Seedream 4.5

Overview

Seedream 4.5 is a ByteDance image model for text-to-image generation and reference-guided image generation. It supports 2K and 4K output presets, up to 10 generated images per task, optional sequential generation, and flexible size input for callers who prefer explicit dimensions.

Capability	Value
Model ID	`seedream-4-5`
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	`2K`, `4K`
Aspect ratios	`1:1`, `2:3`, `3:2`, `4:3`, `3:4`, `9:16`, `16:9`, `21:9`
Size input	`2K`, `4K`, `2048x2048`, `2048X2048`, `2048*2048`
Sequential generation	`disabled`, `auto`
Prompt optimization	`standard`

Endpoint and authentication

Base URL:

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

Method	Endpoint	Purpose
`POST`	`/generateTask/seedream-4-5`	Submit a generation task
`GET`	`/statusTask/seedream-4-5?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-4-5" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": {
      "mode": "text-to-image",
      "prompt": "a cozy cyberpunk cafe with warm neon lights, ultra detailed",
      "max_images": 2,
      "resolution": "2K",
      "aspect_ratio": "16:9",
      "prompt_optimize_mode": "standard"
    }
  }'

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/seedream-4-5?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://file.apixo.ai/img1.png\",\"https://file.apixo.ai/img2.png\"]}",
    "createTime": 1767965610929,
    "completeTime": 1767965652317,
    "costTime": 41388
  }
}

Request body

Text-to-image

{
  "input": {
    "mode": "text-to-image",
    "prompt": "a fox in watercolor style",
    "max_images": 1,
    "resolution": "2K",
    "aspect_ratio": "1:1",
    "sequential_image_generation": "disabled",
    "prompt_optimize_mode": "standard"
  }
}

Image-to-image

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

Explicit size

{
  "input": {
    "mode": "text-to-image",
    "prompt": "an editorial still life scene",
    "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 4.5 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. This field is required; the backend does not apply a default.

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: 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. Supports 2K, 4K, and pixel strings such as 2048x2048, 2048X2048, or 2048*2048. Custom sizes may be normalized to the nearest supported value.

sequential_image_generation

string

default:"disabled"

Sequential image mode. Supported values: disabled, auto. Use auto when multiple images should be generated as a related sequence.

prompt_optimize_mode

string

default:"standard"

Prompt optimization mode. Seedream 4.5 currently supports standard.

Size presets from `resolution + aspect_ratio`

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

Aspect ratio	`2K` size	`4K` size
`1:1`	`2048x2048`	`4096x4096`
`2:3`	`1664x2496`	`3328x4992`
`3:2`	`2496x1664`	`4992x3328`
`3:4`	`1728x2304`	`3520x4704`
`4:3`	`2304x1728`	`4704x3520`
`9:16`	`1600x2848`	`3040x5504`
`16:9`	`2848x1600`	`5504x3040`
`21:9`	`3136x1344`	`6240x2656`

Response format

Submit task response

POST /generateTask/seedream-4-5 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

Task identifier used for later polling or webhook matching.

Status response

data.state

string

Task state. Common values are processing, success, and failed.

data.resultJson

string

Present on success. Parse this JSON string and read resultUrls.

data.failCode

string

Present on failure. Stable machine-readable failure code.

data.failMsg

string

Present on failure. Human-readable failure message.

Polling and delivery guidance

Seedream 4.5 tasks are asynchronous.

Resolution	Typical generation time	Recommended first poll	Poll interval
`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 4.5 is billed per generated image. The current public APIXO price is a single flat rate for this model.

Unit	APIXO price
Per generated image	`$0.0350 / 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

​Poll for result

​Request body

​Text-to-image

​Image-to-image

​Explicit size

​Parameters

​Size presets from resolution + aspect_ratio

​Response format

​Submit task response

​Status response

​Polling and delivery guidance

​Billing

Overview

Endpoint and authentication

Copy-paste async quickstart

Poll for result

Request body

Text-to-image

Image-to-image

Explicit size

Parameters

Size presets from `resolution + aspect_ratio`

Response format

Submit task response

Status response

Polling and delivery guidance

Billing