Kling 2.1 API: Standard, Pro & Master Video Modes

Overview

Kling 2.1 is a tiered Kuaishou video model for image-to-video generation and master-quality text-to-video generation. Use this page when you are ready to call the API after trying the model in the APIXO playground.

Capability	Value
Model ID	`kling-2-1`
Modes	`standard-image-to-video`, `pro-image-to-video`, `master-text-to-video`, `master-image-to-video`
Prompt length	1-5000 characters
Duration	`5` or `10` seconds
Reference images	None for `master-text-to-video`; exactly 1 for `standard-image-to-video` and `master-image-to-video`; 1-2 for `pro-image-to-video`
Aspect ratios	`16:9`, `9:16`, `1:1` for `master-text-to-video` only
Output format	MP4 URLs in `resultJson.resultUrls`

Endpoint and authentication

Base URL:

https://api.apixo.ai/api/v1

Method	Endpoint	Purpose
`POST`	`/generateTask/kling-2-1`	Submit a generation task
`GET`	`/statusTask/kling-2-1?taskId={taskId}`	Poll task status and retrieve results

All requests require your APIXO API key:

Authorization: Bearer YOUR_API_KEY

Submit requests also require:

Content-Type: application/json

Copy-paste async quickstart

This minimal request submits a standard image-to-video task and returns a taskId.

curl -X POST "https://api.apixo.ai/api/v1/generateTask/kling-2-1" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "request_type": "async",
    "input": {
      "mode": "standard-image-to-video",
      "prompt": "animate this still life scene with subtle camera movement",
      "duration": 5,
      "image_urls": [
        "https://example.com/source.jpg"
      ]
    }
  }'

Successful response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678"
  }
}

Save the taskId; you need it to poll for the final result.

Poll for result

curl -X GET "https://api.apixo.ai/api/v1/statusTask/kling-2-1?taskId=task_12345678" \
  -H "Authorization: Bearer YOUR_API_KEY"

Processing response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "processing",
    "createTime": 1767965610929
  }
}

Success response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "success",
    "resultJson": "{\"resultUrls\":[\"https://file.apixo.ai/xxx.mp4\"]}",
    "createTime": 1767965610929,
    "completeTime": 1767965710132,
    "costTime": 99203
  }
}

Failed response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "failed",
    "failCode": "SensitiveContent",
    "failMsg": "Content was rejected by safety checks, please adjust the prompt",
    "createTime": 1767965610929,
    "completeTime": 1767965620132,
    "costTime": 9203
  }
}

Parse resultJson after state becomes success:

const payload = JSON.parse(data.resultJson);
const videoUrls = payload.resultUrls;

Request body

Standard image-to-video

{
  "request_type": "async",
  "input": {
    "mode": "standard-image-to-video",
    "prompt": "animate this still life scene with subtle camera movement",
    "duration": 5,
    "image_urls": [
      "https://example.com/source.jpg"
    ],
    "negative_prompt": "blur, low quality",
    "cfg_scale": 0.6
  }
}

Pro image-to-video

{
  "request_type": "async",
  "input": {
    "mode": "pro-image-to-video",
    "prompt": "city skyline timelapse from day to night",
    "duration": 10,
    "image_urls": [
      "https://example.com/start.jpg",
      "https://example.com/end.jpg"
    ],
    "cfg_scale": 0.4
  }
}

Master text-to-video

{
  "request_type": "async",
  "input": {
    "mode": "master-text-to-video",
    "prompt": "a futuristic drone flying through neon-lit streets at night",
    "duration": 5,
    "aspect_ratio": "9:16",
    "negative_prompt": "grainy, noisy, static",
    "cfg_scale": 0.3
  }
}

Master image-to-video

{
  "request_type": "async",
  "input": {
    "mode": "master-image-to-video",
    "prompt": "turn this product photo into a premium cinematic reveal",
    "duration": 5,
    "image_urls": [
      "https://example.com/product.jpg"
    ]
  }
}

Parameters

string

default:"async"

Result delivery mode. Use async for polling with statusTask, or callback for webhook delivery.

string

Required when request_type is callback. Must be a public HTTPS URL that can receive the final task payload. See Webhooks.

object

required

Kling 2.1 input parameters.

