Video

Kling 4.0 API

Kling 4.0 API (kling-v4) unifies text-to-video, image-to-video, multimodal references, video editing and extension. Generate 3–30s clips in 720p or 1080p, always with stereo audio.

Five video modes720p / 1080pStereo audio

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Service Highlights

Official Discounts
Pay-as-you-go
Fast & Low Latency

Input

Model

Prompt *

Resolution

Duration (3–30 seconds)5 seconds

Aspect Ratio

Every video includes a stereo soundtrack.

Output

Kling 4.0 API Pricing

Transparent pricing with no hidden fees. Pay only for what you use.

Variant	Tier	GoldCurrent price	Platinum	Diamond	Official	Your savings
`kling-v4`	720P-input	0.94Credits(~$0.094)/sec	0.893Credits(~$0.0893)/sec	0.846Credits(~$0.0846)/sec	1.175Credits(~$0.1175)/sec	20%
	1080P-input	1.41Credits(~$0.141)/sec	1.3395Credits(~$0.134)/sec	1.269Credits(~$0.1269)/sec	1.7625Credits(~$0.1763)/sec	20%
	720P	1.57Credits(~$0.157)/sec	1.4915Credits(~$0.1492)/sec	1.413Credits(~$0.1413)/sec	1.9625Credits(~$0.1963)/sec	20%
	1080P	2.35Credits(~$0.235)/sec	2.2325Credits(~$0.2233)/sec	2.115Credits(~$0.2115)/sec	2.9375Credits(~$0.2938)/sec	20%

* Actual costs are subject to final output.

Kling 4.0 API for Your Video Workflows

Kling 4.0 API (kling-v4) unifies text-to-video, image-to-video, multimodal references, video editing and extension. Generate 3–30s clips in 720p or 1080p, always with stereo audio.

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Kling 4.0 API Features

Five video workflows share one kling-v4 model ID, with frame control, multimodal references and resolution-based pricing.

Kling 4.0 Text and Image to Video

Generate from a text prompt or a first frame with an optional last frame. Image-to-video can omit the prompt; other modes require it.

Kling 4.0 Keyframe Control

Add up to eight intermediate keyframes in array order. First frame, last frame and keyframes together allow up to ten images.

Kling AI 4.0 Multimodal References

Combine up to ten images, five videos totaling at most 30 seconds, and three audio clips of 5–30 seconds each; at most 15 reference files overall.

Edit Video with Kling 4.0 API

Edit one input video with up to ten reference images. Input must be at least 3 seconds; content beyond 30 seconds is trimmed. Omitted duration and ratio follow the input.

Extend Video with kling-v4

Continue from the last frame for 3–30 new seconds, optionally targeting an end frame. The result combines the original and new clip; only new seconds are billed.

Kling 4.0 Resolution and Stereo Audio

Choose 720p or 1080p and 3–30 whole seconds. Defaults are 720p and 5 seconds. Every output includes a stereo audio track.

Kling 4.0 Aspect Ratios

Use 16:9, 9:16, 1:1 or 21:9. Reference generation also accepts auto; image generation inherits the first frame by default, while extension keeps the source ratio.

Kling 4.0 API Pricing by Workflow

Standard generation bills output seconds. Editing and video references bill output + max(output, input); input seconds are summed, rounded up and capped at 30.

Kling 4.0 Video Workflows

Create, adapt and continue videos with the five Kling 4.0 workflows.

Kling 4.0 Product Concepts

Animate a product image with first- and last-frame control and synchronized sound.

Kling 4.0 Storyboard Planning

Use ordered keyframes to guide the visual progression of a short scene.

Kling AI 4.0 Social Video Ideas

Create portrait or landscape clips, or extend an existing video while keeping its framing.

Kling 4.0 API Integration

Connect asynchronous kling-v4 generation, status queries and result handling to your application.

Kling 4.0 Advertising Concepts

Combine product images, camera-motion references and audio, or edit an existing advertisement.

Kling 4.0 Educational Video Planning

Turn lesson scripts into narrated scenes and extend demonstrations with new footage.

Get Started with the Kling 4.0 API

Create a key, select a workflow and submit your first video task.

Create a Kling 4.0 API Key

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Configure a kling-v4 Request

Choose text, image, reference, edit or extend; add the required prompt and media, then review the live price.

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Integrate Kling 4.0 API

Submit to POST /v1/videos/generations and query GET /v1/tasks/{task_id} until the task finishes.

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Kling 4.0 API Examples

Use model kling-v4 for all five workflows. Submit a video task, then query its video-generation endpoint to obtain the result.

