1>
    </div>
  );
};

export default DashboardPage;

import { auth } from "@/lib/auth";
import { headers } from "next/headers";
import { redirect } from "next/navigation";

const DashboardPage = async () => {
  const session = await auth.api.getSession({
    headers: await headers(),
  });

  if (!session) {
    redirect("/sign-in");
  }

  return (
    <div>
      <h1>Welcome {session.user.name}</h1>
    </div>
  );
};

export default DashboardPage;

Database models

Both Auth.js and Better Auth provide stateless (JWT) and database session strategies. If you were using the database session strategy in Auth.js and plan to continue using it in Better Auth, you will also need to migrate your database.

Just like Auth.js has database models, Better Auth also has a core schema. In this section, we'll compare the two and explore the differences between them.

User -> User

Session -> Session

Account -> Account

VerificationToken -> Verification

Comparison

Table: User

• name, email, and emailVerified are required in Better Auth, while optional in Auth.js
• emailVerified uses a boolean in Better Auth, while Auth.js uses a timestamp
• Better Auth includes createdAt and updatedAt timestamps

Table: Session

• Better Auth uses token instead of sessionToken
• Better Auth uses expiresAt instead of expires
• Better Auth includes ipAddress and userAgent fields
• Better Auth includes createdAt and updatedAt timestamps

Table: Account

• Better Auth uses camelCase naming (e.g. refreshToken vs refresh_token)
• Better Auth includes accountId to distinguish between the account ID and internal ID
• Better Auth uses providerId instead of provider
• Better Auth includes accessTokenExpiresAt and refreshTokenExpiresAt for token management
• Better Auth includes password field to support built-in credential authentication
• Better Auth does not have a type field as it's determined by the providerId
• Better Auth removes token_type and session_state fields
• Better Auth includes createdAt and updatedAt timestamps

Table: VerificationToken -> Verification

• Better Auth uses Verification table instead of VerificationToken
• Better Auth uses a single id primary key instead of composite primary key
• Better Auth uses value instead of token to support various verification types
• Better Auth uses expiresAt instead of expires
• Better Auth includes createdAt and updatedAt timestamps

Customization

You may have extended the database models or implemented additional logic in Auth.js. Better Auth allows you to customize the core schema in a type-safe way. You can also define custom logic during the lifecycle of database operations. For more details, see Concepts - Database.