Show properties

string

required

Generation mode. Supported values: standard-image-to-video, pro-image-to-video, master-text-to-video, master-image-to-video.

string

required

Text prompt describing the video. Must be a non-empty string with 1-5000 characters.

integer

required

Video duration in seconds. Supported values: 5 or 10.

string[]

Reference image URLs. Do not send this field for master-text-to-video. Send exactly 1 URL for standard-image-to-video and master-image-to-video. Send 1-2 URLs for pro-image-to-video; the second URL is accepted as an end-frame reference on routes that support tail-frame continuity. Each image must be JPG, JPEG, or PNG, no larger than 10 MB, and at least 300 pixels on each side.

string

default:"16:9"

Output aspect ratio for master-text-to-video. Supported values: 16:9, 9:16, 1:1. If omitted in master-text-to-video, the backend sends 16:9. Image-to-video modes do not forward this field.

string

Negative prompt for unwanted visual elements. Maximum length is 500 characters. Blank values are not forwarded.

number

Prompt guidance scale. Supported range is 0 to 1 with step 0.1. Recommended range: 0.3-0.7.

Response format

Submit task response

POST /generateTask/kling-2-1 returns a task ID when the task is accepted:

integer

API status code. 200 means the task was accepted.

string

Human-readable status message.

string

Unique task identifier used with the status endpoint.

Status response fields

string

Unique task identifier.

string

Current task state: pending, processing, success, or failed.

string

JSON string containing the generated video URLs. Present when state is success.

string

Machine-readable failure code. Present when state is failed.

string

Human-readable failure message. Present when state is failed.

integer

Task creation timestamp in Unix milliseconds.

integer

Task completion timestamp in Unix milliseconds. Present after completion.

integer

Processing duration in milliseconds. Present after successful completion and often present after failure.

Webhook callback mode

Use callback mode when your backend should receive the final result automatically instead of polling.

curl -X POST "https://api.apixo.ai/api/v1/generateTask/kling-2-1" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "request_type": "callback",
    "callback_url": "https://your-server.com/webhooks/apixo",
    "input": {
      "mode": "master-text-to-video",
      "prompt": "a futuristic drone flying through neon-lit streets at night",
      "duration": 5,
      "aspect_ratio": "16:9"
    }
  }'

The callback payload uses the same unified response format as the status endpoint. See Webhooks for delivery requirements and retry behavior.

Billing

New non-LLM requests use 1 credit = $0.001. Calculate the full amount, including billable quantity and add-ons, apply the applicable account discount, then round the request total upward to the next whole credit. Agreed fixed unit prices retain their precision and replace the standard price and discount; final rounding still applies. See credit conversion and rounding. Kling 2.1 is billed per generated video. The selected mode determines the tier, and duration determines the unit price.

Mode	Tier	5 seconds	10 seconds
`standard-image-to-video`	Standard	`$0.20 / video`	`$0.40 / video`
`pro-image-to-video`	Pro	`$0.35 / video`	`$0.70 / video`
`master-text-to-video`	Master	`$1.00 / video`	`$2.00 / video`
`master-image-to-video`	Master	`$1.00 / video`	`$2.00 / video`

For current API rates in USD, see API pricing.

Latency and polling

Actual latency may vary by prompt complexity, selected tier, input image size, route, and current queue load.

Duration	Typical generation time	Recommended first poll	Poll interval
`5` seconds	60s-90s	60s after task creation	5s-10s
`10` seconds	90s-120s	60s after task creation	5s-10s

For production video workloads, use callback mode to avoid frequent polling. Result URLs are stored through APIXO and are generally available for 15 days, so download important outputs promptly.

