Auth0.js - Auth0 Docs

The Auth0.js library is a client-side JavaScript library for Auth0. It supports both hosted login and embedded login use cases. This article covers v10, the current version. Review the full API documentation for the library.

Migrate from v9 to v10

Auth0.js v10 contains a security fix for CVE-2026-42280 and one breaking change:

Affected	Details
Apps using RS256	No breaking change
Apps using HS256	`parseHash()` now returns an `invalid_token` error instead of silently succeeding. Switch to RS256 in the Auth0 Dashboard: Applications > your app > Settings > Advanced Settings > OAuth > JsonWebToken Signature Algorithm > `RS256`

If you need the v9 API reference, see the auth0-js package on npm and select your v9 version, or browse the v9 source and changelog on GitHub.

Embedded login for web applications uses cross-origin authentication unless you configure a custom domain for your tenant. Cross-origin authentication uses third-party cookies to allow for secure authentication transactions across different origins.

Ready-to-go example

The example directory of the Auth0.js library is a ready-to-go app that can help you to quickly and easily try out Auth0.js. To run it:

If you don’t have node installed, do that now
Download dependencies by running npm install from the root of this project
Finally, execute npm start from the root of this project, and then browse to your app running on the node server, presumably at http://localhost:3000/example.

Setup and initialization

The following sections cover methods of installation, how to initialize Auth0.js, signup, login, logout, and more. When implementing embedded login, the library uses cross-origin calls inside hidden iframes to perform authentication. To make sure this can be done securely, Auth0 needs to know the domains where you host your applications. Add the domain to the Allowed Web Origins field. You can find this field in the Application Settings area of your Dashboard.

Installation options

You have a few options for using Auth0.js in your project. Pick one of the below depending on your needs: Install via npm or yarn:

npm install auth0-js

yarn add auth0-js

After installing the auth0-js module, bundle it up along with all of its dependencies, or import it using:

import auth0 from 'auth0-js';

Alternatively, include the script through the CDN:

<script src="https://cdn.auth0.com/js/auth0/10.0.0/auth0.min.js"></script>

Initialization

Initialize a new instance of the Auth0 application as follows:

Available parameters

There are two required parameters that must be passed in the options object when instantiating webAuth and more that are optional.

Parameter	Required	Description
`domain`	required	(String) Your Auth0 account domain (ex. myaccount.auth0.com)
`clientID`	required	(String) Your Auth0 client ID
`redirectUri`	optional*	(String) The default `redirectUri` used. Defaults to an empty string (none). *If you do not provide a global `redirectUri` value here, you will need to provide a redirectUri value for each* method you use.**
`scope`	optional	(String) The default used by the application. Using scopes can allow you to return specific claims for specific fields in your request. You should read our documentation on scopes for further details.
`audience`	optional	(String) The default audience to be used for requesting API access.
`responseType`	optional*	(String) The default `responseType` used. It can be any space separated list of the values `code`, `token`, `id_token`. It defaults to `'token'`, unless a `redirectUri` is provided, then it defaults to `'code'`. *If you do not provide a global `responseType` value, you will need to provide a `responseType` value for each* method you use.**
`responseMode`	optional	(String) This option is omitted by default. Can be set to `'form_post'` in order to send the token or code to the `'redirectUri'` via POST. Supported values are `query`, `fragment` and `form_post`.
`leeway`	optional	(Integer) A value in seconds; leeway to allow for clock skew with regard to ID Token expiration times.
`_disableDeprecationWarnings`	optional	(Boolean) Disables the deprecation warnings, defaults to `false`.

Because of clock skew issues, you may occasionally encounter the error The token was issued in the future. The leeway parameter can be used to allow a few seconds of leeway to ID Token expiration times, to prevent that from occurring.

Scope

The default scope value in Auth0.js v10 is openid profile email.

