Seedream 4.0

Overview

Seedream 4.0 is a ByteDance image model for text-to-image generation and reference-guided image generation. It supports 1K, 2K, and 4K output presets, up to 10 generated images per task, optional sequential generation, and prompt optimization with standard or fast.

Capability	Value
Model ID	`seedream-4-0`
Modes	`text-to-image`, `image-to-image`
Prompt length	1-5000 characters
Reference images	1-14 URLs for `image-to-image`
Images per task	`max_images` is required, 1-10
Resolution tiers	`1K`, `2K`, `4K`
Aspect ratios	`1:1`, `2:3`, `3:2`, `4:3`, `3:4`, `9:16`, `16:9`, `21:9`
Size input	`1K`, `2K`, `4K`, `2048x2048`, `2048X2048`, `2048*2048`
Sequential generation	`disabled`, `auto`
Prompt optimization	`standard`, `fast`

Endpoint and authentication

Base URL:

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

Method	Endpoint	Purpose
`POST`	`/generateTask/seedream-4-0`	Submit a generation task
`GET`	`/statusTask/seedream-4-0?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/seedream-4-0" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": {
      "mode": "text-to-image",
      "prompt": "a sunrise train passing through snowy hills",
      "max_images": 2,
      "resolution": "1K",
      "aspect_ratio": "16:9",
      "prompt_optimize_mode": "fast"
    }
  }'

Successful response:

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

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

Request body

Text-to-image

{
  "input": {
    "mode": "text-to-image",
    "prompt": "a clean architectural concept of a coastal library",
    "max_images": 2,
    "resolution": "1K",
    "aspect_ratio": "16:9",
    "prompt_optimize_mode": "fast"
  }
}

Image-to-image

{
  "input": {
    "mode": "image-to-image",
    "prompt": "turn this sketch into a cinematic concept frame",
    "image_urls": [
      "https://example.com/reference-1.png"
    ],
    "max_images": 2,
    "resolution": "2K",
    "aspect_ratio": "3:4",
    "sequential_image_generation": "auto",
    "prompt_optimize_mode": "standard"
  }
}

Explicit size

{
  "input": {
    "mode": "text-to-image",
    "prompt": "an editorial interior still",
    "max_images": 1,
    "size": "2048*2048"
  }
}

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

Seedream 4.0 input parameters.

Show properties

mode

string

required

Generation mode. Supported values: text-to-image, image-to-image.

prompt

string

required

Text prompt describing the desired image or edit. Supports 1-5000 characters after trimming whitespace.

max_images

integer

required

Number of images to request. Supported range: 1-10.

image_urls

string[]

Reference image URLs. Required for image-to-image. Supports 1-14 URLs. URLs should be public, directly accessible image files.

resolution

string

default:"2K"

Output resolution preset. Supported values: 1K, 2K, 4K. When resolution + aspect_ratio and size are both provided, resolution + aspect_ratio takes precedence.

aspect_ratio

string

Optional output aspect ratio. Supported values: 1:1, 2:3, 3:2, 4:3, 3:4, 9:16, 16:9, 21:9.

size

string

Optional explicit size or preset token. Preset tokens are case-insensitive and support 1K, 2K, and 4K. Pixel strings accept x, X, or * separators, such as 2048x2048, 2048X2048, or 2048*2048. Custom pixel sizes must use 16-pixel granularity, keep aspect ratio between 1/16 and 16, and keep total pixels between 921,600 and 16,777,216 (1280x720 to 4096x4096 equivalent). Unsupported custom values may be adjusted to the nearest supported output size.

sequential_image_generation

string

default:"disabled"

Sequential image mode. Supported values: disabled, auto.

prompt_optimize_mode

string

default:"standard"

Prompt optimization mode. Supported values: standard, fast.

Size presets from `resolution + aspect_ratio`

When aspect_ratio is provided, APIXO maps resolution and aspect_ratio to these output dimensions:

Aspect ratio	`1K` size	`2K` size	`4K` size
`1:1`	`1024x1024`	`2048x2048`	`4096x4096`
`2:3`	`832x1248`	`1664x2496`	`3328x4992`
`3:2`	`1248x832`	`2496x1664`	`4992x3328`
`3:4`	`864x1152`	`1728x2304`	`3520x4704`
`4:3`	`1152x864`	`2304x1728`	`4704x3520`
`9:16`	`736x1312`	`1600x2848`	`3040x5504`
`16:9`	`1312x736`	`2848x1600`	`5504x3040`
`21:9`	`1568x672`	`3136x1344`	`6240x2656`

Polling and delivery guidance

Seedream 4.0 tasks are asynchronous.

Resolution	Typical generation time	Recommended first poll	Poll interval
`1K`	20s-30s	15s after task creation	3s
`2K`	25s-35s	20s after task creation	3s-5s
`4K`	40s-55s	30s after task creation	5s

For production systems, prefer callback_url instead of tight polling loops.

Billing

Seedream 4.0 is billed per generated image. The current public APIXO price is a single flat rate for this model.

Unit	APIXO price
Per generated image	`$0.0290 / image`

Billing behavior:

precharge = requested max_images * unit price
final charge = successful images * unit price

If fewer images succeed than requested, APIXO automatically adjusts the final charge to the actual number of successful outputs.

​Overview

​Endpoint and authentication

​Copy-paste async quickstart

​Request body

​Text-to-image

​Image-to-image

​Explicit size

​Parameters

​Size presets from resolution + aspect_ratio

​Polling and delivery guidance

​Billing

Overview

Endpoint and authentication

Copy-paste async quickstart

Request body

Text-to-image

Image-to-image

Explicit size

Parameters

Size presets from `resolution + aspect_ratio`

Polling and delivery guidance

Billing