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kwaivgi/kling-v4.0/text-to-video

Kling V4.0 Text-to-Video generates cinematic clips of 3 to 30 seconds from a text prompt, with 720p and 1080p output, four aspect ratios including 21:9 ultrawide, and synchronized stereo audio. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing.

Text to Video
Input

Idle

$0.785per run·~12 / $10

Next:

ExamplesView all

A young royal chef stands inside a huge medieval castle kitchen, wearing a cream tunic and dark leather apron while dozens of elaborate dishes cover a long wooden table. A small dragon suddenly pushes its head through an open stone window. Everyone in the kitchen freezes. The chef cautiously offers it a roasted chicken. The dragon ignores it completely. He nervously raises a tiny fruit tart instead. The dragon’s eyes immediately brighten and it gently reaches toward the dessert. The camera begins behind hanging copper pans, tracks toward the chef, then pushes past him toward the dragon outside the window. Playful Western fantasy, detailed medieval kitchen, expressive creature behavior, cinematic comedy, realistic food and firelight.

A fisherman in a yellow raincoat rows a small wooden boat across a calm misty lake at dawn, soft golden light breaking through the fog, gentle ripples, a heron lifts off in the background, slow cinematic dolly-in, natural ambient sound of water and distant birds

Related Models

README

Kling V4.0 Text-to-Video

Kling V4.0 Text-to-Video is Kuaishou's flagship video model: describe a scene and get a cinematic clip of 3 to 30 seconds in a single pass, with synchronized stereo audio. Output is 720p or 1080p in 16:9, 9:16, 1:1 or 21:9.

Why Choose This?

  • Long single takes Any length from 3 to 30 seconds in one generation, with room for real action and camera movement.
  • Ultrawide option 21:9 alongside 16:9, 9:16 and 1:1.
  • Native audio Stereo sound is generated together with the picture.
  • Simple pricing Pay per second of output, by resolution.

Pricing

ResolutionPrice per second
720p$0.157
1080p$0.235

The price is per second of the generated video (for example a 5 second 720p clip costs $0.785).

Parameters

ParameterDescription
promptText describing the video.
resolution720p (default) or 1080p.
duration3 to 30 seconds, default 5.
aspect_ratio16:9 (default), 9:16, 1:1 or 21:9.

Prompting Guide

  • Name the subject, the action, the setting and the camera movement ("slow dolly-in", "handheld tracking shot").
  • Describe sound you want to hear (ambience, music, a line of dialogue) in the prompt.
  • For longer clips, describe how the scene develops from beginning to end.
Note:This website uses AI models provided by third parties. Documentation prices are for reference and may be outdated. The Generate button shows an estimate; the final task charge prevails.

Kling v4.0 Text To Video API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0/text-to-video with your input as JSON. The endpoint returns a prediction id. Start polling the result endpoint around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. On completed, read output values from data.outputs. Examples for Kling v4.0 Text To Video below.

HTTP example
set -euo pipefail

: "${WAVESPEED_API_KEY:?Set WAVESPEED_API_KEY}"

REQUEST_BODY=$(cat <<'JSON'
{
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "resolution": "720p",
    "duration": 5,
    "aspect_ratio": "16:9"
}
JSON
)

# 1. Submit the prediction.
SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  -X POST "https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0/text-to-video" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY" \
  -d "$REQUEST_BODY")

TASK=$(printf '%s' "$SUBMIT_RESPONSE" | jq 'if has("data") then .data else . end')
PREDICTION_ID=$(printf '%s' "$TASK" | jq -r '.id')
if [ -z "$PREDICTION_ID" ] || [ "$PREDICTION_ID" = "null" ]; then
  printf 'Submission response did not contain a prediction id
' >&2
  exit 1
fi
RESULT_URL="https://api.wavespeed.ai/api/v3/predictions/$PREDICTION_ID/result"

# 2. Poll until the prediction finishes.
while true; do
  RESPONSE=$(curl --silent --show-error --fail-with-body "$RESULT_URL" \
    -H "Authorization: Bearer $WAVESPEED_API_KEY")
  RESULT=$(printf '%s' "$RESPONSE" | jq 'if has("data") then .data else . end')
  STATUS=$(printf '%s' "$RESULT" | jq -r '.status')
  case "$STATUS" in
    completed) printf '%s\n' "$RESULT" | jq '.outputs'; break ;;
    failed|cancelled|timeout|deleted) printf '%s\n' "$RESULT" | jq . >&2; exit 1 ;;
    *) sleep 2 ;;
  esac
done
Node.js example
const submitUrl = "https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0/text-to-video";
const apiKey = process.env.WAVESPEED_API_KEY;
if (!apiKey) throw new Error('Set WAVESPEED_API_KEY');

async function requestJson(url, options = {}) {
  const response = await fetch(url, options);
  if (!response.ok) throw new Error(await response.text());
  return response.json();
}