1
Authenticate Kling 4.0 API
Store your key in APIMART_API_KEY and send Authorization: Bearer on each request.
2
Submit a kling-v4 Task
POST /v1/videos/generations with model kling-v4, the prompt and workflow-specific media. Save the returned task ID.
3
Retrieve the Kling 4.0 Result
Query GET /v1/tasks/{task_id} until completion, then retrieve the video result. Check the error details if generation fails.
Check the APIMart documentation for integration updates.

POST /v1/videos/generations

curl -X POST https://api.apimart.ai/v1/videos/generations \
  -H "Authorization: Bearer $APIMART_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kling-v4",
    "prompt": "A cinematic tracking shot of a cyclist riding through a sunlit coastal road, gentle ocean breeze and natural motion",
    "resolution": "720p",
    "duration": 5,
    "aspect_ratio": "16:9"
  }'

import os
import time
import requests

API_BASE = "https://api.apimart.ai"
headers = {"Authorization": f"Bearer {os.environ['APIMART_API_KEY']}"}

# 1. Submit the generation task
payload = {
  "model": "kling-v4",
  "prompt": "A cinematic tracking shot of a cyclist riding through a sunlit coastal road, gentle ocean breeze and natural motion",
  "resolution": "720p",
  "duration": 5,
  "aspect_ratio": "16:9"
}
resp = requests.post(f"{API_BASE}/v1/videos/generations", headers=headers, json=payload, timeout=60)
resp.raise_for_status()
task_id = resp.json()["data"][0]["task_id"]

# 2. Poll the task until it finishes
for _ in range(200):
    task_resp = requests.get(f"{API_BASE}/v1/tasks/{task_id}", headers=headers, timeout=30)
    task_resp.raise_for_status()
    task = task_resp.json()["data"]
    if task["status"] == "completed":
        print(task["result"]["videos"][0]["url"][0])
        break
    if task["status"] == "failed":
        raise RuntimeError(task.get("error", {}).get("message", "generation failed"))
    time.sleep(10)
else:
    raise TimeoutError(f"task {task_id} did not finish in time")

curl -X POST https://api.apimart.ai/v1/videos/generations \
  -H "Authorization: Bearer $APIMART_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kling-v4",
    "prompt": "Animate this scene with a slow camera push-in, subtle natural movement and consistent composition",
    "resolution": "720p",
    "duration": 5,
    "image_urls": [
      "https://example.com/first-frame.jpg"
    ]
  }'

TASK_ID="task_xxx"  # replace with the task_id returned by the POST request
curl "https://api.apimart.ai/v1/tasks/$TASK_ID" \
  -H "Authorization: Bearer $APIMART_API_KEY"

Kling 4.0 API Parameters

Parameter	Type	Required	Default	Description
`model`	string	Required	Default: kling-v4	Fixed model ID: kling-v4.
`prompt`	string	Optional	Default: —	Required except for image-to-video, where it may be omitted.
`duration`	integer	Optional	Default: 5	3–30 whole seconds; default 5. For editing, omission follows the input duration. For extension, this is the new clip length.
`resolution`	string	Optional	Default: 720p	720p or 1080p; default 720p.
`aspect_ratio`	string	Optional	Default: —	16:9, 9:16, 1:1 or 21:9; reference mode also accepts auto. Defaults: text 16:9, image follows first frame, reference auto, edit follows source. Omit for extension.
`image_urls`	string[]	Optional	Default: —	Image mode: first frame then optional last frame, at most two. Explicit reference mode and editing: up to ten reference images.
`image_with_roles`	object[]	Optional	Default: —	Objects with url and role: first_frame, last_frame, keyframe or reference_image. Up to eight keyframes and ten frame images total; middle_frame is also accepted.
`first_frame_image`	string	Optional	Default: —	First-frame image URL for image-to-video.
`last_frame_image`	string	Optional	Default: —	Last-frame image URL; in extension, the target end frame.
`video_urls`	string[]	Optional	Default: —	Reference videos: up to five and 30 seconds in total. Editing or extension also accepts one entry instead of video_url.
`video_url`	string	Optional	Default: —	One source video for edit or extend; set omni_reference_task_type explicitly. Editing requires at least 3 seconds and trims beyond 30.
`audio_urls`	string[]	Optional	Default: —	Up to three reference audio clips, each 5–30 seconds. Images, videos and audio together must not exceed 15 files.
`omni_reference_task_type`	string	Optional	Default: auto	auto, reference, edit or extend. A standalone video_url requires edit or extend. Explicit reference treats image_urls as reference images.
`audio_setting`	string	Optional	Default: —	origin keeps source audio; auto regenerates it. Available for editing and reference mode with video. Editing defaults to origin, reference to auto. Omit for extension.

Kling API Model Family

Compare Kling video models on APIMart. Check each model’s availability, capabilities and pricing on its own page.

