Face Swap

Quick example

curl https://reapi.ai/api/v1/images/generations \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "face-swap",
    "image_url": "https://example.com/target-photo.jpg",
    "face_image_url": "https://example.com/source-face.jpg"
  }'

import requests

resp = requests.post(
    "https://reapi.ai/api/v1/images/generations",
    headers={
        "Authorization": "Bearer YOUR_API_KEY",
        "Content-Type": "application/json",
    },
    json={
        "model": "face-swap",
        "image_url": "https://example.com/target-photo.jpg",
        "face_image_url": "https://example.com/source-face.jpg",
    },
    timeout=30,
)
print(resp.json())

const r = await fetch("https://reapi.ai/api/v1/images/generations", {
  method: "POST",
  headers: {
    Authorization: "Bearer YOUR_API_KEY",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "face-swap",
    image_url: "https://example.com/target-photo.jpg",
    face_image_url: "https://example.com/source-face.jpg",
  }),
});
console.log(await r.json());

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "io"
    "net/http"
)

func main() {
    body, _ := json.Marshal(map[string]any{
        "model":          "face-swap",
        "image_url":      "https://example.com/target-photo.jpg",
        "face_image_url": "https://example.com/source-face.jpg",
    })
    req, _ := http.NewRequest("POST",
        "https://reapi.ai/api/v1/images/generations", bytes.NewReader(body))
    req.Header.Set("Authorization", "Bearer YOUR_API_KEY")
    req.Header.Set("Content-Type", "application/json")

    resp, _ := http.DefaultClient.Do(req)
    defer resp.Body.Close()
    out, _ := io.ReadAll(resp.Body)
    fmt.Println(string(out))
}

Submit response

{
  "id": "task_018f5a3a1b6e7d9f8c2b4d6e8f0a2c4e",
  "model": "face-swap",
  "status": "processing",
  "created_at": 1735000000
}

Poll GET /api/v1/tasks/{id} (see the Tasks reference) until status === "completed". The completed payload's output.image_urls holds the swapped image URL.

Authentication

Every call needs a Bearer token. Generate keys at reapi.ai/settings/apikeys.

Authorization: Bearer YOUR_API_KEY

Endpoint

POST /api/v1/images/generations
GET  /api/v1/tasks/{id}

Submission is async. The POST returns immediately with a task_id; the task endpoint returns the same envelope until completion. Polling does not consume credits.

Face Swap is image-to-image only — there is no prompt and no size control; the output keeps the target photo's frame. Each request produces exactly one image (no n parameter) and handles one still image (no video).

Request body

model — string, required

Must be face-swap.

image_url — string, required

Public http(s) URL of the target photo: the image whose face will be replaced. Everything else in it — pose, framing, lighting, hair, background — is kept. Base64 and data: URIs are rejected.

face_image_url — string, required

Public http(s) URL of the source face: the face that is placed onto the target. A clear, front-facing shot in even light gives the strongest result. Base64 and data: URIs are rejected.

seed — integer or null, optional

Pin a seed to reproduce a result for the same two images. 0, null, or omitting the field all mean a random seed. No range is enforced beyond it being an integer.

Pricing

Face Swap bills a flat rate per generated image, independent of the input sizes and of seed. Each request produces one image:

credits = ceil(per_image_usd × 1000)

where 1 credit = $0.001 USD. Failed and rejected requests are not charged.

The exact per-image credit cost surfaces on the model page.

Response

The poll envelope returns the image URL in output.image_urls:

{
  "id": "task_019dfd44b7fd74168541552a3260a623",
  "model": "face-swap",
  "status": "completed",
  "output": {
    "image_urls": [
      "https://...png"
    ]
  }
}

Output URLs are valid for 30 days — mirror them to your own storage if you need long-term retention.

Errors

Failures return the standard reAPI envelope { error: { code, message, request_id } }. Common cases:

• Invalid input (a missing or non-http(s) image_url / face_image_url, a non-integer seed, or an unknown field such as content_filter) → 400.
• Insufficient credits → 402.
• Rate limited → 429.
• Upstream could not detect a usable face or failed to generate → the task ends failed and the reserved credits are refunded.

See the full catalog at /docs/api/errors.

Tips

• Source face: front-facing, evenly lit, unobstructed (no sunglasses, no hand over the mouth). The larger and sharper the face, the better the transfer.
• Target photo: the face should be clearly visible and not tiny in the frame. Strong side angles and heavy occlusion weaken the swap.
• What stays: hair, head shape, skin tone of the body, pose and background all come from the target. If you need the whole head replaced, that is a head swap, a different operation.
• Batches: submit many tasks in parallel and poll the ids; pin seed when you want to re-create a specific result later.
• Output URLs expire after 30 days — copy the file into your own storage as part of the same job.

Related

• Z-Image Pro — text-to-image on the same API-key-only terms
• Qwen Image 3 — prompt-driven image editing
• Tasks API
• Error codes