How to Generate Kling 4.0 Video via the Kling API

5 min read • October 18, 2026

Table of contents

  1. Introduction
  2. Before you start
  3. Kling 4.0 at a glance
  4. Generate a Kling 4.0 video in two calls
    1. 1. Submit the job
    2. 2. Poll for the result
    3. 3. Download the master
  5. Longer, wider and 1080p
  6. Image-to-video with keyframes
  7. Omni with references and voices
  8. Batch-generate with the script
  9. What it costs
  10. The same from an AI assistant
  11. Examples
  12. Frequently asked questions
  13. Conclusion

Introduction

Kling 4.0 launched in the Kling app on October 15, 2026, and Kling’s own developer API still lists it as coming soon, so the way to call it from code today is the useapi.net Kling API: send "model_name": "kling-v4-0" to POST /videos/text2video and it runs on your own Kling account. useapi.net is a third-party API, not affiliated with Kling AI or Kuaishou Technology. Kling 4.0 makes 3 to 30 second clips at 720p or 1080p, always with a stereo soundtrack, and adds the 21:9 aspect ratio and keyframes between the start and end frames.

This guide is one real run. We asked Kling 4.0 for the cheapest clip it makes, 3 seconds at 720p, on a Kling Pro plan account. The job finished in about 2 minutes and took 27 Kling credits off the balance (300,290 to 297,590 in the account’s hundredths of a credit), about $0.30 at the Pro plan’s credit price. Every response below is from that run, with the account email left out.

Before you start

You need a useapi.net API token and a Kling account connected through Setup Kling. Kling 4.0 at 1080p needs a paid Kling plan. Export the token so the curl examples run as they are:

export USEAPI_TOKEN="user:1234-..."      # your useapi.net API token
export KLING_EMAIL="[email protected]"     # your connected Kling account

email can be left out of the request body when you have only one Kling account connected. If Kling hasn’t opened Kling 4.0 to your account yet, the create call returns 403 with AUTH.VPrivilegeEscalation, and nothing is charged.

Kling 4.0 at a glance

  Kling 4.0 (kling-v4-0)
Duration 3 to 30 seconds, default 5
Resolution std 720p, pro 1080p (paid Kling plan). No 4K or HDR yet
Aspect ratio 16:9, 9:16, 1:1, 21:9
Audio Always on, stereo
Prompt Up to 8000 characters
Shots Kling may cut the clip into several shots, or you write up to 6 shot prompts (15 seconds in total)
Credits per second 10 at 720p, 15 at 1080p (Kling Pro and Ultra subscribers pay 10% less)

The same model is on three endpoints: text-to-video, image-to-video with start, end and keyframe images, and Omni with reference images, elements, videos and voices. The credit price is the same on all three.

Generate a Kling 4.0 video in two calls

Generation is asynchronous. The create call answers right away with a task, and you poll the task until it is final.

1. Submit the job

POST /videos/text2video with model_name set to kling-v4-0:

curl -s -X POST "https://api.useapi.net/v1/kling/videos/text2video" \
  -H "Authorization: Bearer $USEAPI_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "'"$KLING_EMAIL"'",
    "model_name": "kling-v4-0",
    "mode": "std",
    "duration": "3",
    "aspect_ratio": "16:9",
    "prompt": "A small paper boat sails across a rain puddle on a city sidewalk at dusk, neon signs reflect and ripple in the water, raindrops patter around it and a tram bell rings in the distance, low camera at water level"
  }'

The answer came back in about a second. The parts that matter, from our run:

{
  "task": {
    "id": 324332112308198,
    "type": "m2v_aio2video",
    "status": 5,
    "status_name": "submitted",
    "status_final": false
  },
  "works": [],
  "status": 5,
  "status_name": "submitted",
  "status_final": false,
  "message": "",
  "userPoints": {
    "points": [],
    "total": 297590
  }
}

task.id is the id you poll. userPoints.total is the balance after the charge, in hundredths of a credit, so 297590 is 2,975.90 credits. The task’s arguments echo what Kling received: kling_version 4.0, model_mode std, enable_audio true and prefer_multi_shots true. Kling 4.0 always turns audio on, and it may cut the clip into shots on its own. The create call is the paid step, so don’t resend it after a timeout. Poll or list your tasks instead.

2. Poll for the result

GET /tasks/task_id:

curl -s "https://api.useapi.net/v1/kling/tasks/324332112308198?email=$KLING_EMAIL" \
  -H "Authorization: Bearer $USEAPI_TOKEN"

Ours read processing for about 2 minutes, then:

{
  "status": 99,
  "status_name": "succeed",
  "status_final": true,
  "works": [
    {
      "workId": 324332112317252,
      "status_name": "succeed",
      "resource": {
        "resource": "https://v15-kling.klingai.com/bs2/upload-ylab-stunt-sgp/....mp4",
        "height": 720,
        "width": 1280,
        "duration": 3041
      }
    }
  ]
}

The MP4 is 1280×720, 3.04 seconds, H.264 video with a two-channel AAC soundtrack. A task is done when status_final is true, and status_name: "succeed" means it worked. The other final statuses are failures, listed on GET /tasks/task_id. Pass a replyUrl in the create body if you’d rather get a webhook than poll.

