Flux Kontext

Overview

Flux Kontext is a Black Forest Labs image model for prompt-based image generation and reference-guided image editing. Use this page when you are ready to call the API after trying the model in the APIXO playground.

Capability	Value
Model ID	`flux-kontext`
Modes	`pro`, `max`
Workflows	`text-to-image`, `image-to-image`
Prompt length	1-10000 characters
Reference images	Optional, 1 image URL
Aspect ratios	`1:1`, `4:3`, `3:4`, `9:16`, `16:9`, `21:9`
Output formats	`jpeg`, `png`

Endpoint and authentication

Base URL:

https://api.apixo.ai/api/v1

Method	Endpoint	Purpose
`POST`	`/generateTask/flux-kontext`	Submit a generation task
`GET`	`/statusTask/flux-kontext?taskId={taskId}`	Poll task status and retrieve results

All requests require your APIXO API key:

Authorization: Bearer YOUR_API_KEY

Submit requests also require:

Content-Type: application/json

Copy-paste async quickstart

This minimal request submits a text-to-image task and returns a taskId.

curl -X POST "https://api.apixo.ai/api/v1/generateTask/flux-kontext" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "request_type": "async",
    "input": {
      "mode": "pro",
      "prompt": "a castle on a quiet hill at sunset",
      "aspect_ratio": "16:9",
      "output_format": "jpeg"
    }
  }'

Successful response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678"
  }
}

Save the taskId; you need it to poll for the final result.

Poll for result

curl -X GET "https://api.apixo.ai/api/v1/statusTask/flux-kontext?taskId=task_12345678" \
  -H "Authorization: Bearer YOUR_API_KEY"

Processing response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "processing",
    "createTime": 1767965610929
  }
}

Success response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "success",
    "resultJson": "{\"resultUrls\":[\"https://r2.apixo.ai/xxx.png\"]}",
    "createTime": 1767965610929,
    "completeTime": 1767965652317,
    "costTime": 41388
  }
}

Failed response:

{
  "code": 200,
  "message": "success",
  "data": {
    "taskId": "task_12345678",
    "state": "failed",
    "failCode": "SensitiveContent",
    "failMsg": "Content violates provider policy, please adjust the prompt",
    "createTime": 1767965610929,
    "completeTime": 1767965620132,
    "costTime": 9203
  }
}

Parse resultJson after state becomes success:

const payload = JSON.parse(data.resultJson);
const imageUrls = payload.resultUrls;

Request body

Text-to-image

{
  "request_type": "async",
  "input": {
    "mode": "pro",
    "prompt": "a quiet greenhouse filled with bioluminescent plants",
    "aspect_ratio": "16:9",
    "output_format": "jpeg"
  }
}

Image-to-image

{
  "request_type": "async",
  "input": {
    "mode": "max",
    "prompt": "turn this room into a warm mid-century interior",
    "aspect_ratio": "4:3",
    "image_urls": [
      "https://example.com/source.jpg"
    ],
    "output_format": "png",
    "promptUpsampling": false,
    "safetyTolerance": 2
  }
}

Parameters

request_type

string

default:"async"

Result delivery mode. Use async for polling with statusTask, or callback for webhook delivery.

callback_url

string

Required when request_type is callback. Must be a public HTTPS URL that can receive the final task payload. See Webhooks.

input

object

required

Flux Kontext input parameters.

Show properties

mode

string

required

Model variant used for routing and billing. Supported values: pro, max.

prompt

string

required

Text prompt describing the desired image or edit. Supports 1-10000 characters.

aspect_ratio

string

required

Output aspect ratio. Supported values: 1:1, 4:3, 3:4, 9:16, 16:9, 21:9.

image_urls

string[]

Reference image URLs for image-to-image generation. Optional. If provided, it must contain exactly 1 public, reachable image URL.

image_url

string

Legacy single-image field. Optional. If both image_url and image_urls are provided, image_url takes precedence.

output_format

string

default:"jpeg"

Output image format. Supported values: jpeg, png.

promptUpsampling

boolean

default:"false"

Whether to enable provider-side prompt expansion before generation.

safetyTolerance

integer

default:"2"

Safety tolerance level. Supported values: 0, 1, 2.

watermark

string

Optional custom watermark text. Defaults to an empty string.

enableTranslation

boolean

default:"true"

Whether to enable provider-side prompt translation.

uploadCn

boolean

default:"false"

Advanced provider upload routing flag. Leave it at the default unless APIXO support asks you to change it.

Response format

Submit task response

POST /generateTask/flux-kontext returns a task ID when the task is accepted:

code

integer

API status code. 200 means the task was accepted.

message

string

Human-readable status message.

data.taskId

string

Unique task identifier used with the status endpoint.

