Kling 4.0 API

About Kling 4.0

Up to 30-second 1080p clips with keyframes; may queue when busy.

Call it with the model name kling/4.0/text-to-video on POST /jobs/createTask, from 162 credits for a 5-second clip ($1.62).

Introduction

Kling 4.0 Text to video turns a written brief into a clip of 3 to 30 seconds at 720p or 1080p, in 16:9, 9:16, 1:1 or 21:9 ultrawide. Every clip comes back with a stereo soundtrack generated in the same pass: dialogue you write in quotes, effects and ambience.

Choose a Kling 4.0 mode by starting material

Key features

Up to 30 seconds in one take

Lengths run from 3 to 30 whole seconds, twice the ceiling of Kling 3.0. A long take lets a scene breathe - a slow crane, a full walk across a set - without stitching shorter clips together.

Sound is always on

Each clip carries a two-channel soundtrack. In our tests the dome motor's rumble, wind and a whispered line all came back from the prompt's Sound: line, timed to the picture.

21:9 ultrawide

Besides 16:9, 9:16 and 1:1, Kling 4.0 renders a true 21:9 frame. Our 1080p ultrawide test came back at 2200x940.

Request parameters

Pricing

Prices are in credits, the same credits you use on the website (1 credit = $0.01). The hold is taken when the task is accepted and settled to the actual charge when it finishes; failed tasks are refunded.

For an exact number before you run, send the same body to POST /jobs/quote.

Use cases

Establishing shots with sound

A landscape, a building, a road at dusk - write the place, the light, one camera move and the ambience, and the clip is usable as an opener with its sound already in place.

Short scenes with a spoken line

Put the line in quotes after the action. One clear line per clip is easier for the model to time than overlapping dialogue.

Vertical clips for social

Choose 9:16 and frame the subject in the centre third; the model composes for the vertical frame instead of cropping a wide shot.

Prompt guide & pro tips

Write it in the order it happens

Subject and wardrobe, action, camera move, look, then a separate Sound: line. Our observatory example follows exactly that order.

Draft short, then go long

Generation is slow - a 3-second test took two to four minutes, and requests run one after another rather than in parallel. Find the framing with 3 to 5 seconds at 720p, then render the long or 1080p version.

Describe the sound you want

Because audio is always generated, leaving sound out of the prompt does not give you silence - it gives you whatever the model picks. Name the ambience you want, or say "quiet room tone".

API quick start

Call the Kling 4.0 API in three steps

1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow- and use the same credits as the website.
2. Send the request. POST /jobs/createTask with model kling/4.0/text-to-video and an input object that follows the parameter table. The response returns a task ID straight away.
3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.

# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "kling/4.0/text-to-video",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "aspect_ratio": "16:9",
    "resolution": "720p",
    "duration_seconds": 5
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

Kling 4.0 API questions

All Kling models

• Kling 3.0 API4K clips, multi-shot cuts and motion controlFrom 51 credits for a 5-second clip
• Kling O3 APIKling’s unified model: create, animate, reference and edit up to 4KFrom 51 credits for a 5-second clip
• Kling 4.0 APIUp to 30-second 1080p clips with keyframes; may queue when busyFrom 162 credits for a 5-second clip
• Kling 3.0 Turbo APIFaster Kling 3.0 with sound on every clipFrom 84 credits for a 5-second clip
• Kling 2.6 API1080p clips with optional sound and motion controlFrom 52 credits for a 5-second clip
• Kling 2.5 Turbo API1080p clips with a soundtrack on every takeFrom 42 credits for a 5-second clip
• Kling 2.1 Master APISilent 1080p clips with fine prompt controlFrom 162 credits for a 5-second clip
• Kling 2.1 APIAnimate a frame at 720p or 1080p, with an optional end frameFrom 27 credits for a 5-second clip

Other video APIs

• MiniMax H3 APIExpressive clips with audio, up to 2KFrom 28 credits for a 5-second clip
• Wan 3.0 APIUp to 30-second clips with synced audioFrom 34 credits for a 5-second clip
• MiniMax H3 Max APIFast clips with ambience, effects and musicFrom 38 credits for a 5-second clip
• LTX 2.5 APILong 20-second takes up to 4K with a soundtrackFrom 68 credits for a 5-second clip

More about Kling 4.0

Try it

Kling 4.0 AI Video Generator onlineCreate videos with Kling 4.0 in PopNow

Endpoints

Kling 4.0 · Image to VideoKling 4.0 · Reference to Video

Docs

Kling 4.0 model ID and input schema in the API docsPopNow API quickstart: your first request in five minutesImage to video guide for the PopNow APIWebhooks: get Kling 4.0 results without polling