Image Generation or Editing Callbacks

When the image generation task is completed, the system will send the result to your provided callback URL via POST request

When you submit an image generation or editing task to the Flux Kontext API, you can use the callBackUrl parameter to set a callback URL. The system will automatically push the results to your specified address when the task is completed.

Callback Mechanism Overview

The callback mechanism eliminates the need to poll the API for task status. The system will proactively push task completion results to your server.

Callback Timing

The system will send callback notifications in the following situations:

Image generation or editing task completed successfully

Image generation or editing task failed

Errors occurred during task processing

Callback Method

HTTP Method: POST

Content Type: application/json

Timeout Setting: 15 seconds

Callback Request Format

When the task is completed, the system will send a POST request to your callBackUrl in the following format:

Success Callback

Content Policy Violation Callback

Generation Failure Callback

Internal Error Callback

{
  "code": 200,
  "msg": "BFL image generated successfully.",
  "data": {
    "taskId": "task12345",
    "info": {
      "originImageUrl": "https://example.com/original.jpg",
      "resultImageUrl": "https://example.com/result.jpg"
    }
  }
}

Status Code Description

`code` (integer, required)

Callback status code indicating task processing result:

Status Code	Description
200	Success - Image generation completed successfully
400	Failed - Your prompt was flagged by Website as violating content policies
500	Failed - Internal Error, Please try again later
501	Failed - Image generation task failed

`msg` (string, required)

Status message providing detailed status description

`data.taskId` (string, required)

Task ID, consistent with the taskId returned when you submitted the task

`data.info.originImageUrl` (string)

Original image URL, valid for 10 minutes. Only present on success.

`data.info.resultImageUrl` (string)

Generated image URL on our server. Only present on success.

Callback Reception Examples

Here are example codes for receiving callbacks in popular programming languages:

Node.js

Python

PHP

Best Practices

Callback URL Configuration Recommendations

Use HTTPS: Ensure your callback URL uses HTTPS protocol for secure data transmission

Verify Source: Verify the legitimacy of the request source in callback processing

Idempotent Processing: The same taskId may receive multiple callbacks, ensure processing logic is idempotent

Quick Response: Callback processing should return a 200 status code as quickly as possible to avoid timeout

Asynchronous Processing: Complex business logic should be processed asynchronously to avoid blocking callback response

Timely Download: Original image URLs are valid for only 10 minutes, download and save files promptly upon success

Important Reminders

Callback URL must be a publicly accessible address

Server must respond within 15 seconds, otherwise it will be considered a timeout

If 3 consecutive retries fail, the system will stop sending callbacks

Original image URLs expire after 10 minutes - download immediately upon receiving callback

Please ensure the stability of callback processing logic to avoid callback failures due to exceptions

Need to handle multiple error status codes (400, 500, 501) for complete error handling

Pay attention to content policy violations and adjust prompts accordingly

Troubleshooting

If you do not receive callback notifications, please check the following:

Network Connection Issues

Confirm that the callback URL is accessible from the public network

Check firewall settings to ensure inbound requests are not blocked

Verify that domain name resolution is correct

Server Response Issues

Ensure the server returns HTTP 200 status code within 15 seconds

Check server logs for error messages

Verify that the interface path and HTTP method are correct

Content Format Issues

Confirm that the received POST request body is in JSON format

Check that Content-Type is application/json

Verify that JSON parsing is correct

Image Processing Issues

Confirm that image URLs are accessible

Check image download permissions and network connections

Verify image save paths and permissions

Note the 10-minute original image URL expiration - implement prompt download logic

Handle both generated and original image downloads

Content Policy Issues

Review error messages for content policy violations

Adjust prompts that are flagged by content moderation

Ensure prompts comply with platform content guidelines

Check for sensitive or inappropriate content

Task Failure Issues

Check if generation parameters are reasonable

Verify input image format and quality

Confirm prompt length and format

Consider adjusting generation parameters and retry

Alternative Solution

If you cannot use the callback mechanism, you can also use polling:

Poll Query Results

Use the get image details endpoint to regularly query task status. We recommend querying every 30 seconds.

Image Generation or Editing Callbacks

Callback Mechanism Overview#

Callback Timing#

Callback Method#

Callback Request Format#

Status Code Description#

code (integer, required)#

msg (string, required)#

data.taskId (string, required)#

data.info.originImageUrl (string)#

data.info.resultImageUrl (string)#

Callback Reception Examples#

Best Practices#

Callback URL Configuration Recommendations#

Important Reminders#

Troubleshooting#

Alternative Solution#

Callback Mechanism Overview

Callback Timing

Callback Method

Callback Request Format

Status Code Description

`code` (integer, required)

`msg` (string, required)

`data.taskId` (string, required)

`data.info.originImageUrl` (string)

`data.info.resultImageUrl` (string)

Callback Reception Examples

Best Practices

Callback URL Configuration Recommendations

Important Reminders

Troubleshooting

Alternative Solution