Status response fields

taskId

string

Unique task identifier.

state

string

Current task state: pending, processing, success, or failed.

resultJson

string

JSON string containing the generated image URLs. Present when state is success.

failCode

string

Machine-readable failure code. Present when state is failed.

failMsg

string

Human-readable failure message. Present when state is failed.

createTime

integer

Task creation timestamp in Unix milliseconds.

completeTime

integer

Task completion timestamp in Unix milliseconds. Present after completion.

costTime

integer

Processing duration in milliseconds. Present after completion when available.

Webhook callback mode

Use callback mode when your backend should receive the final result automatically instead of polling.

curl -X POST "https://api.apixo.ai/api/v1/generateTask/flux-kontext" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "request_type": "callback",
    "callback_url": "https://your-server.com/webhooks/apixo",
    "input": {
      "mode": "pro",
      "prompt": "a clean product photo of a ceramic lamp on soft stone",
      "aspect_ratio": "1:1",
      "output_format": "jpeg"
    }
  }'

See Webhooks for delivery requirements and retry behavior.

Billing

Flux Kontext is billed per generated image. The selected mode determines the unit price.

Mode	APIXO price	Market reference
`pro`	`$0.03 / image`	`$0.04 / image`
`max`	`$0.06 / image`	`$0.08 / image`

For current route and market comparison pricing, see Pricing.

Latency and polling

Actual latency may vary by prompt complexity, reference image accessibility, provider route, and current queue load.

Mode	Typical generation time	Recommended first poll	Poll interval
`pro`	Around 30s	20s after task creation	3s-5s
`max`	Around 30s or longer	20s after task creation	3s-5s

For high-concurrency production workloads, use callback mode to avoid frequent polling.

Rate limits and concurrency can vary by account, API key, and route. If you receive 429, slow down requests and retry with backoff. For account-level details, see System APIs.

Errors and troubleshooting

HTTP errors

Code	Meaning	What to do
`400`	Invalid request body, missing parameter, unsupported value, or unreachable image URL	Fix the request before retrying
`401`	Missing or invalid API key	Check the `Authorization` header
`402`	Insufficient balance or quota	Add balance or switch account/key
`403`	Key or route cannot access the model	Check permissions and route strategy
`429`	Rate limit or concurrency limit reached	Retry with exponential backoff
`500`	Server error or unmapped provider failure	Retry with backoff
`502`	Upstream provider error	Retry with backoff
`504`	Upstream timeout	Retry or use callback mode for long-running jobs

Parameter validation

Field	Requirement
`input.mode`	Required. Must be `pro` or `max`.
`input.prompt`	Required string. Must not be empty and cannot exceed 10000 characters.
`input.aspect_ratio`	Required. Must be `1:1`, `4:3`, `3:4`, `9:16`, `16:9`, or `21:9`.
`input.image_urls`	Optional array. If present, it cannot be empty and cannot contain more than 1 image URL.
`input.output_format`	Optional. Must be `jpeg` or `png`.
`input.safetyTolerance`	Optional integer. Must be `0`, `1`, or `2`.

Task failure codes

Fail code	Meaning	What to do
`ImageNotAccess`	A reference image URL could not be fetched or was not a public HTTP(S) URL	Use a public, direct image URL
`PromptInvalid`	Prompt was rejected or malformed	Change the prompt and retry
`SensitiveContent`	Prompt or reference image failed provider safety checks	Change the prompt or input image
`RateLimited`	Provider-side rate limit reached	Retry with exponential backoff
`Timeout`	Provider-side timeout	Retry, reduce input complexity, or use callback mode
`Unknown error`	Provider returned an unmapped failure	Retry with backoff or contact support with the `taskId`

See Error Codes for the full error reference.

Getting Started

Image Models

Video Models

Audio Models

Flux Kontext

Overview

Endpoint and authentication

Copy-paste async quickstart

Poll for result

Request body

Text-to-image

Image-to-image

Parameters

Response format

Submit task response

Status response fields

Webhook callback mode

Billing

Latency and polling

Errors and troubleshooting

HTTP errors

Parameter validation

Task failure codes

Getting Started

Image Models

Video Models

Audio Models

Documentation Index

​Overview

​Endpoint and authentication

​Copy-paste async quickstart

​Poll for result

​Request body

​Text-to-image

​Image-to-image

​Parameters

​Response format

​Submit task response

​Status response fields

​Webhook callback mode

​Billing

​Latency and polling

​Errors and troubleshooting

​HTTP errors

​Parameter validation

​Task failure codes

​Related links

Overview

Endpoint and authentication

Copy-paste async quickstart

Poll for result

Request body

Text-to-image

Image-to-image

Parameters

Response format

Submit task response

Status response fields

Webhook callback mode

Billing

Latency and polling

Errors and troubleshooting

HTTP errors

Parameter validation

Task failure codes

Related links