How much does Kling 4.0 Flash cost on varg?

Kling 4.0 Flash costs from $0.38 per run on varg ($0.126/s on the cheapest route). varg charges the provider's price with no markup, from one credit balance. For the exact price of a request before you run it, send the same body to POST https://api.varg.ai/v2/estimate.

How do I call the Kling 4.0 Flash API?

Send POST https://api.varg.ai/v2/tools/video/call with the header "Authorization: Bearer $VARG_API_KEY" and a JSON body that includes "model": "kling_v4_flash". The call answers 202 with a job right away. Poll GET https://api.varg.ai/v2/jobs/{id} until "status" is "completed", then read output.outputs[0].url, or pass options.webhook_url to be called back.

Can I use Kling 4.0 Flash from Claude, ChatGPT or Cursor?

Yes. Add the varg MCP server (https://mcp.varg.ai/mcp) to Claude, ChatGPT, Cursor or any other MCP client and sign in with varg, with no API key to paste. The agent runs Kling 4.0 Flash with call_tool, passing tool "video" and "model": "kling_v4_flash".

How long does a Kling 4.0 Flash request take?

Typically about 2 min on the fastest route, by the catalog's estimate. The API answers at once with a job id, so nothing waits on an open connection while it runs.

Video · Text to video · Image to video · Video to video

Kling 4.0 Flash API

Kling 4.0 Flash by Kuaishou. Fast 720p drafts up to 20 seconds from text, a start frame or reference elements.

Price: From $0.38 per run $0.126/s
Typical time: ~2 min
Model id: kling_v4_flash

Kling 4.0 Flash runs on one varg API key and one credit balance, the same as every other model here. You pay the provider's price, with no markup.

POST /v2/tools/video/call

curl -X POST https://api.varg.ai/v2/tools/video/call \
  -H "Authorization: Bearer $VARG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "kling_v4_flash",
  "prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope.",
  "duration": 5
}'

Try it in the Playground Get an API key

Kling 4.0 Flash pricing

From $0.38 per run. Prices are in US dollars and are the provider's own, with no markup. Kling 4.0 Flash has 4 routes: "model": "kling_v4_flash" picks one automatically, or pass a route key as "model" to pin it. For the exact price of a request, send the same body to POST https://api.varg.ai/v2/estimate.

fal $0.157/s
fal:fal-ai/kling-video/v4/flash/text-to-video
Text to video Kling 4.0 Flash text to video.
Per second
$0.157/s
Minimum charge
$0.471
Most one request can cost
$3.14
Typical time
~2 min
fal $0.157/s
fal:fal-ai/kling-video/v4/flash/image-to-video
Image to video Kling 4.0 Flash image to video.
Per second
$0.157/s
Minimum charge
$0.471
Most one request can cost
$3.14
Typical time
~2 min
fal $0.157/s
fal:fal-ai/kling-video/v4/flash/reference-to-video
Image to video Kling 4.0 Flash reference to video.
Per second
$0.157/s
Minimum charge
$0.471
Most one request can cost
$3.14
Typical time
~2 min
fal $0.126/s
fal:kling/v4/flash/video-to-video
Video to video Kling 4.0 Flash video editing: edits a 3-20 s source video (@Video1) by text instruction with optional reference images (@Image1..10) and videos (@Video2..5). 720p. Output always keeps the source length and aspect; unified duration and aspect_ratio are ignored.
Per second
$0.126/s
Minimum charge
$0.378
Most one request can cost
$2.53
Typical time
~3 min

Kling 4.0 Flash inputs

The JSON body of the request. Media inputs are URLs: upload a local file with POST /v2/files and pass the URL it returns. Full JSON Schema, no key needed: api.varg.ai/v2/tools/video?model=kling_v4_flash

Kling 4.0 Flash request fields
Field	What it does
`model` string required	`kling_v4_flash` picks a route automatically. To pin one, pass a route key from Pricing above.
`prompt` string	—
`files` array of { url }	—
`aspect_ratio` string	Allowed e.g. 16:9 \| 9:16 \| 1:1 \| 4:3 \| 3:4 \| 21:9 \| auto
`resolution` string	Quality tier. Supported by this model: 720p. Unsupported tiers fall back to the nearest available. Allowed 480p \| 720p \| 1080p \| 4k
`audio` boolean	Native audio track request. Not supported by this model — ignored if sent.
`duration` integer	Length in seconds. Supported by this model's routes: fal: integer 3-20. A non-numeric value such as "auto" is routed to a route whose schema accepts it; when none does, the request is rejected. Allowed 1–120

Provider options

Optional, under provider_options.<provider>. Only the options of the provider that runs the job apply; pin a route to choose it.

