> ## 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 |
| - | - | - | - | - |
| `api_key` | *Optional\[str]* | :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` | *str* | :heavy\_check\_mark: | Partner's end-user identifier for attribution. | partner-user-123 |