Head Swap API
popnow/head-swap-v1/editFrom 2 credits per imageHead 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 ($0.02). New accounts get 30 free credits to try it in the Playground first.
- Face Swap
popnow/head-swap-v1/editPOST https://api.popnow.ai/api/v1/jobs/createTask# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(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: $IDEMPOTENCY_KEY" \
-d '{
"model": "popnow/head-swap-v1/edit",
"input": {
"image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
"reference_image_url": "https://media.popnow.ai/influencer/examples/ava.webp"
}
}'
# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
-H "Authorization: Bearer $POPNOW_API_KEY"// 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} ${body.msg}`);
return body.data;
}
const { taskId } = await call("/jobs/createTask", {
method: "POST",
headers: { "Content-Type": "application/json", "Idempotency-Key": crypto.randomUUID() },
body: JSON.stringify({
"model": "popnow/head-swap-v1/edit",
"input": {
"image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
"reference_image_url": "https://media.popnow.ai/influencer/examples/ava.webp"
}
}),
});
// Poll with backoff. A finished task may still be copying files: wait while an asset is pending.
let task;
for (let delay = 2000; ; delay = Math.min(delay * 1.5, 15000)) {
await sleep(delay);
task = await call(`/jobs/recordInfo?taskId=${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": "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"
}
},
)["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 | Credits per image | ≈ USD |
|---|---|---|
| Standard | 1.95 | $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_urlstringRequiredThe picture to start from.
reference_image_urlstringRequiredReference head image. The whole head, including hair and head shape, is transferred onto the target.
seedintegerOptionalReuse the same number to get a repeatable result.
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

{
"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 -X POST https://api.popnow.ai/api/v1/jobs/quote \
-H "Authorization: Bearer $POPNOW_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "popnow/head-swap-v1/edit",
"input": {
"image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
"reference_image_url": "https://media.popnow.ai/influencer/examples/ava.webp"
}
}'Same body as createTask. It returns the expected and the highest possible charge, and runs nothing.
Accepted
HTTP/1.1 202 Accepted
{
"code": 200,
"msg": "success",
"data": {
"taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
"state": "queued"
},
"request_id": "req_example_create"
}HTTP 202 means the task was accepted and the credits are held, not charged yet. The final charge never goes above the hold.
Check status
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
-H "Authorization: Bearer $POPNOW_API_KEY"Poll every few seconds with backoff and stop once state is succeeded, failed, canceled or expired.
Finished task
{
"code": 200,
"msg": "success",
"data": {
"taskId": "task_01k3m8x9q2z4v7n5p6r8s0t1w3",
"model": "popnow/head-swap-v1/edit",
"state": "succeeded",
"output": {
"assets": [
{
"url": "https://cdn.popnow.ai/tasks/task_01k3m8x9q2z4v7n5p6r8s0t1w3/output.png?signature=FROM_RESPONSE",
"expiresAt": "2026-10-17T12:20:00Z",
"mime": "image/png",
"width": 1024,
"height": 1024
}
]
},
"settled": true
},
"request_id": "req_example_record"
}Download from url before expiresAt. Need a fresh link later? Ask POST /common/download-url.
Verify a callback
import { createHash, createHmac, timingSafeEqual } from "node:crypto";
import express from "express";
const app = express();
// express.raw keeps the exact bytes that were signed; express.json would not match.
app.post("/hooks/popnow", express.raw({ type: "application/json" }), (req, res) => {
const timestamp = req.header("X-Webhook-Timestamp");
const signature = req.header("X-Webhook-Signature") ?? "";
const body = JSON.parse(req.body.toString("utf8"));
const taskId = body.data?.taskId ?? body.task_id;
const digest = createHash("sha256").update(req.body).digest("hex");
const expected = createHmac("sha256", process.env.POPNOW_WEBHOOK_SECRET)
.update(`${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.

