> ## Documentation Index
> Fetch the complete documentation index at: https://auth0.com/llms.txt
> Use this file to discover all available pages before exploring further.

> Configure Universal Login to enable passwordless authentication via a one-time code sent to a user's email address or phone number.

# Configure Email or SMS for Passwordless Authentication

Auth0 lets you configure <Tooltip tip="Universal Login: Your application redirects to Universal Login, hosted on Auth0's Authorization Server, to verify a user's identity." cta="View Glossary" href="/docs/glossary?term=Universal+Login">Universal Login</Tooltip> so users can authenticate with a magic link or one-time password (OTP) through email, or an OTP through SMS.

To enable <Tooltip tip="Passwordless: Form of authentication that does not rely on a password as the first factor." cta="View Glossary" href="/docs/glossary?term=Passwordless">Passwordless</Tooltip> authentication with SMS or email, you need to define a [Passwordless connection](/docs/authenticate/passwordless) for your application.

Once you've created the connection, you need to configure Universal Login to use it. You have three options:

## Universal Login

This method uses the Universal Login Experience, which natively supports Passwordless connections. To learn more, read [Passwordless with Universal Login](/docs/authenticate/passwordless/passwordless-with-universal-login).

## Universal Login + Lock (passwordless)

This method uses a custom login page with the **Lock (passwordless)** template, and authenticates user with the [Lock for Web SDK](/docs/libraries/lock):

1. Go to [Dashboard > Branding > Universal Login](https://manage.auth0.com/#/login_settings) and click the **Login** tab.
2. Enable the **Custom Login Page** toggle, and select the **Lock (passwordless)** template. The HTML template will update with code using the Lock widget with Passwordless customization options.
3. Customize the template, and click **Save Changes**.

You can use HTML and CSS to customize the login form, and preview the changes within the Dashboard. To learn more about how to customize the **Lock (passwordless)** template, read the Passwordless section in [Lock for Web SDK](/docs/libraries/lock).

## Universal Login + Custom UI + Auth0.js

This method uses a custom login page with the **Custom Login Form** template, and authenticates users with the [Auth0.js SDK](/docs/libraries/auth0js). To learn more, read [Passwordless Authentication with Universal Login](/docs/authenticate/passwordless/implement-login/universal-login).

## Learn more

* [Configure Universal Login with Passwordless](/docs/authenticate/login/auth0-universal-login/passwordless-login)
* [Configure WebAuthn with Device Biometrics for Passwordless Authentication](/docs/authenticate/login/auth0-universal-login/passwordless-login/webauthn-device-biometrics)