Auth0.js v9 Reference

Auth0.js is a client-side library for Auth0. It is recommended for use in conjunction with Universal Login, which should be used whenever possible. Using auth0.js in your SPA makes it easier to do authentication and authorization with Auth0.

The full API documentation for the library is here.

Embedded login for web uses Cross Origin Authentication. In some browsers this can be unreliable if you do not set up a Custom Domain and host your app on the same domain. Using Custom Domains with Auth0 is a paid feature. If you cannot use Custom Domains, consider migrating to Universal Login.

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. In order to run it, follow these quick steps:

  1. If you don't have node installed, do that now

  2. Download dependencies by running npm install from the root of this project

  3. 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.

Set up and initialization

Now, let's get started integrating auth0.js into your project. We'll cover methods of installation, how to initialize auth0.js, signup, login, logout, and more!

Configure your Auth0 application for embedded login

When implementing embedded login, the library will use 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 will be hosting 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

Include via our CDN:

<script src=""></script>

If you are using a bundler, you will want to install with:

npm i auth0-js --production --save


Initialize a new instance of the Auth0 application as follows:

<script type="text/javascript">
  var webAuth = new auth0.WebAuth({
    domain:       'YOUR_DOMAIN',
    clientID:     'YOUR_CLIENT_ID'

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.
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 scope(s) 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.


The default scope value in auth0.js v9 is openid profile email.

Running Auth0.js locally

If you don't specify at least the above scope when initializing auth0.js, and you are running your website from http://localhost or, 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 email

That 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 auth you need in your application.


The authorize() method can be used for logging in users via Universal Login, or via social connections, as exhibited in the examples below. This method invokes the /authorize endpoint of the Authentication API, and can take a variety of parameters via 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 Refresh Token.
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 apps so the current state is not lost by doing a full page redirection.

Default authorization with popup (users see Auth0's Universal Login):

  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:

  redirectUri: 'https://YOUR_APP/popup_response_handler.html',
  connection: 'twitter'
}, function(err, authResult) {
  //do something

Handling popup authentication results

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:

to configure this snippet with your account

<!-- popup_response_handler.html -->
    <script src=""></script>
    <script type="text/javascript">
      var webAuth = new auth0.WebAuth({
        domain:       'YOUR_AUTH0_DOMAIN',
        clientID:     'YOUR_CLIENT_ID'
An ideal handler would contain just this minimal functionality (i.e. 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.


Embedded login for web uses Cross Origin Authentication. In some browsers this can be unreliable if you do not set up a Custom Domain and host your app on the same domain. Using Custom Domains with Auth0 is a paid feature. If you cannot use Custom Domains, consider migrating to Universal Login.

The login method allows for 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. See realm documentation for more information

  realm: 'tests',
  username: 'testuser',
  password: 'testpass',


The crossOriginVerification() method can be used to help provide cross-origin authentication to customers who have third-party cookies disabled in their browsers. Further details about its usage can be read in the cross-origin authentication document.


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.

to configure this snippet with your account

// Calculate URL to redirect to
var url = webAuth.client.buildAuthorizeUrl({
  clientID: 'YOUR_CLIENT_ID', // string
  responseType: 'token id_token', // code
  redirectUri: 'https://YOUR_APP/callback',
  state: 'YOUR_STATE',
  nonce: 'YOUR_NONCE'

// Redirect to url
// ...

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

Apps with embedded login must meet two criteria in order to have Single Sign-on (SSO).

  1. Both of the applications attempting SSO must be first-party applications. SSO with third-party applications will not work.

  2. They need to make use of custom domains and have both the applications which intend to have SSO as well as the Auth0 tenant on the same domain. Traditionally, Auth0 domains are in the format, but custom domains allow you to use the same domain for each of the applications in question as well as your Auth0 tenant, preventing the risk of CSRF attacks.

Our recommendation is to use Universal Login instead of setting up SSO in embedded login scenarios. Universal Login is the most reliable and stable way to perform SSO, and is the only way to do so if you must use multiple domains for your applications, or use third-party applications.

Passwordless login

Passwordless authentication allows users to log in by receiving a one-time password via 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 via 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).

In order to use Passwordless, you will want to initialize auth0.js with a redirectUri and to set the responseType: 'token'.

to configure this snippet with your account

var webAuth = new auth0.WebAuth({
  clientID: 'YOUR_CLIENT_ID',
  domain: 'YOUR_DOMAIN',
  redirectUri: '',
  responseType: 'token id_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.

    connection: 'email',
    send: 'code',
    email: ''
  }, 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.

In order to use passwordlessLogin, the options redirectUri and responseType must be specified when first initializing WebAuth.

    connection: 'email',
    email: '',
    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.
nonce 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 Access Token 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": "",
    "picture": "",
    "updated_at": "2018-05-07T14:16:52.013Z",
    "email": "",
    "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 Management API, 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({nonce: '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:

  nonce: '1234',
}, function (err, authResult) {

The webAuth.checkSession method will automatically verify that the returned ID Token'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 an email 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 is not allowed.


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.

  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) {
            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!')

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 audience 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:

    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 () {
      connection: 'db-conn',
      email:   ''
    }, function (err, resp) {
The user will then receive an email which will contain a link that they can follow to reset their password.

User management

The Management API provides functionality that allows you to link and unlink separate user accounts from different providers, tying them to a single profile (See User Account Linking for details.) It also allows you to update user metadata.

To get started, you first need to obtain a an Access Token that can be used to call the Management API. You can do it by specifying the https://YOUR_DOMAIN/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.

var webAuth = new auth0.WebAuth({
  clientID: 'YOUR_CLIENT_ID',
  domain: 'YOUR_DOMAIN',
  redirectUri: '',
  audience: `https://YOUR_DOMAIN/api/v2/`,
  scope: 'read:current_user',
  responseType: 'token id_token'

You can also do so by using checkSession():

    audience: `https://YOUR_DOMAIN/api/v2/`,
    scope: 'read:current_user'
  }, function(err, result) {
     // use result.accessToken

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.

var auth0Manage = new auth0.Management({
  domain: 'YOUR_DOMAIN',
  token: 'ACCESS_TOKEN'

Getting the user profile

In order 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);

Updating 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. See the Metadata documentation for more details on user metadata. auth0Manage.patchUserMetadata(userId, userMetadata, cb);

Linking 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, e.g., 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.