Running Auth0.js locallyIf you don’t specify at least the above scope when initializing Auth0.js, and you are running your website from http://localhost or http://127.0.0.1, calling the getSSOData() method will result in the following error in the browser console:Consent required. When using getSSOData, the user has to be authenticated with the following scope: openid profile emailThat will not happen when you run your application in production or if you specify the openid profile email scope. You can read more about this in the User consent and third-party applications document.

You can choose a method for login based on the type of authentication you need in your application.

webAuth.authorize()

The authorize() method can be used for logging in users through or social connections as shown in the examples below. This method invokes the /authorize endpoint of the Authentication API, and can take a variety of parameters through the options object.

Parameter	Required	Description
`audience`	optional	(String) The default audience to be used for requesting API access.
`connection`	optional	(String) Specifies the connection to use rather than presenting all connections available to the application.
`scope`	optional	(String) The scopes which you want to request authorization for. These must be separated by a space. You can request any of the standard OIDC scopes about users, such as `profile` and `email`, custom claims that must conform to a namespaced format, or any scopes supported by the target API (for example, `read:contacts`). Include `offline_access` to get a .
`responseType`	optional	(String) It can be any space separated list of the values `code`, `token`, `id_token`. It defaults to `'token'`, unless a `redirectUri` is provided, then it defaults to `'code'`.
`clientID`	optional	(String) Your Auth0 client ID.
`redirectUri`	optional	(String) The URL to which Auth0 will redirect the browser after authorization has been granted for the user.
`state`	optional	(String) An arbitrary value that should be maintained across redirects. It is useful to mitigate CSRF attacks and for any contextual information (for example, a return URL) that you might need after the authentication process is finished. For more information, see State Parameter. Auth0.js, when used in single-page applications, handles the state generation and validation automatically if not specified.
`prompt`	optional	(String) A value of `login` will force the login page to show regardless of current session. A value of `none` will attempt to bypass the login prompts if a session already exists (see the silent authentication documentation for more details).

For hosted login, one must call the /authorize() method. webAuth.authorize({//Any additional options can go here}); For social logins, the connection parameter will need to be specified: webAuth.authorize({connection: 'twitter'}); For popup authentication the popup.authorize method can be used. Popup authentication cannot be used within hosted login pages. Typically, popup authentication is used by single-page applications so the current state is not lost by doing a full page redirection. Default authorization with popup (Universal Login):

webAuth.popup.authorize({
  responseType: 'token'
  redirectUri: 'https://YOUR_APP/popup_response_handler.html'
  //Any additional options can go here
}, function(err, authResult) {
  //do something
});

And for social login with popup using authorize:

webAuth.popup.authorize({
  responseType: 'token'
  redirectUri: 'https://{yourApp}/popup_response_handler.html',
  connection: 'twitter'
}, function(err, authResult) {
  //do something
});

When using popup authentication, you’ll have to provide a redirectUri where the destination page communicates the authorization results back to the callback by using the webAuth.popup.callback method. A simple implementation would be something like this:

<!-- popup_response_handler.html -->
<html>
  <body>
    <script src="https://cdn.auth0.com/js/auth0/10.0.0/auth0.min.js"></script>
    <script type="text/javascript">
      var webAuth = new auth0.WebAuth({
        domain:       'YOUR_DOMAIN',
        clientID:     'YOUR_CLIENT_ID'
      });
      webAuth.popup.callback();
    </script>
  </body>
</html>

An ideal handler would contain only this minimal functionality (that is, avoid reloading the whole application just to handle the response). You will need to add the redirectUri to the application’s Allowed Callback URLs list in the application configuration page on the Dashboard.

The login method can be used for embedded login through cross-origin authentication for database connections, using /co/authenticate.

