Use Flux.1 Kontext with Comfy Router

API Reference for Flux.1 Kontext. Flux.1 Kontext is Black Forest Labs’ instruction-driven image editing model: send an image and a text instruction, get the edited image back with the rest of the scene preserved.

Comfy Router is not generally available yet. POST /v2/models/{provider}/{model} and its catalog and schema siblings are not serving requests yet: an authenticated call answers 404 today. The snippets on this page document the contract those routes will serve, published ahead of the rollout so your integration is ready to write against.

Quick start

Create a key at platform.comfy.org/profile/api-keys and export it as COMFY_API_KEY. The Python and TypeScript snippets use the Comfy SDKs (pip install comfy-sdk, npm install @comfyorg/sdk); the cURL snippet is the same call over raw HTTP. Pick the model you want to call. Everything below, from the snippets to the schema and examples, follows your choice.

Kontext Pro
Kontext Max

Model ID: bfl/flux-kontext-proEndpoint: POST https://api.comfy.org/v2/models/bfl/flux-kontext-pro

import base64

from comfy_sdk import Comfy

with open("input.jpg", "rb") as f:
    input_image = base64.b64encode(f.read()).decode()

# Reads COMFY_API_KEY from the environment. Each call sends a fresh
# Idempotency-Key and waits up to 10 minutes for the finished result.
with Comfy() as client:
    result = client.models.run(
        "bfl/flux-kontext-pro",
        {
            "prompt": "replace the background with a sunlit beach, keep the subject unchanged",
            "input_image": input_image,
            "aspect_ratio": "1:1",
        },
    )

print("image:", result["result"]["sample"])

import { comfy } from "@comfyorg/sdk";
import { readFile } from "node:fs/promises";

const inputImage = (await readFile("input.jpg")).toString("base64");

// Reads COMFY_API_KEY from the environment. Each call sends a fresh
// Idempotency-Key and waits up to 10 minutes for the finished result.
type Result = { result: { sample: string } };
const { data } = await comfy.models.run<Result>("bfl/flux-kontext-pro", {
  prompt: "replace the background with a sunlit beach, keep the subject unchanged",
  input_image: inputImage,
  aspect_ratio: "1:1",
});

console.log("image:", data.result.sample);

INPUT_IMAGE=$(base64 < input.jpg | tr -d '\n')

curl https://api.comfy.org/v2/models/bfl/flux-kontext-pro \
  -H "X-API-Key: $COMFY_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d "{\"prompt\": \"replace the background with a sunlit beach, keep the subject unchanged\", \"input_image\": \"$INPUT_IMAGE\", \"aspect_ratio\": \"1:1\"}"

Schema

Input

string

Aspect ratio of the output between 21:9 and 9:21, e.g. 16:9. Defaults to the input image’s aspect ratio when one is given, otherwise 1:1.

string

Image to edit, as a base64-encoded image or an http(s) URL. Optional; without it the model generates from the prompt alone.

string

Additional reference image, base64-encoded or an http(s) URL (experimental multi-reference).

string

Additional reference image, base64-encoded or an http(s) URL (experimental multi-reference).

string

Additional reference image, base64-encoded or an http(s) URL (experimental multi-reference).

string

default:"\"png\""

Output image format.Possible values: jpeg, png, webp

string

required

Text prompt describing the edit to apply to input_image, or the image to generate when no input_image is given.

boolean

default:"false"

Whether to upsample the prompt. If active, the prompt is automatically modified for more creative generation.

integer

default:"2"

Tolerance level for input and output moderation, between 0 (most strict) and 6 (least strict).Range: 0 to 6

integer

Optional seed for reproducibility. A random seed is used when omitted.

string

Optional secret for webhook signature verification.

string (uri)

URL to receive webhook notifications.Format: uri

Generated from the schema Router serves at GET /v2/models/bfl/flux-kontext-pro/openapi.json, the same document it validates a call against before the request reaches the provider.

