PopNowAPI
Get API key

by Kuaishou

Up to 30-second 1080p clips with keyframes, edits and extensions; may queue when busy

kling/4.0/video-edit
  • Up to 1080p
  • 3–30s clips
  • Sound included
  • Start and end frames
  • Up to 10 reference images
  • 4 aspect ratios
  • Create Video
  • Image to Video
  • Reference to Video
  • Extend Video
  • Edit Video

Call it with the model name kling/4.0/video-edit on POST /jobs/createTask, from $0.564.

Model namekling/4.0/video-edit
EndpointPOST https://api.popnow.ai/api/v1/jobs/createTask
# 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/video-edit",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4",
    "aspect_ratio": "auto",
    "resolution": "720p",
    "duration_seconds": -1
  }
}'

# 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"

The input is built from the schema below, so it passes validation as written. Change the prompt and links to your own.

Price

OptionUSD per second
resolution 720p$0.1128
resolution 1080p$0.1692

Billed in USD · Every option and its price: GET /models/kling/4.0/video-edit

Limits

Clip length
3–30 s
Resolutions
720p · 1080p
Aspect ratios
auto · 16:9 · 9:16 · 1:1 · 21:9
Reference images
10
Largest upload
10 MB
Longest input clip
30 s

Parameters

These fields come from the same schema we check every request against. Fields that are not listed are rejected.

  • promptstringRequired

    Describe the edit: change a subject, the setting, the weather or the style. Refer to the video as @Video1 and to reference images as @Image1, @Image2, numbered in upload order.

    Range
    1 – … chars
  • video_urlstringRequiredChanges the price

    The clip to work on.

    Range
    1 – … chars · video/mp4, video/webm, video/quicktime, video/x-m4v
  • reference_image_urlsarray<string>Optional

    Pictures of the people, outfits or places the result should keep.

    Range
    1 – 10 items · image/jpeg, image/png, image/webp, image/gif · ≤ 10 MB
  • aspect_ratiostringOptional

    The shape of the frame: wide, square or tall.

    Default
    "auto"
    Allowed values
    "auto""16:9""9:16""1:1""21:9"
  • resolutionstringOptionalChanges the price

    Output size. Bigger sizes look sharper and cost more.

    Default
    "720p"
    Allowed values
    "720p""1080p"
  • keep_original_audiobooleanOptional

    Keep the source clip's own sound. Turn it off to generate new synchronized audio instead.

    Default
    true
  • duration_secondsintegerOptionalChanges the price

    How long the clip runs. You pay per second.

    Default
    -1
    Allowed values
    -13456789101112131415161718192021222324252627282930
Raw JSON Schema
{
  "additionalProperties": false,
  "properties": {
    "aspect_ratio": {
      "default": "auto",
      "description": "Output aspect ratio; auto follows the source clip.",
      "enum": [
        "auto",
        "16:9",
        "9:16",
        "1:1",
        "21:9"
      ],
      "type": "string"
    },
    "duration_seconds": {
      "default": -1,
      "description": "Output length in whole seconds, from 3 to 30, or -1 to match the source clip. Billed per second.",
      "enum": [
        -1,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10,
        11,
        12,
        13,
        14,
        15,
        16,
        17,
        18,
        19,
        20,
        21,
        22,
        23,
        24,
        25,
        26,
        27,
        28,
        29,
        30
      ],
      "type": "integer"
    },
    "keep_original_audio": {
      "default": true,
      "description": "Keep the source clip's own sound. Turn it off to generate new synchronized audio instead.",
      "type": "boolean"
    },
    "prompt": {
      "description": "Describe the edit: change a subject, the setting, the weather or the style. Refer to the video as @Video1 and to reference images as @Image1, @Image2, numbered in upload order.",
      "minLength": 1,
      "type": "string"
    },
    "reference_image_urls": {
      "description": "Optional reference images for a subject, object or style to bring into the edit, up to 10. Refer to them as @Image1, @Image2 and so on.",
      "items": {
        "contentMediaType": [
          "image/jpeg",
          "image/png",
          "image/webp",
          "image/gif"
        ],
        "format": "uri",
        "type": "string"
      },
      "maxItems": 10,
      "minItems": 1,
      "type": "array"
    },
    "resolution": {
      "default": "720p",
      "description": "Output resolution. 1080p costs more per second.",
      "enum": [
        "720p",
        "1080p"
      ],
      "type": "string"
    },
    "video_url": {
      "contentMediaType": [
        "video/mp4",
        "video/webm",
        "video/quicktime",
        "video/x-m4v"
      ],
      "format": "uri",
      "minLength": 1,
      "type": "string"
    }
  },
  "required": [
    "prompt",
    "video_url"
  ],
  "type": "object"
}

