How to Use the Kling 4.0 Image to Video API: image to video integration guide (2026)
Learn how to call the Kling 4.0 Image to Video API on NamiFusion: parameters, pricing (from ≈$0.785) and runnable copy-paste code — try it in the playground first.
Kling 4.0 Image to Video is an image to video model by Kling: Animate a first frame with optional last and ordered middle frames; up to 10 frames in total, 3–30 seconds, 720p or 1080p. On NamiFusion you can try it in the playground (exact quote shown before you submit), then call it through one unified REST API — about $0.785 per typical run.
TL;DR
· Task type: image to video, provided by Kling
· Pricing: about $0.785 per typical run ($1 = 100 credits), pay-as-you-go
· Getting started: playground (exact quote before submit) → create an API key → one POST request
· Tunable parameters: 7 (see the table below)
· No platform watermark; commercial use allowed (per the Terms of Service)
What can you build with Kling 4.0 Image to Video?
Short-form video and ad clips: go from a prompt or a single image to publishable motion content.
Product demos and concept previews: validate storyboards and visual direction cheaply before any shoot.
A social content factory: batch vertical clips and ride trending topics fast.
Remixing existing assets: image-to-video brings static work to life and extends its lifespan.
How do you call this API?
- Sign up on NamiFusion and create a key on the API Keys page (signup bonus credits can only be used on selected models).
- Submit a task with the cURL example below, passing your key as a Bearer token.
- Poll the task status with the returned task_uuid and read the output URLs when completed.
# 1) Submit — returns { "task_uuid": "..." }
curl -X POST "https://www.namifusion.com/api/v1/marketplace/run/kwaivgi/kling-v4.0/image-to-video" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"input": {
"image": "https://example.com/input.jpg",
"resolution": "720p",
"duration": 5
}
}'
# 2) Poll until status is "completed", then read the output URLs
curl "https://www.namifusion.com/api/v1/marketplace/run/tasks/TASK_UUID" \
-H "Authorization: Bearer YOUR_API_KEY"What parameters does it take?
image (Start frame): required
prompt (Prompt): optional
last_image (Last frame): optional
keyframes (Ordered middle frames): optional
resolution (Resolution): optional, default "720p"
duration (Duration): optional, default 5
aspect_ratio (Aspect ratio): optional
How do you write prompts for Kling 4.0 Image to Video?
- Subject first: lead with the actor and action, then add environment, lighting and style ("an astronaut sprinting through a neon street in the rain, cinematic, shallow depth of field").
- Concrete nouns beat stacked adjectives: "85mm portrait lens, golden-hour backlight" works far better than "very beautiful, ultra high quality".
- Change one variable per iteration: pin the seed to reproduce a result, tweak a single phrase at a time so you know what actually moved the output.
- State negatives positively: instead of "no blur", ask for "sharp focus, crisp details".
How much does it cost?
Pay-per-use in credits. About $0.785 per typical run ($1 = 100 credits); the exact price varies with parameters like resolution or duration, and the playground shows the exact quote before you submit.
Kling 4.0 Image to Video
Animate a first-frame image into a 3–30 second video with native stereo audio. An optional last frame and ordered middle frames guide the progression.
Inputs
- image: required URL array containing exactly one first-frame image. Use JPG, JPEG or PNG.
- prompt: optional string; may be omitted or empty.
- last_image: optional URL array with at most one last-frame image.
- keyframes: optional ordered image-URL array, at most 9 items; at most 8 when last_image is supplied.
- resolution: "720p" (default) or "1080p".
- duration: integer from 3 through 30, default 5.
- aspect_ratio: optional "16:9", "9:16", "1:1" or "21:9". Omit to follow the first image; do not send "auto".
Limits and references
The first image, last image and keyframes together must not exceed 10 images. Middle frames are used in array order. Describe motion and sound in prompt; no separate sound toggle is exposed.
List price and initial credit charge
720p: $0.157 per output second. 1080p: $0.235 per output second.
Cost = output seconds × resolution rate. A 5-second clip costs $0.785 at 720p or $1.175 at 1080p.
1 USD = 100 Nami credits. Round the total charge upward to 0.01 credit: credits = ceil(cost_usd × 10000) / 100. These are list prices; no promotional discount is applied.
First, last and middle images do not add separate charges.
FAQ
Can I try it for free first?+
Signup bonus credits can only be used on selected models, and eligibility may change. The playground shows the exact quote before submission.
Can I use the output commercially? Is there a watermark?+
Yes, outputs are yours to use commercially, and NamiFusion adds no platform watermark — subject to the Terms of Service and applicable law.
What is the content policy?+
Pornographic content, sexualized content involving a minor, unauthorized use of real people, deceptive impersonation, fraud and false endorsements are prohibited. Lawful, consensual, non-explicit adult themes may be permitted; see the Terms of Service.
How long does a Kling 4.0 Image to Video task take?+
It depends on parameters — images usually take seconds, videos tens of seconds to minutes. The API returns a task_uuid for polling.
What are the resolution and duration limits?+
See the parameter table above — each model lists its available resolution and duration options there and in the playground.