`provider_options.fal`

Kling 4.0 Flash options for fal
Field	What it does
`aspect_ratio` string	Allowed 16:9 \| 9:16 \| 1:1 \| 21:9 \| auto
`start_image_url` string (URL)	Image to use as the first frame of the video. Flash does not take an end frame. Max file size: 30.0MB, Min width: 300px, Min height: 300px, Min aspect ratio: 0.40, Max aspect ratio: 2.50, Timeout: 20.0s
`video_url` string (URL)	The video to edit (3-20s), referenced as @Video1. Max file size: 300.0MB, Min width: 700px, Min height: 700px, Max width: 4553px, Max height: 4553px, Min aspect ratio: 0.40, Max aspect ratio: 2.50, Min duration: 3.0s, Max duration: 20.05s, Min FPS: 23.9, Max FPS: 60.05, Timeout: 30.0s

Call the Kling 4.0 Flash API

POST https://api.varg.ai/v2/tools/video/call with Authorization: Bearer $VARG_API_KEY. It answers 202 with a job right away.

1. Send the request

cURL

curl -X POST https://api.varg.ai/v2/tools/video/call \
  -H "Authorization: Bearer $VARG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "kling_v4_flash",
  "prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope.",
  "duration": 5
}'

JavaScript

const headers = {
  Authorization: `Bearer ${process.env.VARG_API_KEY}`,
  'Content-Type': 'application/json',
}

const res = await fetch('https://api.varg.ai/v2/tools/video/call', {
  method: 'POST',
  headers,
  body: JSON.stringify({
    "model": "kling_v4_flash",
    "prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope.",
    "duration": 5
  }),
})
const job = await res.json() // { id: "job_…", status: "queued" }

Python

import os
import requests

headers = {"Authorization": f"Bearer {os.environ['VARG_API_KEY']}"}

job = requests.post(
    "https://api.varg.ai/v2/tools/video/call",
    headers=headers,
    json={
      "model": "kling_v4_flash",
      "prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope.",
      "duration": 5
    },
).json()  # {"id": "job_…", "status": "queued"}

2. Get the result

Poll the job until its status is completed, failed or cancelled; Kling 4.0 Flash typically takes about 2 min. The result is at output.outputs[0].url.

GET /v2/jobs/{id}

curl https://api.varg.ai/v2/jobs/$JOB_ID \
  -H "Authorization: Bearer $VARG_API_KEY"

# Poll until "status" is completed, failed or cancelled.
# The result is in output.outputs[0].url

JavaScript

let current = job
while (!['completed', 'failed', 'cancelled'].includes(current.status)) {
  await new Promise((resolve) => setTimeout(resolve, 3000))
  current = await (await fetch(`https://api.varg.ai/v2/jobs/${current.id}`, { headers })).json()
}
console.log(current.output?.outputs?.[0]?.url)

Python

import time

while job["status"] not in ("completed", "failed", "cancelled"):
    time.sleep(3)
    job = requests.get(f"https://api.varg.ai/v2/jobs/{job['id']}", headers=headers).json()

print(job["output"]["outputs"][0]["url"])

Or take a webhook instead of polling

Add options.webhook_url and varg POSTs the finished job to it.

request body

{
  "model": "kling_v4_flash",
  "prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope.",
  "duration": 5,
  "options": {
    "webhook_url": "https://your-app.com/varg-webhook"
  }
}

From Claude, ChatGPT or Cursor (MCP)

The varg MCP server, https://mcp.varg.ai/mcp, runs Kling 4.0 Flash with call_tool. Sign in with varg, no API key to paste. How to connect it

call_tool

{
  "tool": "video",
  "input": {
    "model": "kling_v4_flash",
    "prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope.",
    "duration": 5
  },
  "wait": true
}