# Custom Data Objects in UserDB

> ❗️  
> The max size of a custom data object in a UserDB record is 8 KB.

> ❗️  
> We recommend using either `camelCase` or `snake_case` custom property keys as these work well with Zerkel. However `kebab-case` should be avoided. Also, symbol prefixes (like `$`, `%`, `:`, etc.) should not be used.

> 👍  
> Note that the user key supplied in the `user` object will override a user key set via the `azk` cookie.

## Network ID

**Type:** int32  
**Required**  
Your account (network) ID

## Property

**Type:** string  
Appends one or more key/value pairs to be shipped to UserDB logs. In the format `?property:Key1=Value&property:Key2=Value` etc.

## Group

**Type:** 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 entire request.

## Key/Value Object

**Type:** string  
**Required**  
This is a JSON object that can be anything since it's custom data. For instance, `{"favoriteColor": "blue"}`.

# Example Request

```
curl -b "azk=ue1-e397eb5990" -X POST https://e-23.adzerk.net/udb/23/custom -d '{"favoriteColor":"blue"}'
```

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