# API Request Parameters

## Parameters

| Parameter    | Type     | Description                                                                                                                                                                     |
|--------------|----------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| networkId    | int32    | Your account (network) ID                                                                                                                                                    |
| userKey      | string   | Required user authentication key.                                                                                                                                           |
| group        | integer  | Optional. Sets the user's incrementality group (1–100) as part of this request; use `group=null` to clear it, or omit to leave it unchanged. Invalid values reject the request. |
| RAW_BODY     | json     | A JSON object that can be anything since it's custom data. For instance, `{"favoriteColor": "blue"}`.                                                                    |
| accept       | string   | Defaults to application/json. Allowed: `application/json`, `text/plain`.                                                                                                   |

# HTTP Status Codes

- **200**: Request was successful.
- **400**: Bad request due to invalid parameters.

## Example CURL Request

```bash
curl -H "X-Adzerk-ApiKey: $ADZERK_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{"favoriteColor":"blue"}' \
     "https://e-23.adzerk.net/udb/23/customProperties?userKey=ue1-e397eb5990"
```

## Image Reference

Returns a 1x1 transparent GIF image.