- [JSON representation](https://developers.google.com/workspace/chat/api/reference/rest/v1/CardWithId#SCHEMA_REPRESENTATION)

A [card](https://developers.google.com/workspace/chat/api/reference/rest/v1/cards) in a Google Chat message.

Chat apps can create cards with [app authentication](https://developers.google.com/workspace/chat/authenticate-authorize-chat-app). As part of the [Developer Preview Program](https://developers.google.com/workspace/preview), if your Chat app [authenticates as a user](https://developers.google.com/workspace/chat/authenticate-authorize-chat-user), it can create card messages. If your Chat app is not part of Developer Preview Program, it can't create cards with user authentication.

To learn how to create a message that contains cards, see [Send a message](https://developers.google.com/workspace/chat/create-messages).

<br />

Design and preview cards with the Card Builder.
[Open the Card Builder](https://addons.gsuite.google.com/uikit/builder)

<br />

| JSON representation |
|---|
| ``` { "cardId": string, "card": { object (`https://developers.google.com/workspace/chat/api/reference/rest/v1/Card`) }, "ownerUser": { object (`https://developers.google.com/workspace/chat/api/reference/rest/v1/User`) } } ``` |

| Fields ||
|---|---|
| `cardId` | `string` Required if the message contains multiple cards. A unique identifier for a card in a message. |
| `card` | ``object (`https://developers.google.com/workspace/chat/api/reference/rest/v1/Card`)`` A card. Maximum size is 32 KB. |
| `ownerUser` | ``object (`https://developers.google.com/workspace/chat/api/reference/rest/v1/User`)`` Output only. The app that owns the card. |