Output

number

Provider-reported cost in credits, populated once the task is Ready.Format: float

string

required

BFL task identifier.

number

Optional generation progress reported by BFL.Range: 0 to 1Format: float

object

required

The finished generation. Not nullable here: this component’s required entry is a promise that a 200 carries the result, and a nullable result would reduce it to a key-presence check.

number

Provider-reported cost of the generation. This is BFL’s number, not the Comfy charge.Format: double

number

Provider-reported generation duration in seconds.Format: double

number

Provider-reported completion time of the generation, in seconds since the Unix epoch. double for the same reason as start_time.Format: double

string

The prompt the generation actually ran, after any prompt upsampling.

string (uri)

Signed URL for the generated asset. Router re-hosts the asset onto Comfy storage and rewrites this field, so it is normally a Comfy-hosted URL valid for up to 24 hours - signed for 24 hours when minted, and replayed from a 23-hour memo, so a later poll can hand back one with as little as an hour left; a leaf whose re-host could not be performed keeps BFL’s own short-lived delivery URL instead - roughly two hours for video, roughly ten minutes for images. Either way the link expires, so download the asset rather than storing the URL.Format: uri

integer

The seed the generation used, whether supplied or chosen by the provider. Declared int64 because BFL returns seeds above 2^31 (e.g. 2784347701), which an unformatted integer generates as a 32-bit field in many SDK generators.Format: int64

number

Provider-reported start time of the generation, in seconds since the Unix epoch. double, not float: float32 spacing near a present-day epoch value is ~128 seconds, which collapses a whole generation’s span to a single decoded value.Format: double

string

required

Task status: Pending, Reasoning, Generating, Ready, Request Moderated, Content Moderated, Error, or Task not found.

Examples

Input

{
  "prompt": "A watercolor painting of a lighthouse at dawn, soft light on the water"
}

Output

{
  "cost": null,
  "id": "b2e0c1a4-0f2f-4a55-9f2e-2f9a1c0d4e77",
  "progress": null,
  "result": {
    "cost": null,
    "duration": 3.4,
    "end_time": 1767225603.4,
    "prompt": "A watercolor painting of a lighthouse at dawn, soft light on the water",
    "sample": "https://example.invalid/bfl/flux-pro-1.1/sample.png",
    "seed": 2784347701,
    "start_time": 1767225600
  },
  "status": "Ready"
}

The URL is temporary. Download the image promptly if you need to keep it.

Model ID: bfl/flux-kontext-maxEndpoint: POST https://api.comfy.org/v2/models/bfl/flux-kontext-max

import base64

from comfy_sdk import Comfy

with open("input.jpg", "rb") as f:
    input_image = base64.b64encode(f.read()).decode()

# Reads COMFY_API_KEY from the environment. Each call sends a fresh
# Idempotency-Key and waits up to 10 minutes for the finished result.
with Comfy() as client:
    result = client.models.run(
        "bfl/flux-kontext-max",
        {
            "prompt": "replace the background with a sunlit beach, keep the subject unchanged",
            "input_image": input_image,
            "aspect_ratio": "1:1",
        },
    )

print("image:", result["result"]["sample"])

import { comfy } from "@comfyorg/sdk";
import { readFile } from "node:fs/promises";

const inputImage = (await readFile("input.jpg")).toString("base64");

// Reads COMFY_API_KEY from the environment. Each call sends a fresh
// Idempotency-Key and waits up to 10 minutes for the finished result.
type Result = { result: { sample: string } };
const { data } = await comfy.models.run<Result>("bfl/flux-kontext-max", {
  prompt: "replace the background with a sunlit beach, keep the subject unchanged",
  input_image: inputImage,
  aspect_ratio: "1:1",
});

console.log("image:", data.result.sample);

INPUT_IMAGE=$(base64 < input.jpg | tr -d '\n')

curl https://api.comfy.org/v2/models/bfl/flux-kontext-max \
  -H "X-API-Key: $COMFY_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d "{\"prompt\": \"replace the background with a sunlit beach, keep the subject unchanged\", \"input_image\": \"$INPUT_IMAGE\", \"aspect_ratio\": \"1:1\"}"

