Kling 4.0 · Image to Video

Guide Kling 4.0 video generation with a first frame, ordered middle frames and a last frame. Describe the motion between images, then query the asynchronous generation to retrieve the result.

Developer API pricing

Provider: SeeAPI

USD estimate: $0.0037 / credit · Estimated equivalent, not an additional charge.

720p: 38.1 credits/sec (≈ $0.14/sec)

1080p: 56.8 credits/sec (≈ $0.21/sec)

Request

POST/v1/generations

AuthorizationSend your API key in the Authorization header using the Bearer scheme.Authorization: Bearer ****************

Header Params

stringrequired

A unique key used to safely retry the same request.

Required; maximum 255 characters.
Reuse the same key only with the same request body.

max length: 255

Example:: order-20260818-001

Body Params

application/json

stringrequired

The model identifier.

Required. Use kling-4-0.

Allowed:kling-4-0

Default:: kling-4-0
Example:: kling-4-0

stringrequired

The generation capability to run.

Required. Use image-to-video.

Allowed:image-to-video

Default:: image-to-video
Example:: image-to-video

stringoptional

The public provider to use.

Optional. The default provider is seeapi.

Allowed:seeapi

Default:: seeapi
Example:: seeapi

objectrequired

The frame images, prompt and output settings for this generation.

Supply publicly reachable HTTPS image URLs. URLs must point to actual JPEG or PNG files.
The total number of first, middle and last frames must not exceed min(10, duration_seconds + 1). For a 5-second video, use at most 6 frames in total.

Provider parameters

SeeAPIseeapiDefault Provider

string <uri>optional

The image used as the first frame.

Optional. JPEG or PNG, at most 10 MB.
Use @first_frame in the prompt only when this image is supplied.

Example:: https://client.example.com/first.png

array <uri>optional

An ordered array of middle-frame image URLs guiding the progression between the first and last frames.

Optional; at most 8 middle frames. Each file must be JPEG or PNG and at most 10 MB.
All frames share the total limit min(10, duration_seconds + 1).
Reference supplied middle frames as @keyframe_1, @keyframe_2 and so on, in array order.

max items: 8

Example:: ["https://client.example.com/middle.png"]

string <uri>optional

The image used as the last frame.

Optional. JPEG or PNG, at most 10 MB.
Use @last_frame in the prompt only when this image is supplied.

Example:: https://client.example.com/last.png

stringrequired

Describe the actions, transitions and camera movement between the supplied frames.

Required; maximum 8000 characters.
Only mention frame references that are included in this request.

max length: 8000

Example:: Start from @first_frame, follow the subject walking toward the open doorway shown in @keyframe_1, and end with the composition of @last_frame. Smooth camera motion and consistent appearance.

numberoptional

The desired output video duration in seconds.

Optional. Use an integer from 3 to 30; default 5.
Increasing duration also changes the allowed total frame count, up to 10 frames.

min: 3max: 30

Default:: 5

stringoptional

The output video resolution.

Optional. Allowed values: 720p, 1080p. Default: 720p.

Allowed:720p1080p

Default:: 720p

stringoptional

The output frame aspect ratio.

Optional. Allowed values: auto, 16:9, 9:16, 1:1, 21:9. Default: auto.

Allowed:auto16:99:161:121:9

Default:: auto

string <uri>optional

An absolute HTTPS URL that receives the terminal generation webhook.

Optional; maximum 2048 characters.
Verify webhook signatures before processing callbacks.

max length: 2048

Example:: https://client.example.com/webhooks/seeapi

Responses

202The request was accepted for asynchronous processing.

Bodyapplication/json

Save generation.id and query the task until it reaches a terminal state.
This response does not contain the completed video.

objectrequired

The accepted generation and its current processing status.

stringrequired

The generation identifier. Save it to query status and retrieve the result.

Example:: task_xxx

stringrequired

The model used for this generation.

Example:: kling-4-0

stringrequired

The endpoint used for this generation.

