black-forest-labs/flux-2-flex/editFrom 18 credits per image· Edit Image

FLUX.2 [flex] editing takes one to three source images and an instruction such as new light, a combined scene or added text. It works at 1k and keeps the source shape or offers nine shapes.

Call it with the model name black-forest-labs/flux-2-flex/edit on POST /jobs/createTask, from 18 credits per image ($0.18). New accounts get 30 free credits to try it in the Playground first.

  • Create Image
  • Edit Image
  • Up to 2K
  • Up to 3 reference images
  • 9 aspect ratios
Model nameblack-forest-labs/flux-2-flex/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": "black-forest-labs/flux-2-flex/edit",
  "input": {
    "prompt": "A ceramic teapot on a linen cloth, soft window light, muted palette",
    "image_urls": [
      "https://media.popnow.ai/influencer/examples/marco.webp"
    ],
    "aspect_ratio": "auto",
    "resolution": "1k"
  }
}'

# 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
Standard17.31$0.17

1 credit = $0.01 · Every option and its price: GET /models/black-forest-labs/flux-2-flex/edit

Each task is rounded up to whole credits, so one run at the lowest tier costs 18 credits per image ($0.18).

Limits

Resolutions
1K
Aspect ratios
auto · 1:1 · 16:9 · 9:16 · 4:3 · 3:4 +4
Reference images
3
Prompt length (characters)
5,000
Largest upload
10 MB

Parameters

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

  • promptstringRequired

    Say what to change and what must stay the same.

    Range
    1 – 5000 chars
  • image_urlsarray<string>Required

    Photos to edit or combine. Say in the prompt what each one adds.

    Range
    1 – 3 items · image/jpeg, image/png, image/webp, image/gif · ≤ 10 MB
  • aspect_ratiostringOptional

    The shape of the frame: wide, square or tall.

    Default
    "auto"
    Allowed values
    "auto""1:1""16:9""9:16""4:3""3:4""3:2""2:3""21:9""9:21"
  • resolutionstringOptional

    Output size. Bigger sizes look sharper and cost more.

    Default
    "1k"
    Allowed values
    "1k"
  • seedintegerOptional

    Reuse the same number to get a repeatable result.

    Range
    0 – 2147483647
Raw JSON Schema
{
  "additionalProperties": false,
  "properties": {
    "aspect_ratio": {
      "default": "auto",
      "description": "Output aspect ratio; auto keeps the shape of the first source image.",
      "enum": [
        "auto",
        "1:1",
        "16:9",
        "9:16",
        "4:3",
        "3:4",
        "3:2",
        "2:3",
        "21:9",
        "9:21"
      ],
      "type": "string"
    },
    "image_urls": {
      "description": "One to three source images, in the order your prompt refers to them.",
      "items": {
        "contentMediaType": [
          "image/jpeg",
          "image/png",
          "image/webp",
          "image/gif"
        ],
        "format": "uri",
        "minLength": 1,
        "type": "string"
      },
      "maxItems": 3,
      "minItems": 1,
      "type": "array"
    },
    "prompt": {
      "description": "Say what to change and what must stay the same.",
      "maxLength": 5000,
      "minLength": 1,
      "type": "string"
    },
    "resolution": {
      "default": "1k",
      "description": "Output size tier when you choose an aspect ratio; with auto the result keeps the shape of the first source image.",
      "enum": [
        "1k"
      ],
      "type": "string"
    },
    "seed": {
      "description": "Random seed for controlled comparisons.",
      "maximum": 2147483647,
      "minimum": 0,
      "type": "integer"
    }
  },
  "required": [
    "prompt",
    "image_urls"
  ],
  "type": "object"
}

A real result from FLUX.2 Flex

Coat rain relight
PromptKeep the woman exactly as she is: same face, dark curly hair, rust-orange wool coat, cream turtleneck, dark trousers, and the same pose with her hands in her coat pockets. Change the scene to the same narrow cobblestone street late at night in light rain: the stones are wet and mirror-like, warm #FFB347 light spills from a shop window on the left, a teal neon glow comes from further down the street, and fine raindrops sit on her coat and hair. Moody cinematic night photograph.
The same request through the API
{
  "model": "black-forest-labs/flux-2-flex/edit",
  "input": {
    "prompt": "Keep the woman exactly as she is: same face, dark curly hair, rust-orange wool coat, cream turtleneck, dark trousers, and the same pose with her hands in her coat pockets. Change the scene to the same narrow cobblestone street late at night in light rain: the stones are wet and mirror-like, warm #FFB347 light spills from a shop window on the left, a teal neon glow comes from further down the street, and fine raindrops sit on her coat and hair. Moody cinematic night photograph.",
    "image_urls": [
      "https://media.popnow.ai/influencer/examples/marco.webp"
    ],
    "aspect_ratio": "auto",
    "resolution": "1k",
    "seed": 1201
  }
}

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": "black-forest-labs/flux-2-flex/edit",
  "input": {
    "prompt": "A ceramic teapot on a linen cloth, soft window light, muted palette",
    "image_urls": [
      "https://media.popnow.ai/influencer/examples/marco.webp"
    ],
    "aspect_ratio": "auto",
    "resolution": "1k"
  }
}'

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": "black-forest-labs/flux-2-flex/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.