Video Image to Video Kie.ai

Kling 4.0 Keyframes

Kling 4.0 Keyframes costs $0.171/s (720p) on FairStack · an image to video model for Storyboard-to-shot animation, Product reveals with fixed start and end, Multi-beat scenes in one take. No subscription required. Pay per generation with full REST API access. FairStack applies a transparent 20% margin on infrastructure cost so you always see the real price.

FairStack price

$0.171/s

720p

Platform fee

Flat 20%

Try Kling 4.0 Keyframes API Quickstart Last updated 2026-11-10

What is Kling 4.0 Keyframes?

Kling 4.0 Keyframes animates from your images. Give it a first frame, optionally a last frame, and up to 8 middle keyframes in order, and it moves through them in one continuous shot. Name them in the prompt as @first_frame, @keyframe_1, @keyframe_2 and @last_frame to say what happens at each. The number of frames depends on the length: a 3-second clip takes up to 4 frames, a 5-second clip 6, and 9 seconds or longer the full 10. Output follows the first frame's aspect ratio, at 720p or 1080p, from 3 to 30 seconds. Priced per second of output at the resolution you pick: the provider's rate plus a flat 20% platform fee, shown before you spend.

Key Features

First frame, last frame and up to 8 middle keyframes

Frames named in the prompt (@first_frame, @keyframe_1, @last_frame)

3 to 30 seconds, 720p or 1080p

Output keeps the first frame's aspect ratio

What are Kling 4.0 Keyframes's strengths?

Multi-beat shots that visit each keyframe in order

Controlled start and end states

Long takes up to 30s

What are Kling 4.0 Keyframes's limitations?

Frames allowed depend on the length (3s: 4 frames, 9s+: 10)

Aspect ratio follows the first frame

What is Kling 4.0 Keyframes best for?

Storyboard-to-shot animation Product reveals with fixed start and end Multi-beat scenes in one take

How much does Kling 4.0 Keyframes cost?

Metric

FairStack

Details

720p(default)

$0.171/s

Billed per second, 20% platform fee included.

1080p

$0.255/s

Billed per second, 20% platform fee included.

Subscription

None

Pay per generation only

How does Kling 4.0 Keyframes perform across capabilities?

Estimated from the Kling 4.0 launch notes, not benchmark-verified (PRD-1229)

motion quality

90%

visual quality

89%

prompt adherence

85%

temporal coherence

90%

character consistency

88%

camera control

84%

How do I use the Kling 4.0 Keyframes API?

curl

curl -X POST https://api.fairstack.ai/v1/generations/video \
  -H "Authorization: Bearer $FAIRSTACK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kling-4-0-i2v",
    "input": {
      "prompt": "Your prompt here",
      "image_url": "https://example.com/photo.jpg"
    }
  }'

Python

import os
import requests

response = requests.post(
    "https://api.fairstack.ai/v1/generations/video",
    headers={
        "Authorization": f"Bearer {os.environ['FAIRSTACK_API_KEY']}",
        "Content-Type": "application/json",
    },
    json={
      "model": "kling-4-0-i2v",
      "input": {
        "prompt": "Your prompt here",
        "image_url": "https://example.com/photo.jpg"
      }
    },
)

result = response.json()
print(result["data"])

Node.js

const response = await fetch("https://api.fairstack.ai/v1/generations/video", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.FAIRSTACK_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "kling-4-0-i2v",
    "input": {
      "prompt": "Your prompt here",
      "image_url": "https://example.com/photo.jpg"
    }
  }),
});

const result = await response.json();
console.log(result.data);

What parameters does Kling 4.0 Keyframes support?

Parameter

Type

Default

Details

resolution

enum

720p

Options: 720p, 1080p

duration

integer

Range: 3–30

keyframe_urls

array_of_strings (optional)

—

Frequently Asked Questions

How much does Kling 4.0 Keyframes cost?

Kling 4.0 Keyframes costs $0.171/s (720p) on FairStack as of 2026-11-10. This price includes FairStack's transparent 20% margin on infrastructure cost. No subscription or monthly fee — you pay per generation only. Minimum deposit is $1.

What is Kling 4.0 Keyframes and what is it best for?

Does Kling 4.0 Keyframes have an API?

Yes. Kling 4.0 Keyframes is available via FairStack's REST API at api.fairstack.ai. Send a POST request to /v1/generations/video with your API key, the model key, and an input object (input.prompt). Works with curl, Python requests, Node.js fetch, and any HTTP client. No SDK installation required.

How does Kling 4.0 Keyframes compare to other video models?

Kling 4.0 Keyframes excels at Storyboard-to-shot animation, Product reveals with fixed start and end, Multi-beat scenes in one take. It is an image to video model priced at $0.171/s (720p) on FairStack. Key strengths: Multi-beat shots that visit each keyframe in order, Controlled start and end states. Compare all video models at fairstack.ai/models.