Kling-4.0 Image to Video

curl --request POST \
  --url https://api.evolink.ai/v1/videos/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "kling-v4-image-to-video",
  "prompt": "The person in the image slowly turns their head and smiles",
  "image_start": "https://example.com/portrait.jpg",
  "duration": 5,
  "quality": "720p"
}
'

{
  "created": 1757169743,
  "id": "task-unified-1757169743-7cvnl5zw",
  "model": "kling-v4-image-to-video",
  "object": "video.generation.task",
  "progress": 0,
  "status": "pending",
  "task_info": {
    "can_cancel": true,
    "estimated_time": 300,
    "video_duration": 5
  },
  "type": "video",
  "usage": {
    "billing_rule": "per_second",
    "credits_reserved": 53.38,
    "user_group": "default"
  }
}

{
  "error": {
    "code": "invalid_request",
    "message": "Invalid request parameters",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired token",
    "type": "authentication_error"
  }
}

{
  "error": {
    "code": "insufficient_quota",
    "message": "Insufficient quota. Please top up your account.",
    "type": "insufficient_quota"
  }
}

{
  "error": {
    "code": "model_access_denied",
    "message": "Token does not have access to model: kling-v4-image-to-video",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests, please try again later",
    "type": "rate_limit_error"
  }
}

{
  "error": {
    "code": "internal_error",
    "message": "Internal server error",
    "type": "api_error"
  }
}

POST

videos

generations

curl --request POST \
  --url https://api.evolink.ai/v1/videos/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "kling-v4-image-to-video",
  "prompt": "The person in the image slowly turns their head and smiles",
  "image_start": "https://example.com/portrait.jpg",
  "duration": 5,
  "quality": "720p"
}
'

{
  "created": 1757169743,
  "id": "task-unified-1757169743-7cvnl5zw",
  "model": "kling-v4-image-to-video",
  "object": "video.generation.task",
  "progress": 0,
  "status": "pending",
  "task_info": {
    "can_cancel": true,
    "estimated_time": 300,
    "video_duration": 5
  },
  "type": "video",
  "usage": {
    "billing_rule": "per_second",
    "credits_reserved": 53.38,
    "user_group": "default"
  }
}

{
  "error": {
    "code": "invalid_request",
    "message": "Invalid request parameters",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired token",
    "type": "authentication_error"
  }
}

{
  "error": {
    "code": "insufficient_quota",
    "message": "Insufficient quota. Please top up your account.",
    "type": "insufficient_quota"
  }
}

{
  "error": {
    "code": "model_access_denied",
    "message": "Token does not have access to model: kling-v4-image-to-video",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests, please try again later",
    "type": "rate_limit_error"
  }
}

{
  "error": {
    "code": "internal_error",
    "message": "Internal server error",
    "type": "api_error"
  }
}

Authorizations

Authorization

string

header

required

All APIs require Bearer Token authentication

Get API Key:

Visit API Key Management Page to get your API Key

Add to request header:

Authorization: Bearer YOUR_API_KEY

Body

application/json

model

enum<string>

default:kling-v4-image-to-video

required

Video generation model name

Available options:

kling-v4-image-to-video

Example:

"kling-v4-image-to-video"

image_start

string<uri>

required

First frame image URL for image-to-video generation (required)

Note:

Image size: up to 10MB
Supported formats: .jpg, .jpeg, .png
Image dimensions: width and height >= 300px, aspect ratio between 1:2.5 and 2.5:1
Image URL must be directly accessible by the server or trigger a direct download when accessed

Example:

"https://example.com/portrait.jpg"

prompt

string

required

Text prompt describing the video to generate

Note:

Maximum 2500 characters

Maximum string length: 2500

Example:

"The person in the image slowly turns their head and smiles"

image_end

string<uri>

Last frame image URL

Note:

image_start (first frame) must be provided when using last frame
Supported formats: .jpg, .jpeg, .png
Image size: up to 10MB
Image URL must be directly accessible by the server or trigger a direct download when accessed

Example:

"https://example.com/night.jpg"

keyframes

object[]

Intermediate frame images, evenly spaced in order between the first and last frames

Note:

Count: 1 to 8 images
The first frame, intermediate frames, and last frame combined must not exceed 10 images or duration + 1 (for example, up to 4 images for 3 seconds or 6 images for 5 seconds)
The last frame is optional. If omitted, the model generates the ending frame
Image size: up to 10MB
Supported formats: .jpg, .jpeg, .png
Image dimensions: width and height >= 300px, aspect ratio between 1:2.5 and 2.5:1
Image URL must be directly accessible by the server or trigger a direct download when accessed

Maximum array length: 8

Show child attributes

Example:

[
  {
    "image_url": "https://example.com/half-open.jpg"
  },
  {
    "image_url": "https://example.com/open.jpg"
  }
]

duration

integer

default:5

Video duration in seconds. Defaults to 5 seconds

Range:

Integer from 3 to 30

Required range: 3 <= x <= 30

Example:

5

quality

enum<string>

default:720p

Resolution tier

Options:

720p: Standard 720P
1080p: High quality 1080P

Available options:

720p,

1080p

Example:

"720p"

callback_url

string<uri>

HTTPS callback URL for task completion

Callback Timing:

Triggered when task is completed, failed, or cancelled
Sent after billing confirmation

Security Restrictions:

HTTPS protocol only
Internal IP addresses are prohibited (127.0.0.1, 10.x.x.x, 172.16-31.x.x, 192.168.x.x, etc.)
URL length must not exceed 2048 characters

Callback Mechanism:

Timeout: 10 seconds
Maximum 3 retries after failure (at 1/2/4 seconds after failure)
Callback response format is consistent with task query API
2xx status code is considered successful, other codes trigger retry

Example:

"https://your-domain.com/webhooks/video-task-completed"

Response

Video generation task created successfully

created

integer

Task creation timestamp

Example:

1757169743

string

Task ID

Example:

"task-unified-1757169743-7cvnl5zw"

model

string

Actual model name used

Example:

"kling-v4-image-to-video"

object

enum<string>

Task type

Available options:

video.generation.task

progress

integer

Task progress percentage (0-100)

Required range: 0 <= x <= 100

Example:

0

status

enum<string>

Task status

Available options:

pending,

processing,

completed,

failed

Example:

"pending"

task_info

object

Video task details

Show child attributes

type

enum<string>

Task output type

Available options:

text,

image,

audio,

video

Example:

"video"

usage

object

Usage and billing information

Show child attributes

Image Series

Video Series

Audio Series

Text Series

Account Management

Task Management

File Management

Kling-4.0 Image to Video

Authorizations

All APIs require Bearer Token authentication

Body

Response