Head Swap API

popnow/head-swap-v1/editFrom 2 credits per image

Head Swap transfers an entire head from a reference photo onto the person in a target image, hair and head shape included, keeping the target's body, wardrobe, pose and background. Two URLs and an optional seed.

Call it with the model name popnow/head-swap-v1/edit on POST /jobs/createTask, from 2 credits per image ($0.02). New accounts get 30 free credits to try it in the Playground first.

  • Face Swap
Model namepopnow/head-swap-v1/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": "popnow/head-swap-v1/edit",
  "input": {
    "image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
    "reference_image_url": "https://media.popnow.ai/influencer/examples/ava.webp"
  }
}'

# 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

OptionCredits per image≈ USD
Standard1.95$0.02

1 credit = $0.01 · Every option and its price: GET /models/popnow/head-swap-v1/edit

Each task is rounded up to whole credits, so one run at the lowest tier costs 2 credits per image ($0.02).

Parameters

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

  • image_urlstringRequired

    The picture to start from.

    Range
    1 – … chars · image/jpeg, image/png, image/webp, image/gif
  • reference_image_urlstringRequired

    Reference head image. The whole head, including hair and head shape, is transferred onto the target.

    Range
    1 – … chars · image/jpeg, image/png, image/webp, image/gif
  • seedintegerOptional

    Reuse the same number to get a repeatable result.

    Range
    0 – 2147483647
Raw JSON Schema
{
  "additionalProperties": false,
  "properties": {
    "image_url": {
      "contentMediaType": [
        "image/jpeg",
        "image/png",
        "image/webp",
        "image/gif"
      ],
      "description": "Target image. The head of the person in this image is the one that gets replaced.",
      "minLength": 1,
      "type": "string"
    },
    "reference_image_url": {
      "contentMediaType": [
        "image/jpeg",
        "image/png",
        "image/webp",
        "image/gif"
      ],
      "description": "Reference head image. The whole head, including hair and head shape, is transferred onto the target.",
      "minLength": 1,
      "type": "string"
    },
    "seed": {
      "description": "Random seed; zero requests a random seed.",
      "maximum": 2147483647,
      "minimum": 0,
      "type": "integer"
    }
  },
  "required": [
    "image_url",
    "reference_image_url"
  ],
  "type": "object"
}

A real result from Head Swap

Stage relight recast
The same request through the API
{
  "model": "popnow/head-swap-v1/edit",
  "input": {
    "image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
    "reference_image_url": "https://media.popnow.ai/influencer/examples/ava.webp",
    "seed": 20260907
  }
}

This one started from an uploaded file: put your own link where the example link is.

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": "popnow/head-swap-v1/edit",
  "input": {
    "image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
    "reference_image_url": "https://media.popnow.ai/influencer/examples/ava.webp"
  }
}'

Same body as createTask. It returns the expected and the highest possible charge, and runs nothing.

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 the task was accepted and the credits are held, not charged yet. The final charge never goes above the hold.

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": "popnow/head-swap-v1/edit",
    "state": "succeeded",
    "output": {
      "assets": [
        {
          "url": "https://cdn.popnow.ai/tasks/task_01k3m8x9q2z4v7n5p6r8s0t1w3/output.png?signature=FROM_RESPONSE",
          "expiresAt": "2026-10-17T12:20:00Z",
          "mime": "image/png",
          "width": 1024,
          "height": 1024
        }
      ]
    },
    "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.