// 1. Submit the prediction.
const body = await requestJson(submitUrl, {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
        "prompt": "A cinematic shot of a city at sunset, soft golden light",
        "resolution": "720p",
        "duration": 5,
        "aspect_ratio": "16:9"
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = `https://api.wavespeed.ai/api/v3/predictions/${task.id}/result`;

// 2. Poll until the prediction finishes.
while (true) {
  const resultBody = await requestJson(resultUrl, {
    headers: { "Authorization": `Bearer ${apiKey}` },
  });
  const result = resultBody.data ?? resultBody;
  if (result.status === "completed") {
    console.log(result.outputs);
    break;
  }
  if (["failed", "cancelled", "timeout", "deleted"].includes(result.status)) throw new Error(JSON.stringify(result));
  await new Promise(resolve => setTimeout(resolve, 2000));
}
Python example
import json
import os
import time
from urllib.request import Request, urlopen

api_key = os.environ["WAVESPEED_API_KEY"]
headers = {"Authorization": f"Bearer {api_key}", "Content-Type": "application/json"}
payload = {
    "prompt": "A cinematic shot of a city at sunset, soft golden light",
    "resolution": "720p",
    "duration": 5,
    "aspect_ratio": "16:9"
}

def request_json(url, data=None):
    request = Request(url, data=data, headers=headers, method="POST" if data else "GET")
    with urlopen(request) as response:
        return json.load(response)

# 1. Submit the prediction.
body = request_json("https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0/text-to-video", json.dumps(payload).encode())
task = body.get("data", body)
if not task.get("id"):
    raise RuntimeError("Submission response did not contain a prediction id")
result_url = f"https://api.wavespeed.ai/api/v3/predictions/{task['id']}/result"

# 2. Poll until the prediction finishes.
while True:
    result_body = request_json(result_url)
    result = result_body.get("data", result_body)
    status = result.get("status")
    if status == "completed":
        print(result.get("outputs", []))
        break
    if status in {"failed", "cancelled", "timeout", "deleted"}:
        raise RuntimeError(result)
    time.sleep(2)

Kling v4.0 Text To Video API — Frequently asked questions

What is the Kling v4.0 Text To Video API?

Kling v4.0 Text To Video is a Kuaishou model for video generation, exposed as a REST API on WaveSpeedAI. Kling V4.0 Text-to-Video generates cinematic clips of 3 to 30 seconds from a text prompt, with 720p and 1080p output, four aspect ratios including 21:9 ultrawide, and synchronized stereo audio. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing. You can call it programmatically or try it from the playground above.

How do I call the Kling v4.0 Text To Video API?

POST your input parameters to the model's REST endpoint (shown in the API tab of this playground) with your WaveSpeedAI API key in the Authorization header. Submission returns a prediction ID. Poll the result endpoint starting around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. The playground generates Python, JavaScript, and cURL examples for submitting requests and polling results. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/kwaivgi/kwaivgi-kling-v4.0-text-to-video.

How much does Kling v4.0 Text To Video cost per run?

Kling v4.0 Text To Video starts at $0.785 per run. That figure is the base price — the final charge scales with the parameters you set in the form (output size, length, count, references, or whatever knobs this model exposes), so a higher-quality or larger output costs more than a minimal one. The exact cost for your current input is shown live next to the Generate button before you submit, and the actual per-call charge is recorded on the prediction afterwards.

What inputs does Kling v4.0 Text To Video accept?

Key inputs: `prompt`, `aspect_ratio`, `resolution`, `duration`. The full JSON schema (types, defaults, allowed values) is rendered above the Generate button and mirrored in the API reference at https://wavespeed.ai/docs/docs-api/kwaivgi/kwaivgi-kling-v4.0-text-to-video.

How do I get started with the Kling v4.0 Text To Video API?

Sign up for a free WaveSpeedAI account to claim starter credits, copy your API key from /accesskey, then call the endpoint shown in the API tab of the playground. The playground also auto-generates a code sample in Python, JavaScript, or cURL for the parameters you've set.

Can I use Kling v4.0 Text To Video outputs commercially?

Commercial usage rights depend on the model's license, set by its provider (Kuaishou). Check the provider's applicable terms and WaveSpeedAI's Terms of Service before commercial use.

llms.txt — kwaivgi/kling-v4.0/text-to-video for AI agents and LLMs