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

# Check Username Availability

> Check whether Polymarket will accept a username.

```text theme={null}
GET /v3/polymarket/profiles/username-available
```

Use this endpoint before creating a challenge. It calls Polymarket's username availability check and returns the upstream result.

## Query parameters

| Parameter  | Type   | Required | Description                                                                                            |
| ---------- | ------ | -------- | ------------------------------------------------------------------------------------------------------ |
| `username` | string | Yes      | Desired username. Local validation is `^[A-Za-z0-9_]{3,32}$`. Polymarket is still the final authority. |

## Example

```bash theme={null}
curl "https://api.polynode.dev/v3/polymarket/profiles/username-available?username=alice123" \
  -H "x-api-key: pn_live_..."
```

```json theme={null}
{
  "username": "alice123",
  "available": true,
  "source": "polymarket"
}
```

Unavailable usernames return `200` with `available: false`:

```json theme={null}
{
  "username": "alice_123",
  "available": false,
  "source": "polymarket"
}
```

## Errors

| Status | Code                   | Meaning                                  |
| ------ | ---------------------- | ---------------------------------------- |
| `400`  | `invalid_username`     | Missing username or invalid local format |
| `401`  | varies                 | Missing or invalid PolyNode API key      |
| `402`  | varies                 | Paid plan required                       |
| `429`  | `rate_limited`         | Profile-specific rate limit exceeded     |
| `502`  | `upstream_unavailable` | Polymarket availability check failed     |