# User Attributes

User attributes are the profile fields you let your members keep on their own record. You define the list of attributes once for your organization — each with a name, a type, and a stable key — and then every member can have a value for each one.

Unlike raw member metadata, user attributes are **controlled**: only the attributes you have defined can be read or written through the Allegro APIs. This is the foundation for a member preference center, where a signed-in member can manage settings like newsletter opt-ins, content preferences, or a favorite topic.

## How they work[​](#how-they-work "Direct link to How they work")

* You define attributes in **Organization Settings → User Attributes**.
* Each attribute has a **slug** that maps to a single key on the member's profile. This is where the value is stored.
* Each attribute has a **type** (text, number, boolean, or a fixed set of choices) that Allegro uses to validate and cast values.
* Members set their own values through the Browser SDK, or your backend sets them through the REST API. See [Setting values](#setting-values).
* A member's current values are included in their signed session token (JWT) so your site can read them without an extra request.

## Defining an attribute[​](#defining-an-attribute "Direct link to Defining an attribute")

Open **Organization Settings → User Attributes** and click **New attribute**. You provide:

| Field              | Required | Description                                                                            |
| ------------------ | -------- | -------------------------------------------------------------------------------------- |
| **Attribute Name** | Yes      | The human-readable label, e.g. *Wants Newsletter*.                                     |
| **Slug**           | Yes      | The key the value is stored under, e.g. `wants-newsletter`. Auto-filled from the name. |
| **Description**    | No       | An optional note describing what the attribute is for.                                 |
| **Type**           | Yes      | How the value is validated and cast. See [Attribute types](#attribute-types).          |
| **Options**        | Enum     | One choice per line. Shown and required only when the type is **Select (enum)**.       |

The slug auto-fills as you type the name, but you can override it before saving.

The slug is permanent

The slug is the member profile key the value is stored under, so it **cannot be changed after the attribute is created**. On the edit form the slug field is locked. Pick it carefully — to rename the key you must delete the attribute and create a new one, which leaves the old values behind under the old slug.

## Attribute types[​](#attribute-types "Direct link to Attribute types")

| Type              | Stored value     | Notes                                                        |
| ----------------- | ---------------- | ------------------------------------------------------------ |
| **Text**          | A string         | Any free-form text.                                          |
| **Number**        | A number         | Whole numbers or decimals.                                   |
| **Boolean**       | `true` / `false` | A simple on/off flag.                                        |
| **Select (enum)** | One of a list    | Must match one of the **Options** you defined, one per line. |

Allegro validates every incoming value against the attribute's type. A value that doesn't match — a non-number for a Number attribute, or a choice outside the list for a Select attribute — is rejected.

## Editing an attribute[​](#editing-an-attribute "Direct link to Editing an attribute")

From the User Attributes list, click an attribute's name to edit its **name**, **description**, **type**, or **options**. The slug stays locked.

Changing the type of an attribute with existing values

Changing an attribute's type does not rewrite values members have already saved. Existing values are reinterpreted under the new type the next time they're read, which can produce unexpected results (for example, text that isn't a number becomes `0`). Change the type of a live attribute with care.

## Deleting an attribute[​](#deleting-an-attribute "Direct link to Deleting an attribute")

Deleting an attribute removes it from the list so it can no longer be read or written through the APIs or included in new tokens.

Member values are kept

Deleting an attribute definition **does not** erase the values members have already stored. The values remain on each member's profile under the slug. If you later re-create an attribute with the same slug, those existing values become visible again.

## Setting values[​](#setting-values "Direct link to Setting values")

You don't set member values from the admin UI — they're set programmatically:

* **Members set their own values** through the Allegro Browser SDK (`allegro.member.setUserAttribute(...)`). This is how a preference center on your site lets a signed-in member update their profile. See the [User Attributes SDK guide](/developer/guides/user-attributes.md).
* **Your backend sets values for any member** through the REST API, under `/v1/audience-members/{id}/user-attributes`. Reading requires the `audience-members:read` scope; writing requires `audience-members:write`. See the [REST API reference](/rest-api).

Writing to a slug that isn't a defined attribute is rejected — this is the control boundary that keeps arbitrary metadata out of the attribute APIs.

## Values in the session token[​](#values-in-the-session-token "Direct link to Values in the session token")

Each member's current attribute values are included in the signed session token (JWT) as a `user_attributes` claim, so your site can read a member's preferences directly from their token. Only attributes the member has a value for appear; each value is cast to its declared type. See [JWT Verification](/developer/guides/jwt.md) for the full token structure.

## Related[​](#related "Direct link to Related")

* [User Attributes SDK guide](/developer/guides/user-attributes.md) — Read and write a member's attributes from the browser.
* [JWT Verification](/developer/guides/jwt.md) — Read attribute values from the session token.
* [Members](/product/audience.md) — Browse and manage your audience.