Example:: image-to-video

stringrequired

The selected public provider.

Allowed:seeapi

seeapi: SeeAPI

Example:: seeapi

stringrequired

The current generation state. Processing does not mean the video is ready.

Allowed:processing

Example:: processing

numberrequired

The estimated charge in public credits for this request.

Example:: 190.5

numberrequired

Credits consumed by this generation so far.

Example:: 0

numberrequired

Credits refunded for this generation so far.

Example:: 0

string <date-time>required

The time the generation was created, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

string <date-time>required

The time the generation was last updated, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

booleanrequired

Whether this is a replay of an earlier request with the same idempotency key.

Example:: false

200An existing generation was returned for an idempotent replay.

Bodyapplication/json

The same idempotency key and request body return the original generation rather than creating another one.

objectrequired

The accepted generation and its current processing status.

stringrequired

The generation identifier. Save it to query status and retrieve the result.

Example:: task_xxx

stringrequired

The model used for this generation.

Example:: kling-4-0

stringrequired

The endpoint used for this generation.

Example:: image-to-video

stringrequired

The selected public provider.

Allowed:seeapi

seeapi: SeeAPI

Example:: seeapi

stringrequired

The current generation state. Processing does not mean the video is ready.

Allowed:processing

Example:: processing

numberrequired

The estimated charge in public credits for this request.

Example:: 190.5

numberrequired

Credits consumed by this generation so far.

Example:: 0

numberrequired

Credits refunded for this generation so far.

Example:: 0

string <date-time>required

The time the generation was created, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

string <date-time>required

The time the generation was last updated, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

booleanrequired

Whether this is a replay of an earlier request with the same idempotency key.

Example:: false

400

Invalid JSON, parameters, Schema, or API Policy

401

Invalid API Key or authentication failed

402

Insufficient credits

403

The current request is not allowed

404

Model, Endpoint, or task not found

409

Idempotency conflict or the same request is still being created

413

Request body is too large

429

Too many requests

503

Service temporarily unavailable

Related Resources

Market Overview

Explore all available models

Credits & Billing

View credit balance, plans, and billing activity

Usage

Review API usage and credit consumption

Query Task Status

After submitting a task, use the unified query endpoint to check progress and retrieve results:

Get Task DetailsLearn how to query task status and retrieve generation results

Submit requests from your server using a Bearer API key. Store generation.id and use Get Task Details to retrieve the result. Replace all example image URLs with publicly reachable HTTPS URLs for your actual images.

Callbacks

Manage the secret used to verify generation webhook signatures. Callback URLs are supplied when you create each generation.

Webhook flow

Callback URL per generation.

Webhook signing key

Code Examples

Request

const response = await fetch("https://api.seeapi.com/v1/generations", {
  method: "POST",
  headers: {
    "Authorization": "Bearer YOUR_API_KEY",
    "Idempotency-Key": "order-20260818-001",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
  "model": "kling-4-0",
  "endpoint": "image-to-video",
  "provider": "seeapi",
  "input": {
    "first_frame_image": "https://client.example.com/first.png",
    "keyframe_urls": [
      "https://client.example.com/middle.png"
    ],
    "last_frame_image": "https://client.example.com/last.png",
    "prompt": "Start from @first_frame, follow the subject walking toward the open doorway shown in @keyframe_1, and end with the composition of @last_frame. Smooth camera motion and consistent appearance.",
    "duration_seconds": 5,
    "resolution": "720p",
    "aspect_ratio": "auto"
  },
  "callback_url": "https://client.example.com/webhooks/seeapi"
})
});

const result = await response.json();