Parameter	Required	Description
`username`	optional	(String) The username to present for authentication. Either `username` or `email` must be present.
`email`	optional	(String) The email to present for authentication. Either `username` or `email` must be present.
`password`	required	(String) The password to present for authentication.
`realm`	required	(String) The name of the database connection against which to authenticate.

webAuth.login({
  realm: 'tests',
  username: 'testuser',
  password: 'testpass',
});

webAuth.crossOriginVerification()

The crossOriginVerification() method can be used to help provide cross-origin authentication to customers who have third-party cookies disabled in their browsers. To learn more about its usage, read Cross-Origin Authentication.

buildAuthorizeUrl(options)

The buildAuthorizeUrl method can be used to build the /authorize URL, in order to initialize a new transaction. Use this method if you want to implement browser based (passive) authentication. The state parameter is an opaque value that Auth0 will send back to you. This method helps prevent CSRF attacks, and it needs to be specified if you redirect to the URL yourself instead of calling webAuth.authorize(). For more information, see State Parameter.

Single Sign-On with embedded authentication

Embedded login supports (SSO) when your applications share the following architecture:

The applications attempting SSO are first-party applications. Sharing embedded sessions with third-party applications is not supported.
The applications and your Auth0 tenant share a top-level domain via a custom domain. Traditional Auth0 domains use the foo.auth0.com format; custom domains let your applications and Auth0 tenant share the same top-level domain, which also helps prevent CSRF attacks.

When your architecture meets these criteria, embedded SSO with Auth0.js is a good fit. Universal Login handles SSO across multiple domains or with third-party applications automatically through its session layer, and the two can coexist in the same app—for example, Universal Login for primary sign-in and Auth0.js for embedded factor enrollment or step-up flows. To compare the trade-offs, read Hosted Login vs. Embedded Login. authentication allows users to log in by receiving a one-time password through email or text message. The process will require you to start the passwordless process, generating and dispatching a code to the user (or a code within a link), followed by accepting their credentials through the verification method. That could happen in the form of a login screen which asks for their (email or phone number) and the code you just sent them. It could also be implemented in the form of a passwordless link instead of a code sent to the user. They would simply click the link in their email or text and it would hit your endpoint and verify this data automatically using the same verification method (just without manual entry of a code by the user). To use passwordless authentication, initialize Auth0.js with a redirectUri and set responseType: 'token'.

Start passwordless authentication

The first step in passwordless authentication with Auth0.js is the passwordlessStart method, which has several parameters which can be passed within its options object:

Parameter	Required	Description
`connection`	required	(String) Specifies how to send the code/link to the user. Value must be either `email` or `sms`.
`send`	required	(String) Value must be either `code` or `link`. If `null`, a link will be sent.
`phoneNumber`	optional	(String) The user’s phone number for delivery of a code or link via SMS.
`email`	optional	(String) The user’s email for delivery of a code or link via email.

Note that exactly one of the optional phoneNumber and email parameters must be sent in order to start the passwordless transaction.

webAuth.passwordlessStart({
    connection: 'email',
    send: 'code',
    email: 'foo@bar.com'
  }, function (err,res) {
    // handle errors or continue
  }
);

Complete passwordless authentication

If sending a code, you will then need to prompt the user to enter that code. You will process the code, and authenticate the user, with the passwordlessLogin method, which has several parameters which can be sent in its options object:

Parameter	Required	Description
`connection`	required	(String) Specifies how to send the code/link to the user. Value must be either `email` or `sms` and the same as the value passed to `passwordlessStart`.
`verificationCode`	required	(String) The code sent to the user, either as a code or embedded in a link.
`phoneNumber`	optional	(String) The user’s phone number to which the code or link was delivered via SMS.
`email`	optional	(String) The user’s email to which the code or link was delivered via email.

