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

# addFakeParticipant()

> Add a fake video participant to a call for testing layout and UI.

`addFakeParticipant(details?)`

<Badge color="green">{"✓"} Prebuilt</Badge> <Badge color="green">{"✓"} Custom</Badge>

Adds a fake participant with a synthetic video stream to the local call view. The fake participant exists only on the local client — they are not an actual participant in the call and are not visible to others. This is a convenience method for building and testing your UI without needing additional real devices or browser tabs.

## Parameters

<ParamField body="details.aspectRatio" type="number">
  Optional. The aspect ratio of the fake video stream. Supported values are `16/9`, `3/4`, and `4/3`. Defaults to `16/9`.
</ParamField>

## Return value

Returns `this` (the `DailyCall` instance), allowing method chaining.

## Example

```javascript theme={null}
// Add one fake participant with default 16:9 aspect ratio
call.addFakeParticipant();

// Add multiple fake participants to test grid layout
call.addFakeParticipant()
    .addFakeParticipant()
    .addFakeParticipant({ aspectRatio: 4/3 });
```

## See also

<CardGroup>
  <Card title="Methods" icon="code" iconType="solid">
    * [participants()](/reference/daily-js/instance-methods/participants)
  </Card>

  <Card title="Events" icon="bolt" iconType="solid">
    * [participant-joined](/reference/daily-js/events/participant-events#participant-joined)
  </Card>
</CardGroup>