ResponseHTTP 202

{
  "generation": {
    "id": "task_xxx",
    "model": "kling-4-0",
    "endpoint": "image-to-video",
    "provider": "seeapi",
    "status": "processing",
    "estimated_credits": 190.5,
    "consumed_credits": 0,
    "refunded_credits": 0,
    "created_at": "2026-08-18T10:00:00Z",
    "updated_at": "2026-08-18T10:00:00Z"
  },
  "idempotent": false
}

const response = await fetch("https://api.seeapi.com/v1/generations", { method: "POST", headers: { "Authorization": "Bearer YOUR_API_KEY", "Idempotency-Key": "order-20260818-001", "Content-Type": "application/json" }, body: JSON.stringify({ "model": "kling-4-0", "endpoint": "image-to-video", "provider": "seeapi", "input": { "first_frame_image": "https://client.example.com/first.png", "keyframe_urls": [ "https://client.example.com/middle.png" ], "last_frame_image": "https://client.example.com/last.png", "prompt": "Start from @first_frame, follow the subject walking toward the open doorway shown in @keyframe_1, and end with the composition of @last_frame. Smooth camera motion and consistent appearance.", "duration_seconds": 5, "resolution": "720p", "aspect_ratio": "auto" }, "callback_url": "https://client.example.com/webhooks/seeapi" }) }); const result = await response.json();

{ "generation": { "id": "task_xxx", "model": "kling-4-0", "endpoint": "image-to-video", "provider": "seeapi", "status": "processing", "estimated_credits": 190.5, "consumed_credits": 0, "refunded_credits": 0, "created_at": "2026-08-18T10:00:00Z", "updated_at": "2026-08-18T10:00:00Z" }, "idempotent": false }

Responses

202The request was accepted for asynchronous processing.

Bodyapplication/json

Save generation.id and query the task until it reaches a terminal state.
This response does not contain the completed video.

objectrequired

The accepted generation and its current processing status.

stringrequired

The generation identifier. Save it to query status and retrieve the result.

Example:: task_xxx

stringrequired

The model used for this generation.

Example:: kling-4-0

stringrequired

The endpoint used for this generation.

Example:: image-to-video

stringrequired

The selected public provider.

Allowed:seeapi

seeapi: SeeAPI

Example:: seeapi

stringrequired

The current generation state. Processing does not mean the video is ready.

Allowed:processing

Example:: processing

numberrequired

The estimated charge in public credits for this request.

Example:: 190.5

numberrequired

Credits consumed by this generation so far.

Example:: 0

numberrequired

Credits refunded for this generation so far.

Example:: 0

string <date-time>required

The time the generation was created, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

string <date-time>required

The time the generation was last updated, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

booleanrequired

Whether this is a replay of an earlier request with the same idempotency key.

Example:: false

200An existing generation was returned for an idempotent replay.

Bodyapplication/json

The same idempotency key and request body return the original generation rather than creating another one.

objectrequired

The accepted generation and its current processing status.

stringrequired

The generation identifier. Save it to query status and retrieve the result.

Example:: task_xxx

stringrequired

The model used for this generation.

Example:: kling-4-0

stringrequired

The endpoint used for this generation.

Example:: image-to-video

stringrequired

The selected public provider.

Allowed:seeapi

seeapi: SeeAPI

Example:: seeapi

stringrequired

The current generation state. Processing does not mean the video is ready.

Allowed:processing

Example:: processing

numberrequired

The estimated charge in public credits for this request.

Example:: 190.5

numberrequired

Credits consumed by this generation so far.

Example:: 0

numberrequired

Credits refunded for this generation so far.

Example:: 0

string <date-time>required

The time the generation was created, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

string <date-time>required

The time the generation was last updated, in ISO 8601 format.

Example:: 2026-08-18T10:00:00Z

booleanrequired

Whether this is a replay of an earlier request with the same idempotency key.

Example:: false

400

Invalid JSON, parameters, Schema, or API Policy

401

Invalid API Key or authentication failed

402

Insufficient credits

403

The current request is not allowed

404

Model, Endpoint, or task not found

409

Idempotency conflict or the same request is still being created

413

Request body is too large

429

Too many requests

503

Service temporarily unavailable