> ## 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.

# CreateEndUserRequest

## Fields

| Field | Type | Required | Description | Example |
| - | - | - | - | - |
| `User` | `string` | ✅ | Immutable case-sensitive tracking string supplied as user on inference requests or as external.user on API keys: 1 to 512 characters, well-formed Unicode, no NUL, no surrounding whitespace. URL-encode it in resource paths; an ID of `.` or `..` cannot be addressed by path, so look it up with the list filter. | employee\_123 |