Model	Best for	Resolution	Duration
Kling 4.0 APIThis page	Text, frame and multimodal generation, video editing and extension, always with stereo audio	720P / 1080P	3–30 s
Kling 3.0 API	Cinematic text-to-video and image-to-video with first/last-frame control and multi-shot prompts	720P / 1080P / 4K	3–15 s
Kling 3.0 Omni API	All-in-one generation from text, images and video, with reference roles and video editing	720P / 1080P / 4K	3–15 s
Kling 3.0 Turbo API	Speed-optimized text-to-video and first-frame image-to-video	720P / 1080P	3–15 s
Kling Video O1 API	Thinking-driven generation focused on visual fidelity	720P / 1080P	5 s / 10 s
Kling 2.6 API	Native audio (pro mode), dynamic masks and camera control	720P / 1080P	5 s / 10 s
Kling Motion Control 2.6 API	Transfer motion from a reference video onto the subject of your image	720P / 1080P	Follows reference video
Kling 3.0 Motion Control API	Newer V3 generation of reference-video motion transfer	720P / 1080P	Follows reference video

Kling 4.0 API FAQ

Modes, reference limits, pricing, audio and API integration.

What is Kling 4.0 API and how are its modes selected?

Kling 4.0, also called Kling AI 4.0 or Kling4.0, uses model ID kling-v4. Text-only requests generate from text; a first frame selects image mode; reference images, video_urls or audio_urls select reference mode. Set omni_reference_task_type to edit or extend with video_url for those workflows. Kling 4.0 Flash has a separate page.

What reference limits does Kling 4.0 support?

Image mode requires one first frame and allows one last frame plus up to eight keyframes, with ten frame images total. Reference mode allows ten images, five videos totaling 30 seconds, and three audio clips of 5–30 seconds each, up to 15 files combined. Address them as @Image1, @Video1 and @Audio1 in the prompt.

How is Kling 4.0 API billed?

Text, image, image/audio-only reference generation and extension use output seconds; extension counts only newly generated footage. Editing and reference generation with video use output + max(output, input) at the video-input rate. Input duration is summed, rounded up and capped at 30 seconds. Editing a 3.04-second video without duration produces 4 seconds and bills 8 seconds. Check the live rates on this page. Failed generations are fully refunded; input-duration probe failures return 400 without charge.

Which output and audio settings does Kling 4.0 offer?

Outputs are 720p or 1080p, 3–30 seconds, and always include stereo audio. Text defaults to 16:9, image to the first-frame ratio, reference to auto and editing to the source ratio. Explicit ratios are 16:9, 9:16, 1:1 and 21:9; auto is reference-only. Editing keeps original sound by default; audio_setting auto regenerates it. Reference mode with video can use origin to keep its sound.

How do I call Kling 4.0 API and retrieve a result?

Submit POST /v1/videos/generations with model kling-v4, then query GET /v1/tasks/{task_id}. Media must be publicly accessible. Use resolution instead of mode; V3 fields such as multi_shot, multi_prompt, element_list and negative_prompt are unsupported, as is audio false.

Does Kling 4.0 extension return only the new clip?

No. Extension adds 3–30 seconds after the input’s last frame and returns the original video joined to the new footage. Only new output seconds are billed. You can specify a target last_frame_image or last_frame role. Do not send aspect_ratio or audio_setting; framing is inherited, original audio is preserved and new audio is generated.

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Kling 4.0 API

Kling 4.0 API Pricing

Kling 4.0 API for Your Video Workflows

Kling 4.0 API Features

Kling 4.0 Video Workflows

Get Started with the Kling 4.0 API

Create a Kling 4.0 API Key

Configure a kling-v4 Request

Integrate Kling 4.0 API

Kling 4.0 API Examples

Authenticate Kling 4.0 API

Submit a kling-v4 Task

Retrieve the Kling 4.0 Result

Kling 4.0 API Parameters

Kling API Model Family

Kling 4.0 API FAQ

What is Kling 4.0 API and how are its modes selected?

What reference limits does Kling 4.0 support?

How is Kling 4.0 API billed?

Which output and audio settings does Kling 4.0 offer?

How do I call Kling 4.0 API and retrieve a result?

Does Kling 4.0 extension return only the new clip?

Related Models

Kling 4.0 API Features

Kling 4.0 Video Workflows

Get Started with the Kling 4.0 API

Create a Kling 4.0 API Key

Configure a kling-v4 Request

Integrate Kling 4.0 API

Kling 4.0 API FAQ

What is Kling 4.0 API and how are its modes selected?

What reference limits does Kling 4.0 support?

How is Kling 4.0 API billed?

Which output and audio settings does Kling 4.0 offer?

How do I call Kling 4.0 API and retrieve a result?

Does Kling 4.0 extension return only the new clip?

Related Models