Schema

Input

string

Aspect ratio of the output between 21:9 and 9:21, e.g. 16:9. Defaults to the input image’s aspect ratio when one is given, otherwise 1:1.

string

Image to edit, as a base64-encoded image or an http(s) URL. Optional; without it the model generates from the prompt alone.

string

Additional reference image, base64-encoded or an http(s) URL (experimental multi-reference).

string

Additional reference image, base64-encoded or an http(s) URL (experimental multi-reference).

string

Additional reference image, base64-encoded or an http(s) URL (experimental multi-reference).

string

default:"\"png\""

Output image format.Possible values: jpeg, png, webp

string

required

Text prompt describing the edit to apply to input_image, or the image to generate when no input_image is given.

boolean

default:"false"

Whether to upsample the prompt. If active, the prompt is automatically modified for more creative generation.

integer

default:"2"

Tolerance level for input and output moderation, between 0 (most strict) and 6 (least strict).Range: 0 to 6

integer

Optional seed for reproducibility. A random seed is used when omitted.

string

Optional secret for webhook signature verification.

string (uri)

URL to receive webhook notifications.Format: uri

Generated from the schema Router serves at GET /v2/models/bfl/flux-kontext-max/openapi.json, the same document it validates a call against before the request reaches the provider.

Output

number

Provider-reported cost in credits, populated once the task is Ready.Format: float

string

required

BFL task identifier.

number

Optional generation progress reported by BFL.Range: 0 to 1Format: float

object

required

The finished generation. Not nullable here: this component’s required entry is a promise that a 200 carries the result, and a nullable result would reduce it to a key-presence check.

number

Provider-reported cost of the generation. This is BFL’s number, not the Comfy charge.Format: double

number

Provider-reported generation duration in seconds.Format: double

number

Provider-reported completion time of the generation, in seconds since the Unix epoch. double for the same reason as start_time.Format: double

string

The prompt the generation actually ran, after any prompt upsampling.

string (uri)

integer

number

string

required

Task status: Pending, Reasoning, Generating, Ready, Request Moderated, Content Moderated, Error, or Task not found.

Examples

Input

{
  "prompt": "A watercolor painting of a lighthouse at dawn, soft light on the water"
}

Output

{
  "cost": null,
  "id": "b2e0c1a4-0f2f-4a55-9f2e-2f9a1c0d4e77",
  "progress": null,
  "result": {
    "cost": null,
    "duration": 3.4,
    "end_time": 1767225603.4,
    "prompt": "A watercolor painting of a lighthouse at dawn, soft light on the water",
    "sample": "https://example.invalid/bfl/flux-pro-1.1/sample.png",
    "seed": 2784347701,
    "start_time": 1767225600
  },
  "status": "Ready"
}

The URL is temporary. Download the image promptly if you need to keep it.

Before you ship

The snippets above are the shortest working call. Three things are the same for every model and are documented once on the Comfy Router headers page: send an Idempotency-Key on every paid call and reuse it when you retry, expect the connection to be held up to Router’s 10 minute deadline, and keep X-Comfy-Request-Id from every response. The SDKs do all three for you; the cURL tab does none of them. On failure, X-Comfy-Error-Type names the bucket, and a 422 means the body failed the model’s schema and was never billed.

Headers

Authentication, idempotency, request IDs, error buckets, retry pacing, spend limits.

Quick Start

Typed error handling in Python and TypeScript, reading the 422, walking the catalog.

Limitations

What Router does not do today, and what to use instead.

Develop with Comfy

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Specifications

Use Flux.1 Kontext with Comfy Router

Quick start

Schema

Input

Output

Examples

Input

Output

Schema

Input

Output

Examples

Input

Output

Before you ship

Headers

Quick Start

Limitations

​Quick start

​Schema

​Input

​Output

​Examples

​Input

​Output

​Schema

​Input

​Output

​Examples

​Input

​Output

​Before you ship

Headers

Quick Start

Limitations

Quick start

Schema

Input

Output

Examples

Input

Output

Schema

Input

Output

Examples

Input

Output

Before you ship