Up to 30-second 1080p clips with keyframes, edits and extensions; may queue when busy
- 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 $0.564.
kling/4.0/video-editPOST https://api.popnow.ai/api/v1/jobs/createTask# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(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"// Node 18+ (or any runtime with fetch). Keep the API key on your server.
const BASE = "https://api.popnow.ai/api/v1";
const headers = { Authorization: `Bearer ${process.env.POPNOW_API_KEY}` };
const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
async function call(path, init = {}) {
const res = await fetch(BASE + path, { ...init, headers: { ...headers, ...init.headers } });
const body = await res.json();
if (body.code !== 200) throw new Error(`${body.code} ${body.msg}`);
return body.data;
}
const { taskId } = await call("/jobs/createTask", {
method: "POST",
headers: { "Content-Type": "application/json", "Idempotency-Key": crypto.randomUUID() },
body: JSON.stringify({
"model": "kling/4.0/video-edit",
"input": {
"prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
"video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4",
"aspect_ratio": "auto",
"resolution": "720p",
"duration_seconds": -1
}
}),
});
// Poll with backoff. A finished task may still be copying files: wait while an asset is pending.
let task;
for (let delay = 2000; ; delay = Math.min(delay * 1.5, 15000)) {
await sleep(delay);
task = await call(`/jobs/recordInfo?taskId=${taskId}`);
const copying = (task.output?.assets ?? []).some((a) => a.pending && !a.unavailable);
if (["succeeded", "failed", "canceled", "expired"].includes(task.state) && !copying) break;
}
if (task.state !== "succeeded") throw new Error(`${task.state}: ${task.errorMessage ?? "no detail"}`);
// Each asset has a signed url (no API key needed) that expires at expiresAt: save the file.
for (const asset of task.output.assets) console.log(asset.url);import os, time, uuid, requests
BASE = "https://api.popnow.ai/api/v1"
HEADERS = {"Authorization": f"Bearer {os.environ['POPNOW_API_KEY']}"}
def call(method, path, **kwargs):
body = requests.request(method, BASE + path, headers={**HEADERS, **kwargs.pop("headers", {})}, timeout=30, **kwargs).json()
if body["code"] != 200:
raise RuntimeError(f'{body["code"]} {body["msg"]}')
return body["data"]
task_id = call(
"POST",
"/jobs/createTask",
headers={"Idempotency-Key": str(uuid.uuid4())}, # reuse it if you retry
json={
"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
}
},
)["taskId"]
# Poll with backoff. A finished task may still be copying files: wait while an asset is pending.
delay = 2.0
while True:
time.sleep(delay)
task = call("GET", "/jobs/recordInfo", params={"taskId": task_id})
assets = (task.get("output") or {}).get("assets") or []
copying = any(a.get("pending") and not a.get("unavailable") for a in assets)
if task["state"] in ("succeeded", "failed", "canceled", "expired") and not copying:
break
delay = min(delay * 1.5, 15.0)
if task["state"] != "succeeded":
raise RuntimeError(f'{task["state"]}: {task.get("errorMessage", "no detail")}')
# Each asset has a signed url (no API key needed) that expires at expiresAt: save the file.
for asset in assets:
print(asset["url"])The input is built from the schema below, so it passes validation as written. Change the prompt and links to your own.
Price
| Option | USD 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.
promptstringRequiredDescribe 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.
video_urlstringRequiredChanges the priceThe clip to work on.
reference_image_urlsarray<string>OptionalPictures of the people, outfits or places the result should keep.
aspect_ratiostringOptionalThe shape of the frame: wide, square or tall.
resolutionstringOptionalChanges the priceOutput size. Bigger sizes look sharper and cost more.
keep_original_audiobooleanOptionalKeep the source clip's own sound. Turn it off to generate new synchronized audio instead.
duration_secondsintegerOptionalChanges the priceHow long the clip runs. You pay per second.
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 -X POST https://api.popnow.ai/api/v1/jobs/quote \
-H "Authorization: Bearer $POPNOW_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "kling/4.0/video-edit",
"input": {
"prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
"video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4",
"aspect_ratio": "auto",
"resolution": "720p",
"duration_seconds": -1
}
}'Send the same request body to POST /jobs/quote to see the estimated and maximum USD charge before running. A quote does not run the task or charge your balance.
Accepted
HTTP/1.1 202 Accepted
{
"code": 200,
"msg": "success",
"data": {
"taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
"state": "queued"
},
"request_id": "req_example_create"
}HTTP 202 means accepted: the maximum USD amount is held until settlement. When a task is accepted, we reserve the maximum quoted amount from your API balance. On completion, we charge for actual usage, never more than the hold, and release the remainder. If the task fails, the hold is released.
Check status
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
-H "Authorization: Bearer $POPNOW_API_KEY"Poll every few seconds with backoff and stop once state is succeeded, failed, canceled or expired.
Finished task
{
"code": 200,
"msg": "success",
"data": {
"taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
"model": "kling/4.0/video-edit",
"state": "succeeded",
"output": {
"assets": [
{
"url": "https://cdn.popnow.ai/tasks/task_01k3m8x9q2z4v7n5p6r8s0t1w3/output.mp4?signature=FROM_RESPONSE",
"expiresAt": "2026-10-17T12:20:00Z",
"mime": "video/mp4",
"width": 1280,
"height": 720,
"durationSeconds": 5
}
]
},
"settled": true
},
"request_id": "req_example_record"
}Download from url before expiresAt. Need a fresh link later? Ask POST /common/download-url.
Verify a callback
import { createHash, createHmac, timingSafeEqual } from "node:crypto";
import express from "express";
const app = express();
// express.raw keeps the exact bytes that were signed; express.json would not match.
app.post("/hooks/popnow", express.raw({ type: "application/json" }), (req, res) => {
const timestamp = req.header("X-Webhook-Timestamp");
const signature = req.header("X-Webhook-Signature") ?? "";
const body = JSON.parse(req.body.toString("utf8"));
const taskId = body.data?.taskId ?? body.task_id;
const digest = createHash("sha256").update(req.body).digest("hex");
const expected = createHmac("sha256", process.env.POPNOW_WEBHOOK_SECRET)
.update(`${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 -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.