As with passwordlessStart, exactly one of the optional phoneNumber and email parameters must be sent in order to verify the passwordless transaction. To use passwordlessLogin, specify redirectUri and responseType when initializing WebAuth.

webAuth.passwordlessLogin({
    connection: 'email',
    email: 'foo@bar.com',
    verificationCode: '389945'
  }, function (err,res) {
    // handle errors or continue
  }
);

Extract the authResult and get user info

After authentication occurs, you can use the parseHash method to parse a URL hash fragment when the user is redirected back to your application in order to extract the result of an Auth0 authentication response. You may choose to handle this in a callback page that will then redirect to your main application, or in-page, as the situation dictates. The parseHash method takes an options object that contains the following parameters:

Parameter	Required	Description
`state`	optional	(String) An opaque value the application adds to the initial request that Auth0 includes when redirecting back to the application. This value is used by Auth0.js to prevent CSRF attacks.
	optional	(String) Used to verify the ID Token
`hash`	optional	(String) The URL hash (if not provided, `window.location.hash` will be used by default)

The contents of the authResult object returned by parseHash depend upon which authentication parameters were used. It can include:

Item	Description
`accessToken`	An for the API, specified by the `audience`
`expiresIn`	A string containing the expiration time (in seconds) of the `accessToken`
`idToken`	An ID Token JWT containing user profile information

webAuth.parseHash({ hash: window.location.hash }, function(err, authResult) {
  if (err) {
    return console.log(err);
  }

  webAuth.client.userInfo(authResult.accessToken, function(err, user) {
    // Now you have the user's information
  });
});

As shown above, the client.userInfo method can be called passing the returned accessToken. It will make a request to the /userinfo endpoint and return the user object, which contains the user’s information, formatted similarly to the below example.

{
    "sub": "auth0|123456789012345678901234",
    "nickname": "johnfoo",
    "name": "johnfoo@gmail.com",
    "picture": "https://gravatar.com/avatar/example.png",
    "updated_at": "2018-05-07T14:16:52.013Z",
    "email": "johnfoo@gmail.com",
    "email_verified": "false"
}

You can now do something else with this information as your application needs, such as acquire the user’s entire set of profile information with the , as described below.

Using nonces

By default (and if responseType contains id_token), Auth0.js will generate a random nonce when you call webAuth.authorize, store it in local storage, and pull it out in webAuth.parseHash. The default behavior should work in most cases, but some use cases may require a developer to control the nonce. If you want to use a developer generated nonce, then you must provide it as an option to both webAuth.authorize and webAuth.parseHash.

webAuth.authorize({<Tooltip tip="Nonce: Arbitrary number issued once in an authentication protocol to detect and prevent replay attacks." cta="View Glossary" href="/docs/glossary?term=nonce">nonce</Tooltip>: '1234', responseType: 'token id_token'}); webAuth.parseHash({nonce: '1234'}, callback);

If you’re calling webAuth.checkSession instead of webAuth.authorize, then you only have to specify your custom nonce as an option to checkSession:

webAuth.checkSession({
  nonce: '1234',
}, function (err, authResult) {
    ...
});

The webAuth.checkSession method will automatically verify that the returned ’s nonce claim is the same as the option.

Error codes and descriptions

When Auth0.js is used for embedded login, it employs the /co/authenticate endpoint, which can produce the following errors:

Error descriptions are intended to be human readable. The description should not be parsed by any code and is subject to change at any time.

Status	Code	Description
400	invalid_request	Invalid request body. All and only of client_id, credential_type, username, otp, realm are required.
401	unauthorized_client	Cross origin login not allowed.
400	unsupported_credential_type	Unknown credential type parameter.
400	invalid_request	Unknown realm non-existent-connection.
403	access_denied	Wrong email or password.
403	access_denied	Authentication error
403	blocked_user	Blocked user
401	password_leaked	This login attempt has been blocked because the password you’re using was previously disclosed through a data breach (not in this application).
429	too_many_attempts	Your account has been blocked after multiple consecutive login attempts. We’ve sent you a notification via your preferred contact method with instructions on how to unblock it.
429	too_many_attempts	We have detected suspicious login behavior and further attempts will be blocked. Please contact the administrator.

In addition, you can also get a generic 403 error without an error or error_description property. The response body would just include something similar to the following: Origin https://test.app is not allowed.

