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

# External

Optional partner-defined identity associated with the created API key.

## Fields

| Field    | Type      | Required             | Description                                                                                                                                   | Example          |
| -------- | --------- | -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- | ---------------- |
| `APIKey` | `*string` | :heavy\_minus\_sign: | Optional partner-supplied API key with a minimum length of 32 characters and sufficient entropy. Stored as a SHA-256 hash and never returned. |                  |
| `User`   | `string`  | :heavy\_check\_mark: | Partner's end-user identifier for attribution.                                                                                                | partner-user-123 |