PopNowAPI
Get API key

LTX 2.3 Plus API

by Lightricks

LTX 2.3 image-to-video, 3 to 20 seconds up to 1080p

lightricks/ltx-2.3-plus/video-extend
  • Up to 1080p
  • 3–20s clips
  • Image to Video
  • Extend Video

Call it with the model name lightricks/ltx-2.3-plus/video-extend on POST /jobs/createTask, from $0.095.

Model namelightricks/ltx-2.3-plus/video-extend
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": "lightricks/ltx-2.3-plus/video-extend",
  "input": {
    "preset": "tuned",
    "duration_seconds": 5,
    "resolution": "480p",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4"
  }
}'

# 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 480p$0.019
resolution 720p$0.038
resolution 1080p$0.057

Billed in USD · Every option and its price: GET /models/lightricks/ltx-2.3-plus/video-extend

Limits

Clip length
3–20 s
Resolutions
480p · 720p · 1080p
Longest input clip
60 s

Parameters

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

  • video_urlstringRequired

    The clip to work on.

    Range
    1 – … chars · video/mp4, video/webm, video/quicktime, video/x-m4v
  • presetstringOptional

    Style preset bundle. tuned is the recommended general-purpose stack; original applies light styling only.

    Default
    "tuned"
    Allowed values
    "tuned""original"
  • promptstringOptional

    Describe what happens next: the action that follows and the camera move. You can leave it empty.

  • duration_secondsintegerOptionalChanges the price

    How long the clip runs. You pay per second.

    Default
    5
    Range
    3 – 20
  • resolutionstringOptionalChanges the price

    Output size. Bigger sizes look sharper and cost more.

    Default
    "480p"
    Allowed values
    "480p""720p""1080p"
  • seedintegerOptional

    Reuse the same number to get a repeatable result.

    Range
    0 – 2147483647
Raw JSON Schema
{
  "additionalProperties": false,
  "properties": {
    "duration_seconds": {
      "default": 5,
      "description": "Length of the new segment in whole seconds, from 3 to 20. The source clip is added on top and is not billed.",
      "maximum": 20,
      "minimum": 3,
      "type": "integer"
    },
    "preset": {
      "default": "tuned",
      "description": "Style preset bundle. tuned is the recommended general-purpose stack; original applies light styling only.",
      "enum": [
        "tuned",
        "original"
      ],
      "type": "string"
    },
    "prompt": {
      "description": "Describe what happens next: the action that follows and the camera move. You can leave it empty.",
      "type": "string"
    },
    "resolution": {
      "default": "480p",
      "description": "Resolution of the new segment. It sets how sharp the new part is generated; match your source clip.",
      "enum": [
        "480p",
        "720p",
        "1080p"
      ],
      "type": "string"
    },
    "seed": {
      "description": "Random seed. Keep it fixed only for controlled comparisons, not as a frame-identical guarantee.",
      "maximum": 2147483647,
      "minimum": 0,
      "type": "integer"
    },
    "video_url": {
      "contentMediaType": [
        "video/mp4",
        "video/webm",
        "video/quicktime",
        "video/x-m4v"
      ],
      "format": "uri",
      "minLength": 1,
      "type": "string"
    }
  },
  "required": [
    "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": "lightricks/ltx-2.3-plus/video-extend",
  "input": {
    "preset": "tuned",
    "duration_seconds": 5,
    "resolution": "480p",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4"
  }
}'

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": "lightricks/ltx-2.3-plus/video-extend",
    "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.

About LTX 2.3 Plus

LTX 2.3 image-to-video, 3 to 20 seconds up to 1080p.

Call it with the model name lightricks/ltx-2.3-plus/video-extend on POST /jobs/createTask, from $0.095.

Request parameters

ParameterRequiredDescription
duration_secondsNoHow long the clip runs. You pay per second. ≥ 3 · ≤ 20 · Default: 5
presetNoStyle preset bundle. tuned is the recommended general-purpose stack; original applies light styling only. tuned · original · Default: tuned
promptNoDescribe what happens next: the action that follows and the camera move. You can leave it empty.
resolutionNoOutput size. Bigger sizes look sharper and cost more. 480p · 720p · 1080p · Default: 480p
seedNoReuse the same number to get a repeatable result. ≥ 0 · ≤ 2147483647
video_urlYesThe clip to work on.

Pricing

Prices are in USD. The API uses a separate USD balance. Website credits cannot be used or transferred to it, and API funds cannot be transferred to website credits. 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.

OptionUSD per second
resolution 480p$0.019
resolution 720p$0.038
resolution 1080p$0.057

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.

API quick start

Call the LTX 2.3 Plus 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-. API calls use your separate USD balance.
  2. Send the request. POST /jobs/createTask with model lightricks/ltx-2.3-plus/video-extend 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": "lightricks/ltx-2.3-plus/video-extend",
  "input": {
    "preset": "tuned",
    "duration_seconds": 5,
    "resolution": "480p",
    "video_url": "https://media.popnow.ai/effects/flower-bloom-1abd6efb.mp4"
  }
}'

# 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.

LTX 2.3 Plus API questions

How much does the LTX 2.3 Plus API cost?

LTX 2.3 Plus starts at $0.095 for a 5-second clip with Extend Video, its cheapest task. Prices by option: 480p $0.019 per second, 720p $0.038 per second, 1080p $0.057 per second. The API uses a separate USD balance. Website credits cannot be used or transferred to it, and API funds cannot be transferred to website credits. 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.

What are the limits of the LTX 2.3 Plus · Extend Video API?

Clip length: 3–20 s; Resolutions: 480p · 720p · 1080p; Longest input clip: 60 s. Requests outside these limits are rejected before anything is charged.

More about LTX 2.3 Plus