Logout

To log out a user, use the logout() method. This method accepts an options object, which can include the following parameters. If the clientID parameter is included, the returnTo URL that is provided must be listed in the Application’s Allowed Logout URLs in the Auth0 dashboard. However, if the clientID parameter is not included, the returnTo URL must be listed in the Allowed Logout URLs at the account level in the Auth0 dashboard.

webAuth.logout({
  returnTo: 'some url here',
  clientID: 'some client ID here'
});

To sign up a user, use the signup method. This method accepts an options object, which can include the following parameters.

Parameter	Required	Description
`email`	required	(String) User’s email address
`password`	required	(String) User’s desired password
`username`	required*	(String) User’s desired username. Required if you use a database connection and you have enabled Requires Username*
`connection`	required	(String) The database connection name on your application upon which to attempt user account creation
`user_metadata`	optional	(JSON object) Additional attributes used for user information. Will be stored in user_metadata

Signups should be for database connections. Here is an example of the signup method and some sample code for a form.

<h2>Signup Database Connection</h2>
<input class="signup-email" />
<input type="password" class="signup-password" />
<input type="button" class="signup-db" value="Signup!" />
<script type="text/javascript">
    $('.signup-db').click(function (e) {
        e.preventDefault();
        webAuth.signup({
            connection: 'Username-Password-Authentication',
            email: $('.signup-email').val(),
            password: $('.signup-password').val(),
            user_metadata: { plan: 'silver', team_id: 'a111' }
        }, function (err) {
            if (err) return alert('Something went wrong: ' + err.message);
            return alert('success signup without login!')
        });
    });
</script>

Using checkSession to acquire new tokens

The checkSession method allows you to acquire a new token from Auth0 for a user who is already authenticated against Auth0 for your domain. The method accepts any valid OAuth2 parameters that would normally be sent to authorize. If you omit them, it will use the ones provided when initializing Auth0. The call to checkSession can be used to get a new token for the API that was specified as the when webAuth was initialized:

webAuth.checkSession({}, function (err, authResult) {
  // err if automatic parseHash fails
  ...
});

See Extract the AuthResult and Get User Info for the format of authResult. Or, the token can be acquired for a different API than the one used when initializing webAuth by specifying an audience and scope:

webAuth.checkSession(
  {
    audience: `https://mydomain/another-api/˜`,
    scope: 'read:messages'
  }, function (err, authResult) {
  // err if automatic parseHash fails
  ...
});

Note that checkSession() triggers any rules you may have set up, so you should check on your rules in the Dashboard prior to using it. The actual redirect to /authorize happens inside an iframe, so it will not reload your application or redirect away from it. However, the browser must have third-party cookies enabled. Otherwise, checkSession() is unable to access the current user’s session (making it impossible to obtain a new token without displaying anything to the user). The same will happen if users have Safari’s ITP enabled. Remember to add the URL where the authorization request originates from, to the Allowed Web Origins list of your Auth0 application in the Dashboard under your application’s Settings.

If the connection is a social connection and you are using Auth0 dev keys, the checkSession call will always return login_required.

Polling with checkSession()

In some multi-application scenarios, where Single Logout is desired (a user logging out of one application needs to be logged out of other applications), an application can be set up to periodically poll Auth0 using checkSession() to see if a session exists. If the session does not exist, you can then log the user out of the application. The same polling method can be used to implement silent authentication for a Single Sign-on (SSO) scenario. The poll interval between checks to checkSession() should be at least 15 minutes between calls to avoid any issues in the future with rate limiting of this call.

Password reset requests

If attempting to set up a password reset functionality, you’ll use the changePassword method and pass in an options object, with a connection parameter and an email parameter.

$('.change_password').click(function () {
    webAuth.changePassword({
      connection: 'db-conn',
      email:   'foo@bar.com'
    }, function (err, resp) {
      if(err){
        console.log(err.message);
      }else{
        console.log(resp);
      }
    });
  });

The user receives an email containing a link to reset their password.

