---
title: LINE
description: LINE provider setup and usage.
---

<Steps>
    <Step>
        ### Get your LINE credentials

        1. Create a channel in the LINE Developers Console.
        2. Note your Channel ID (client_id) and Channel secret (client_secret).
        3. In the channel settings, add your Redirect URI, e.g. `http://localhost:3000/api/auth/callback/line` for local development.
        4. Enable required scopes (at least `openid`; add `profile`, `email` if you need name, avatar, email).

        See LINE Login v2.1 reference for details: [`https://developers.line.biz/en/reference/line-login/#issue-access-token`]
    </Step>

    <Step>
        ### Configure the provider

        Add your LINE credentials to `socialProviders.line` in your auth configuration.

        ```ts title="auth.ts"
        import { betterAuth } from "better-auth";

        export const auth = betterAuth({
          socialProviders: {
            line: {
              clientId: process.env.LINE_CLIENT_ID as string,
              clientSecret: process.env.LINE_CLIENT_SECRET as string,
              // Optional: override redirect if needed
              // redirectURI: "https://your.app/api/auth/callback/line",
              // scopes are prefilled: ["openid","profile","email"]. Append if needed
            },
          },
        });
        ```
    </Step>
</Steps>

## Usage

### Sign In with LINE

Use the client `signIn.social` with `provider: "line"`.

```ts title="auth-client.ts"
import { createAuthClient } from "better-auth/client";
const authClient = createAuthClient();

async function signInWithLINE() {
  const res = await authClient.signIn.social({ provider: "line" });
}
```

### Sign In with LINE using ID Token (optional)

If you obtain the LINE ID token on the client, you can sign in directly without redirection.

```ts title="auth-client.ts"
await authClient.signIn.social({
  provider: "line",
  idToken: {
    token: "<LINE_ID_TOKEN>",
    accessToken: "<LINE_ACCESS_TOKEN>",
  },
});
```

### Notes

- Default scopes include `openid profile email`. Adjust as needed via provider options.
- Verify redirect URI exactly matches the value configured in LINE Developers Console.
- LINE ID token verification uses the official endpoint and checks audience and optional nonce per spec.

Designing a login button? Follow LINE's button [guidelines](https://developers.line.biz/en/docs/line-login/login-button/).