3. Download the master

Free Kling plans get a watermarked works[0].resource.resource. On a paid plan, GET /assets/download returns a cdnUrl to the clean file:

curl -s "https://api.useapi.net/v1/kling/assets/download?email=$KLING_EMAIL&workIds=324332112317252&fileTypes=MP4" \
  -H "Authorization: Bearer $USEAPI_TOKEN"

Longer, wider and 1080p

Change three fields and keep the rest. A 10-second 1080p cinema-wide clip:

{
  "model_name": "kling-v4-0",
  "mode": "pro",
  "duration": "10",
  "aspect_ratio": "21:9",
  "prompt": "..."
}

That costs 150 credits (15 per second), or 135 on a Kling Pro or Ultra plan. duration goes up to 30. To direct the cuts yourself, send shot_1_prompt with shot_1_duration, shot_2_prompt with shot_2_duration and so on, up to 6 shots and 15 seconds in total, in place of prompt and duration. negative_prompt and cfg_scale don’t apply to Kling 4.0.

Image-to-video with keyframes

POST /videos/image2video-frames with model_name: kling-v4-0 takes a start frame (image, required), an optional end frame (image_tail) and up to 9 keyframes in between (keyframe_1 to keyframe_9), in order. That is up to 10 images in total, and at most the duration in seconds plus one, so a 5-second clip takes up to 6 images. Upload each image with POST /assets first and pass the returned URLs:

curl -s -X POST "https://api.useapi.net/v1/kling/videos/image2video-frames" \
  -H "Authorization: Bearer $USEAPI_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "email": "'"$KLING_EMAIL"'",
    "model_name": "kling-v4-0",
    "mode": "std",
    "duration": "5",
    "image": "https://example.com/start.jpg",
    "keyframe_1": "https://example.com/middle.jpg",
    "image_tail": "https://example.com/end.jpg",
    "prompt": "the boat drifts from the puddle into the gutter stream"
  }'

The aspect ratio comes from the start image. You poll and download the result the same way as above.

Omni with references and voices

POST /videos/omni with omni_version: v4 runs Kling 4.0 with up to 10 reference images, 7 elements (IMAGE and VIDEO), 5 reference videos of 3 to 30 seconds each (30 seconds in total) and 3 voices, including your own voice saved with POST /videos/voices. Reference them in the prompt as @image_1, @video_1 or @voice_1. Omni 4.0 doesn’t take start and end frames, so use image-to-video above for those. The Kling Omni tutorial walks through the reference workflows.

Batch-generate with the script

The kling-4 example in the kling-api GitHub repo reads Kling 4.0 prompts from prompts.json (text-to-video, 21:9 and multi-shot) or prompts-frames.json (start, end and keyframe images), checks each one against the documented limits before it spends credits, submits it, polls the task and downloads the clean master. Run it with Node.js v21 or newer:

git clone https://github.com/useapi/kling-api.git
cd kling-api/kling-4
node ./kling4.mjs "$USEAPI_TOKEN" "$KLING_EMAIL"

The Kling v3 tutorial explains the script line by line.

What it costs

Kling 4.0 draws from your Kling account’s own credits: 10 per second at 720p and 15 per second at 1080p, and Kling Pro and Ultra subscribers pay 10% less. Our 3-second 720p clip cost 27 credits on a Pro plan. A 5-second 720p clip is 50 credits, or 45 on Pro, so the Pro plan’s 3,000 monthly credits ($33) cover about 66 of them. On top of the Kling plan, useapi.net is a flat $15/month for every API it offers, with no per-generation charge. The cost calculator on the Kling API page converts credits to dollars for each Kling plan.

Kling’s own developer API sells API units separately from the Kling app plans. See How much does the Kling API cost? for how the two compare.

The same from an AI assistant

The hosted Kling MCP server at https://api.useapi.net/v1/kling/mcp exposes the same calls as 45 tools for Claude Code, Cursor and VS Code, Kling 4.0 included. Ask for “a 5-second Kling 4.0 clip of …” and the assistant calls kling_text_to_video with model_name: kling-v4-0 on your account.

Examples

Kling 4.0 » kling-v4-0, text-to-video, std 720p, 3 seconds, 16:9, the run above

The prompt is in step 1. 27 Kling credits on a Pro plan, about 2 minutes, with its stereo soundtrack.

Frequently asked questions

Is there a Kling 4.0 API? Yes, through useapi.net: the third-party useapi.net Kling API already runs it, kling-v4-0 on text-to-video and image-to-video and omni_version: v4 on Omni, on your own Kling account. Kling’s own developer API listed Kling 4.0 as coming soon when this was written (October 18, 2026).

What is the model name for Kling 4.0? kling-v4-0 on POST /videos/text2video and POST /videos/image2video-frames, and omni_version: v4 on POST /videos/omni.

Does Kling 4.0 need a paid Kling plan? 1080p (mode: pro) does. A 403 with AUTH.VPrivilegeEscalation means Kling hasn’t opened the model to that account yet.

Can I turn audio off? No. Kling 4.0 always generates stereo audio and doesn’t accept enable_audio.

How long can a Kling 4.0 video be? 3 to 30 seconds per generation. Kling v3 stops at 15 seconds.

Do I need a Kling developer account or API key? No. You need a useapi.net API token and a Kling account connected through Setup Kling.

Conclusion

Kling 4.0 is one field away from any Kling call you already make: set model_name to kling-v4-0 and pick a duration up to 30 seconds. The full model reference is on the Kling API page, and the runnable code is in the kling-api GitHub repo.

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