User management

The Management API provides functionality that allows you to link and unlink separate user accounts from different providers and update user metadata. For more information, read User Account Linking. To get started, you first need to obtain a an that can be used to call the Management API. You can do it by specifying the https://{yourDomain}/api/v2/ audience when initializing Auth0.js, in which case you will get the access token as part of the authentication flow. If you use custom domains, you will need to instantiate a new copy of webAuth using your Auth0 domain rather than your custom one, for use with the Management API calls, as it only works with Auth0 domains. You can also do so by using checkSession(): You must specify the specific scopes you need. You can ask for the following scopes:

read:current_user
update:current_user_identities
create:current_user_metadata
update:current_user_metadata
delete:current_user_metadata
create:current_user_device_credentials
delete:current_user_device_credentials

Once you have the access token, you can create a new auth0.Management instance by passing it the account’s Auth0 domain, and the access token.

Get the user profile

To get the user profile data, use the getUser() method, with the userId and a callback as parameters. The method returns the user profile. Note that the userID required here will be the same one fetched from the client.userInfo method. auth0Manage.getUser(userId, cb);

Update the user profile

When updating user metadata, you will need to first create a userMetadata object, and then call the patchUserMetadata method, passing it the user id and the userMetadata object you created. The values in this object will overwrite existing values with the same key, or add new ones for those that don’t yet exist in the user metadata. For more information, read Metadata. auth0Manage.patchUserMetadata(userId, userMetadata, cb);

Link users

Linking user accounts will allow a user to authenticate from any of their accounts and no matter which one they use, still pull up the same profile upon login. Auth0 treats all of these accounts as separate profiles by default, so if you wish a user’s accounts to be linked, this is the way to go. The linkUser method accepts two parameters, the primary userId and the secondary user’s ID Token (the token obtained after login with this identity). The user ID in question is the unique identifier for the primary user account. The ID should be passed with the provider prefix, for example, auth0|1234567890 or facebook|1234567890, when using this method. See User Account Linking for details. auth0Manage.linkUser(userId, secondaryUserToken, cb); After linking the accounts, the second account will no longer exist as a separate entry in the user database, and will only be accessible as part of the primary one. When accounts are linked, the secondary account’s metadata is not merged with the primary account’s metadata, and if they are ever unlinked, the secondary account will likewise not retain the primary account’s metadata when it becomes separate again.

​Migrate from v9 to v10

​Ready-to-go example

​Setup and initialization

​Configure your Auth0 application for embedded login

​Installation options

​Initialization

​Available parameters

Scope

​Login

​webAuth.authorize()

​webAuth.popup.authorize()

​Handle popup authentication results

​webAuth.login()

​webAuth.crossOriginVerification()

​buildAuthorizeUrl(options)

​Single Sign-On with embedded authentication

​Passwordless login

​Start passwordless authentication

​Complete passwordless authentication

​Extract the authResult and get user info

​Using nonces

​Error codes and descriptions

​Logout

​Signup

​Using checkSession to acquire new tokens

​Polling with checkSession()

​Password reset requests

​User management

​Get the user profile

​Update the user profile

​Link users

Migrate from v9 to v10

Ready-to-go example

Setup and initialization

Configure your Auth0 application for embedded login

Installation options

Initialization

Available parameters

Login

webAuth.authorize()

webAuth.popup.authorize()

Handle popup authentication results

webAuth.login()

webAuth.crossOriginVerification()

buildAuthorizeUrl(options)

Single Sign-On with embedded authentication

Passwordless login

Start passwordless authentication

Complete passwordless authentication

Extract the authResult and get user info

Using nonces

Error codes and descriptions

Logout

Signup

Using checkSession to acquire new tokens

Polling with checkSession()

Password reset requests

User management

Get the user profile

Update the user profile

Link users