curl --request POST \
  --url https://api.evolink.ai/v1/images/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "doubao-seedream-5.5",
  "prompt": "A serene lake reflecting the beautiful sunset",
  "size": "16:9",
  "quality": "2K"
}
'

{
  "created": 1757165031,
  "id": "task-unified-1793612886-seedream55",
  "model": "doubao-seedream-5.5",
  "object": "image.generation.task",
  "progress": 0,
  "status": "pending",
  "task_info": {
    "can_cancel": true,
    "estimated_time": 45
  },
  "type": "image",
  "usage": {
    "billing_rule": "per_image",
    "credits_reserved": 1.836,
    "user_group": "default"
  }
}

{
  "error": {
    "code": "invalid_request",
    "message": "Invalid request parameters",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired token",
    "type": "authentication_error"
  }
}

{
  "error": {
    "code": "insufficient_quota",
    "message": "Insufficient quota. Please top up your account.",
    "type": "insufficient_quota"
  }
}

{
  "error": {
    "code": "model_access_denied",
    "message": "Token does not have access to model: doubao-seedream-5.5",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests, please try again later",
    "type": "rate_limit_error"
  }
}

{
  "error": {
    "code": "internal_error",
    "message": "Internal server error",
    "type": "api_error"
  }
}

Seedream 5.5

Seedream 5.5 Image Generation

🚧 This model is not yet available, stay tuned

Seedream 5.5 (doubao-seedream-5.5) supports text-to-image, image-to-image and image editing, including transparent backgrounds
Processing is asynchronous. Use the returned task ID to query task status
Generated image links are valid for 24 hours; save them promptly

Billing

Charges are based on the actual number of generated images
Reference images are charged separately from generated images

POST

images

generations

curl --request POST \
  --url https://api.evolink.ai/v1/images/generations \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "model": "doubao-seedream-5.5",
  "prompt": "A serene lake reflecting the beautiful sunset",
  "size": "16:9",
  "quality": "2K"
}
'

{
  "created": 1757165031,
  "id": "task-unified-1793612886-seedream55",
  "model": "doubao-seedream-5.5",
  "object": "image.generation.task",
  "progress": 0,
  "status": "pending",
  "task_info": {
    "can_cancel": true,
    "estimated_time": 45
  },
  "type": "image",
  "usage": {
    "billing_rule": "per_image",
    "credits_reserved": 1.836,
    "user_group": "default"
  }
}

{
  "error": {
    "code": "invalid_request",
    "message": "Invalid request parameters",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or expired token",
    "type": "authentication_error"
  }
}

{
  "error": {
    "code": "insufficient_quota",
    "message": "Insufficient quota. Please top up your account.",
    "type": "insufficient_quota"
  }
}

{
  "error": {
    "code": "model_access_denied",
    "message": "Token does not have access to model: doubao-seedream-5.5",
    "type": "invalid_request_error"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests, please try again later",
    "type": "rate_limit_error"
  }
}

{
  "error": {
    "code": "internal_error",
    "message": "Internal server error",
    "type": "api_error"
  }
}

Authorizations

Authorization

string

header

required

##All APIs require Bearer Token authentication##

Get API Key:

Visit API Key Management Page to get your API Key

Add to request header:

Authorization: Bearer YOUR_API_KEY

Body

application/json

model

enum<string>

default:doubao-seedream-5.5

required

Image generation model name

Available options:

doubao-seedream-5.5

Example:

"doubao-seedream-5.5"

prompt

string

required

Prompt describing the image you want to generate, or describing how to edit the input image

Language support: In addition to Chinese and English, Seedream 5.5 also supports Russian, Arabic, Filipino, Thai, Turkish, Korean, Malay, Spanish, Portuguese, Indonesian, French, German, Vietnamese and Japanese.

Length limit: Up to 4000 tokens (about 2,600 Chinese characters or 5,000 English words); exceeding it returns 400 and is not billed.

Recommendation: Keep prompts under 300 Chinese characters or 600 English words. A longer prompt still fits the limit but dilutes the information, and the model may miss details, leaving elements out of the image.

Example:

"A serene lake reflecting the beautiful sunset"

size

string

default:auto

Size of generated image, supports two formats:

Method 1 - Ratio format:

auto, 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9, 9:21
Works with the quality parameter to automatically generate an image at the corresponding aspect ratio and resolution, without manually specifying pixels

Method 2 - Pixel format:

Width x height, e.g.: 1024x1024, 2048x2048
Total pixel range: [921600, 4624220]
Aspect ratio range: [1/16, 16]
Both width and height must be greater than 14px

Defaults to auto when size is omitted. The model determines the aspect ratio from the prompt, and quality sets the output resolution.