Responses, polling and callbacks

Every model works the same way: create a task, then poll it or wait for a callback.

Price it first

cURL
curl -X POST https://api.popnow.ai/api/v1/jobs/quote \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "kling/4.0/video-edit",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4",
    "aspect_ratio": "auto",
    "resolution": "720p",
    "duration_seconds": -1
  }
}'

Send the same request body to POST /jobs/quote to see the estimated and maximum USD charge before running. A quote does not run the task or charge your balance.

Accepted

HTTP
HTTP/1.1 202 Accepted

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
    "state": "queued"
  },
  "request_id": "req_example_create"
}

HTTP 202 means accepted: the maximum USD amount is held until settlement. When a task is accepted, we reserve the maximum quoted amount from your API balance. On completion, we charge for actual usage, never more than the hold, and release the remainder. If the task fails, the hold is released.

Check status

cURL
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Poll every few seconds with backoff and stop once state is succeeded, failed, canceled or expired.

Finished task

JSON
{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
    "model": "kling/4.0/video-edit",
    "state": "succeeded",
    "output": {
      "assets": [
        {
          "url": "https://cdn.popnow.ai/tasks/task_01k3m8x9q2z4v7n5p6r8s0t1w3/output.mp4?signature=FROM_RESPONSE",
          "expiresAt": "2026-10-17T12:20:00Z",
          "mime": "video/mp4",
          "width": 1280,
          "height": 720,
          "durationSeconds": 5
        }
      ]
    },
    "settled": true
  },
  "request_id": "req_example_record"
}

Download from url before expiresAt. Need a fresh link later? Ask POST /common/download-url.

Verify a callback

Node.js
import { createHash, createHmac, timingSafeEqual } from "node:crypto";
import express from "express";

const app = express();
// express.raw keeps the exact bytes that were signed; express.json would not match.
app.post("/hooks/popnow", express.raw({ type: "application/json" }), (req, res) => {
  const timestamp = req.header("X-Webhook-Timestamp");
  const signature = req.header("X-Webhook-Signature") ?? "";
  const body = JSON.parse(req.body.toString("utf8"));
  const taskId = body.data?.taskId ?? body.task_id;
  const digest = createHash("sha256").update(req.body).digest("hex");
  const expected = createHmac("sha256", process.env.POPNOW_WEBHOOK_SECRET)
    .update(`${taskId}.${timestamp}.${digest}`)
    .digest("base64");
  const ok = expected.length === signature.length && timingSafeEqual(Buffer.from(expected), Buffer.from(signature));
  // Check the signature first, then reject anything older than five minutes.
  if (!ok || Math.abs(Date.now() / 1000 - Number(timestamp)) > 300) return res.status(401).end();
  res.status(200).end(); // answer fast, then fetch the task and store its files
});

With callBackUrl set, we post the finished task to you. Check the signature against the raw body before you trust it.

Send a local file

cURL
curl -X POST https://api.popnow.ai/api/v1/common/upload-url \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"contentType": "image/png", "bytes": 482113}'

# PUT the file bytes to data.uploadUrl with every header in data.headers, then commit it:
curl -X POST https://api.popnow.ai/api/v1/files/$FILE_ID/commit \
  -H "Authorization: Bearer $POPNOW_API_KEY"
# The commit returns a popnow://f/... reference. Put it in any image, video or
# audio field of the task input instead of a public https URL.

Public https links work as they are. Local files go through upload-url and commit first.