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

# Identity

> Cross-platform user identity management

The **Identity** system lets you link a Qonversion User ID to your own authentication system's user ID. This enables cross-platform access — a user who logs in on both iOS and Android can share the same entitlements.

## How it works

1. A user installs your app → Qonversion SDK generates a `QON_` prefixed user ID
2. The user logs into your system → you call `identify()` with your user ID
3. Qonversion links the two IDs together
4. On another device, calling `identify()` with the same ID restores their entitlements

## Identity object

| Field     | Type   | Description                                |
| --------- | ------ | ------------------------------------------ |
| `id`      | string | Your custom user identity ID               |
| `user_id` | string | Qonversion User ID linked to this identity |

## Available endpoints

| Method | Endpoint                    | Description                                     |
| ------ | --------------------------- | ----------------------------------------------- |
| GET    | `/identities/{identity_id}` | Retrieve a Qonversion user by your identity ID  |
| POST   | `/identities/{identity_id}` | Create or link an identity to a Qonversion user |

## Authentication

All Identity endpoints require a **Project Key** in the `Authorization` header.