Example:

"16:9"

quality

enum<string>

default:1K

Output resolution, used with the aspect ratio format of size. Defaults to 1K.

Aspect ratio	1K	1.5K	2K
`1:1`	1024×1024	1536×1536	2048×2048
`2:3`	832×1248	1248×1872	1664×2496
`3:2`	1248×832	1872×1248	2496×1664
`3:4`	864×1152	1344×1792	1776×2368
`4:3`	1152×864	1792×1344	2368×1776
`4:5`	896×1120	1344×1680	1792×2240
`5:4`	1120×896	1680×1344	2240×1792
`9:16`	800×1424	1152×2048	1584×2816
`16:9`	1424×800	2048×1152	2816×1584
`21:9`	1568×672	2352×1008	3136×1344
`9:21`	672×1568	1008×2352	1344×3136

Available options:

1K,

1.5K,

2K

Example:

"2K"

prompt_priority

enum<string>

default:standard

Prompt optimization mode. Only standard is supported and is the default.

Passing fast returns 400 with no charge.

Available options:

standard

Example:

"standard"

image_urls

string<uri>[]

Reference image URL list for image-to-image and image editing features

Note:

Reference images are charged separately from generated images
Single request supports input image quantity: 10 images
Image size: no more than 30MB
Supported image formats: .jpeg, .jpg, .png, .webp, .bmp, .tiff, .gif, .heic, .heif
Aspect ratio (width/height) range: [1/16, 16]
Width and height (px) > 14
Total pixels: [196, 6000×6000]
Image URLs must be directly viewable by the server, or the image URL should trigger direct download when accessed (typically these URLs end with image file extensions, such as .png, .jpg)

Maximum array length: 10

Example:

[
  "https://example.com/image1.png",
  "https://example.com/image2.png"
]

output_format

enum<string>

default:png

Output image format

Options:

png: PNG format (default)
jpeg: JPEG format

Note: With background=transparent, output is always png: omitting output_format automatically produces png, while specifying jpeg is rejected.

Available options:

png,

jpeg

Example:

"png"

watermark

boolean

default:false

Whether to add a watermark to the generated image

Example:

false

background

enum<string>

default:auto

Output background type. Defaults to auto.

Options:

auto: The model determines the background from the prompt and reference images. result_data[].background in the task detail returns the actual type: transparent or opaque
transparent: Generate a PNG image with an alpha channel. Supported for both text-to-image and image-to-image
opaque: Generate an image with an opaque background

When using transparent:

Reference images are optional. If provided, up to 10 are supported and they do not need an alpha channel
Output must be png. Omitting output_format uses png automatically; passing jpeg returns an error

Available options:

auto,

transparent,

opaque

Example:

"auto"

callback_url

string<uri>

HTTPS callback address after task completion

Callback Timing:

Triggered when task is completed, failed, or cancelled
Sent after billing confirmation is completed

Security Restrictions:

Only HTTPS protocol is supported
Callback to internal IP addresses is prohibited (127.0.0.1, 10.x.x.x, 172.16-31.x.x, 192.168.x.x, etc.)
URL length must not exceed 2048 characters

Callback Mechanism:

Timeout: 10 seconds
Maximum 3 retries on failure (retries after 1 second/2 seconds/4 seconds)
Callback response body format is consistent with the task query API response format
Callback address returning 2xx status code is considered successful, other status codes will trigger retry

Example:

"https://your-domain.com/webhooks/image-task-completed"

Response

Image generation task created successfully

created

integer

Task creation timestamp

Example:

1757165031

string

Task ID

Example:

"task-unified-1793612886-seedream55"

model

string

Actual model name used

Example:

"doubao-seedream-5.5"

object

enum<string>

Specific task type

Available options:

image.generation.task

progress

integer

Task progress percentage (0-100)

Required range: 0 <= x <= 100

Example:

0

status

enum<string>

Task status

Available options:

pending,

processing,

completed,

failed

Example:

"pending"

task_info

object

Async task information

Show child attributes

type

enum<string>

Task output type

Available options:

text,

image,

audio,

video

Example:

"image"

usage

object

Usage and billing information

Show child attributes

Image Series

Video Series

Audio Series

Text Series

Account Management

Task Management

File Management

Seedream 5.5 Image Generation

Billing

Authorizations

Body

Response