Rate limits and concurrency can vary by account, API key, and route. If you receive 429, slow down requests and retry with backoff. For account-level details, see System APIs.

Errors and troubleshooting

HTTP errors

Code	Meaning	What to do
`400`	Invalid request body, missing required field, unsupported mode, or rejected input	Fix the request before retrying
`401`	Missing or invalid API key	Check the `Authorization` header
`402`	Insufficient balance or quota	Add balance or switch account/key
`403`	Key or route cannot access the model	Check permissions and routing settings
`429`	Rate limit or concurrency limit reached	Retry with exponential backoff
`500`	Server error	Retry with backoff
`502`	Service error	Retry with backoff
`504`	Service timeout	Retry or use callback mode for long-running jobs

Task failure codes

failCode identifies the task failure. Exact values can vary by failure.

Fail code	Meaning	What to do
`Missing required parameter`	A required field such as `input`, `mode`, `prompt`, `duration`, `image_urls`, or `callback_url` is missing	Add the missing field
`Invalid parameter type`	A field has the wrong JSON type	Check `prompt`, `duration`, `image_urls`, `aspect_ratio`, `negative_prompt`, and `cfg_scale`
`Invalid parameter value`	A field has an unsupported value	Check `mode`, `duration`, `aspect_ratio`, and `cfg_scale`
`Param length exceeded`	Prompt, negative prompt, or image count exceeds the backend limit	Shorten text or reduce image count
`ImageNotAccess`	An input image URL could not be fetched	Use a public, direct HTTP(S) image URL
`SensitiveContent`, `PromptInvalid`, `ProhibitedContentDetected`, `NSFW`	Prompt, input image, or output failed safety checks	Change the prompt or image
`RateLimited`	A rate limit was reached	Retry with backoff
`Timeout`	The task timed out	Retry, reduce input complexity, or use callback mode
`Unknown error`	An unknown task failure occurred	Retry with backoff or contact support with the `taskId`

Common request issues

Symptom	Likely cause	Fix
`mode` is rejected	The mode is missing or not one of the four supported values	Use `standard-image-to-video`, `pro-image-to-video`, `master-text-to-video`, or `master-image-to-video`
Text-to-video rejects `image_urls`	`master-text-to-video` does not allow reference images	Remove `image_urls`
Image-to-video rejects the request	Required image is missing or too many images were sent	Send exactly 1 image for standard/master image modes, or 1-2 images for pro mode
`aspect_ratio` appears ignored	The field only applies to `master-text-to-video`	Use `master-text-to-video` when aspect ratio control is required
Image URL fails before generation	The backend validates public URL reachability	Use a direct, reachable HTTP(S) URL and avoid private or localhost links

See Error Codes for the full error reference.

MCP integration

The complete model schema declares result decoding in mcp.result and supported file bindings in mcp.attachments. These are client integration metadata, not generation input parameters. Attachment paths: image_urls. Preserve the user’s file order. Model parameter validation remains on the API.

​Overview

​Endpoint and authentication

​Copy-paste async quickstart

​Poll for result

​Request body

​Standard image-to-video

​Pro image-to-video

​Master text-to-video

​Master image-to-video

​Parameters

​Response format

​Submit task response

​Status response fields

​Webhook callback mode

​Billing

​Latency and polling

​Errors and troubleshooting

​HTTP errors

​Task failure codes

​Common request issues

​MCP integration

​Related links

Overview

Endpoint and authentication

Copy-paste async quickstart

Poll for result

Request body

Standard image-to-video

Pro image-to-video

Master text-to-video

Master image-to-video

Parameters

Response format

Submit task response

Status response fields

Webhook callback mode

Billing

Latency and polling

Errors and troubleshooting

HTTP errors

Task failure codes

Common request issues

MCP integration

Related links