FLUX Kontext

FLUX.1 Kontext [pro] handles both text and reference images as inputs, seamlessly enabling targeted, local edits and complex transformations of entire scenes.

Pricing: $0.04/image. Endpoint: POST /v1/models/black-forest-labs/flux-pro/kontext/runs.

FLUX.1 Kontext [pro] handles both text and reference images as inputs, seamlessly enabling targeted, local edits and complex transformations of entire scenes.

Overview

• Endpoint: https://api.runflow.io/v1/models/black-forest-labs/flux-pro/kontext/runs
• Model ID: black-forest-labs/flux-pro/kontext
• Provider: Black Forest Labs
• License: commercial
• Last Updated: 2026-04-06

Pricing

• Base price: $0.04/image
• Note: ~25 runs per $1

FLUX Kontext API

Endpoint: POST /v1/models/black-forest-labs/flux-pro/kontext/runs

Run the model

Python

import requests

response = requests.post(
    "https://api.runflow.io/v1/models/black-forest-labs/flux-pro/kontext/runs",
    headers={"Authorization": "Bearer RUNFLOW_API_KEY"},
    json={
        "input": {
            "prompt": "Add a fluffy orange tabby cat sleeping on the desk between the two monitors, curled up on a small cushion, one paw draped over the keyboard. The cat is illuminated by the monitor glow. Everything else stays exactly the same.",
            "image_url": "https://public.runflow.io/images/models/_shared/base-engineer.png"
        },
        "callback_url": "https://your-server.com/webhook"
    },
)

data = response.json()
print(data)

Node.js

const response = await fetch(
  "https://api.runflow.io/v1/models/black-forest-labs/flux-pro/kontext/runs",
  {
    method: "POST",
    headers: {
      "Authorization": "Bearer RUNFLOW_API_KEY",
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
        "input": {
            "prompt": "Add a fluffy orange tabby cat sleeping on the desk between the two monitors, curled up on a small cushion, one paw draped over the keyboard. The cat is illuminated by the monitor glow. Everything else stays exactly the same.",
            "image_url": "https://public.runflow.io/images/models/_shared/base-engineer.png"
        },
        "callback_url": "https://your-server.com/webhook"
    }),
  }
);

const data = await response.json();
console.log(data);

cURL

curl -X POST https://api.runflow.io/v1/models/black-forest-labs/flux-pro/kontext/runs \
  -H "Authorization: Bearer $RUNFLOW_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'JSON'
{
    "input": {
        "prompt": "Add a fluffy orange tabby cat sleeping on the desk between the two monitors, curled up on a small cushion, one paw draped over the keyboard. The cat is illuminated by the monitor glow. Everything else stays exactly the same.",
        "image_url": "https://public.runflow.io/images/models/_shared/base-engineer.png"
    },
    "callback_url": "https://your-server.com/webhook"
}
JSON

Request parameters

Parameter	Type	Required	Description
input	object	required	Model input parameters. See “Input schema” below.
callback_url	string | null	optional	Webhook URL - POSTed when the run reaches a terminal state.
metadata	object | null	optional	Arbitrary key-value pairs attached to the run.

Input schema

Field	Type	Required	Allowed values	Description
prompt	string	required	Any	Editing instruction describing the desired transformation.
image_url	image	required	Any	URL of the source image to edit.
aspect_ratio	string	optional	21:9, 16:9, 4:3, 3:2, 1:1, 2:3, 3:4, 9:16, 9:21	Output aspect ratio. Options: square_hd, square, portrait_4_3, portrait_16_9, landscape_4_3, landscape_16_9.
num_images	integer	optional	Any	Number of images to generate per request. Range: 1–4. Default: 1.
guidance_scale	float	optional	Any	How closely the model follows the prompt. Range: 1–20. Default: 3.5.
output_format	string	optional	jpeg, png	Output format. Options: “jpeg”, “png”. Default: “jpeg”.
safety_tolerance	string	optional	Any	Content moderation strictness. 1 = most strict, 6 = most permissive. Default: 2.
enhance_prompt	boolean	optional	Any	Automatically enhance the prompt for better results. Default: false.
seed	integer	optional	Any	Random seed for reproducible outputs.
sync_mode	boolean	optional	Any	Return media as data URI without storing in request history. Default: false.

Output schema

Field	Type	Description
outputs	json	Unified output array - one entry per generated artifact with url/type/width/height/duration/etc.
seed	json	Seed of the generated Image. It will be the same value of the one passed in the input or the randomly generated that was used in case none was passed.
model_data	json	Model-specific extra fields (prompt, description, actual_prompt, masks, etc.) keyed by field name.
nsfw_detected	json	true if the provider flagged output as NSFW, false if cleared, null if not checked.
timing	json	Provider timing info (inference_ms etc.), or null.

Callback payload

When you provide a callback_url, Runflow POSTs to it once the run reaches a terminal state.

Field	Type	Description
event	string	Event type: “run.completed”, “run.failed”, or “run.cancelled”.
run_id	string	The unique identifier of the run.
status	string	Terminal status: “succeeded”, “failed”, or “cancelled”.
output	object | null	The run output. Null if the run failed or was cancelled.
duration_ms	number | null	Total run duration in milliseconds.
created_at	string | null	ISO 8601 timestamp when the run was created.
completed_at	string | null	ISO 8601 timestamp when the run reached terminal state.
metadata	object | null	The metadata object passed at run creation, if any.

• Retries: 3 attempts with exponential backoff (1s, 2s). Retries on 5xx / network errors only.
• Headers: Runflow-Request-Id is always sent. Runflow-Signature is sent if a signing secret is configured.

Additional Resources

• Playground
• API Reference
• Documentation
• OpenAPI

Related

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Run lifecycle

Callbacks, polling, statuses.

Callbacks

Handle async results.

Pricing

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