Auth0 distinguishes between three types of metadata used to store specific kinds of information.
Auth0 metadata is not a secure data store and should not be used to store sensitive information, such as high-risk secrets and Personally Identifiable Information (PII) like social security numbers or credit card numbers. Auth0 customers are strongly encouraged to evaluate the data stored in metadata and only store that which is necessary for identity and access management purposes.
Metadata TypeField NameDescription
User Informationuser_metadataStores user attributes such as preferences that do not impact a user’s core functionality. This data can be edited by logged in users if you build a form using the Management API and should not be used as a secure data store.
Access Informationapp_metadataStores information such as permissions, Auth0 plan, and external IDs that can impact user access to features. This data cannot be edited by users and there are restrictions for what can be stored in this field.
Application Informationclient_metadata in the Client object, context.clientMetadata in Rules, and event.client.metadata in post-login Actions.Stores information about an application (or client in OIDC OAuth2 terminology). For example, the URL for the application home page (any value that Auth0 doesn’t set in the application settings).

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Metadata field names

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Accepted characters

Field names must not contain the . (dot) or $ (dollar sign) characters. For example, this is not allowed: 
{
  "preference.color": "pink"
}
But you can expand it like this: 
{
    "preference": { 
        "color": "pink" 
    }
}

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Dynamic field names

Field names should be static. Dynamic field names reduce indexing efficiency and cause degradation in search queries. A static schema is easier to search, manipulate, and work with. Instead of doing this: 
{
    "participants": [
        "Alice": {
            "role": "sender"
         },
        "Bob": {
            "role": "receiver"
        }
    ]
}
Do this: 
{
    "participants": [
        {
            "name": "Alice",
            "role": "sender"
        },
        {
            "name" : "Bob",
            "role": "receiver"
        }
    ]
}

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Name collision

Avoid using the same name for app_metadata fields and root profile fields. The app_metadata field is merged onto the root profile in both Rules and Actions, which may override root profile fields. For example, if a user has a groups field present on their root profile (returned from a ) and a groups field within app_metadata, their profile might look like this: 
{
    "user_id": "samlp|example-samlp-connection|username@domain.com",
    "groups": [
        "external-group-1",
        "external-group-2"
    ],
    "app_metadata": {
        "groups": [
            "internal-group-1",
            "internal-group-2"
        ]
    }
}
When you read the groups field on the User object from a Rule, it will return: ["internal-group-1", "internal-group-2"].

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Metadata data types

Metadata fields support all JSON-compatible data types:
  • String
  • Number
  • Array
  • Object
Make sure to keep data types consistent between users. For example, if you store a value as a string for one user (user.user_metadata.age = "23") and as a number for another user (user.user_metadata.age = 23), you may encounter issues when retrieving the data.

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Limitations and restrictions

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Rate limits

When you update metadata during login with Rules or Actions, you are subject to your tenant’s rate limits. To learn more, read Management API Endpoint Rate Limits.
You should only store data related to user authentication in metadata. The storage and search capabilities of Auth0 are designed for use cases that do not require heavy search and/or update frequency.If you need to maintain detailed profile-related data for users, you should do so in an external system. You can store the user’s identifier from that system as a metadata field in Auth0.

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Size limits and storage

  • There is a 1 MB per-user limit on user data that can be indexed, queried, and returned by the user search endpoint. If a user profile is larger than 1 MB, any attribute values larger than 256 characters within app_metadata and user_metadata will not be searchable or returned in a search result. If the user profile is still over 1 MB after omitting these large values, then none of the app_metadata and user_metadata attributes will be searchable or returnable for that user. Auth0 captures and logs instances where a user profile is still over 1MB after omittances under the wum event code. The get user endpoint must be used to retrieve all metadata attributes for oversized user profiles.
  • When you set the user_metadata field using the Auth0 Authentication API Signup endpoint, you can include a maximum of 10 string fields whose values do not exceed 500 characters each. For an example of working with metadata during a custom signup process, read Custom Signup.
  • The client_metadata field can have a maximum of 10 keys. Its keys and values have a maximum length of 255 characters each and cannot contain UTF-8 special characters.

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Restrictions

The app_metadata field must not contain any of these properties:
  • __tenant
  • _id
  • blocked
  • clientID
  • created_at
  • email_verified
  • email
  • globalClientID
  • global_client_id
  • identities
  • lastIP
  • lastLogin
  • loginsCount
  • metadata
  • multifactor_last_modified
  • multifactor
  • updated_at
  • user_id

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