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

# Kling V2.1 Master Text-to-Video

Kling V2.1 Text-to-Video is the latest generation text-to-video model developed by the Kuaishou AI team, capable of generating high-quality, cinematic short videos from text input. Compared to Kling 2.0, version 2.1 achieves significant breakthroughs in motion smoothness, visual consistency, and prompt comprehension.

<Tip>
  This is an **async** API that only returns the task\_id of the async task. Use the task\_id to call the [Get Async Task Result API](/docs/models/reference-get-async-task-result) to retrieve the generated result.
</Tip>

## Request Headers

<ParamField header="Content-Type" type="string" required={true}>
  Enum: `application/json`
</ParamField>

<ParamField header="Authorization" type="string" required={true}>
  Bearer authentication format: Bearer \{\{API Key}}.
</ParamField>

## Request Body

<ParamField body="prompt" type="string" required={true}>
  Positive text prompt to guide generation. Must not exceed 2500 characters.
</ParamField>

<ParamField body="duration" type="string" default="5">
  Duration of the generated video (in seconds).

  Possible values: `5`, `10`
</ParamField>

<ParamField body="aspect_ratio" type="string" default="16:9">
  Aspect ratio of the output video.

  Possible values: `16:9`, `9:16`, `1:1`
</ParamField>

<ParamField body="guidance_scale" type="number" default={0.5}>
  Guidance scale parameter that controls how closely the generated content adheres to the prompt.

  Range: 0 to 1<br />
  Step: 0.1
</ParamField>

<ParamField body="negative_prompt" type="string">
  Negative prompt to specify content to avoid in the generation. Must not exceed 2500 characters.
</ParamField>

## Response

<ResponseField name="task_id" type="string" required={true}>
  The task\_id of the async task. Use the task\_id to call the [Get Async Task Result API](/docs/models/reference-get-async-task-result) to retrieve the generated result.
</ResponseField>