Seedream 5.5

ByteDance's newest image model: stable across 100 rounds of edits, more realistic photos and sharper small text

Model ID	Alias	Endpoint
`bytedance/seedream-5.5`	`seedream-5.5`	Image generation

Input modes

Mode	References	Reference roles
`text` Text only	—	—
`image` Image input	1 to 10	`reference_image`

Prompt limit: 5,000 characters; longer prompts are rejected with 400.

Parameters

Parameter	Description	Values	Default	Required
`resolution`	Resolution: Output resolution.	`1K`, `2K`	`1K`	No
`aspect_ratio`	Aspect ratio: Output aspect ratio.	`1:1`, `4:3`, `3:4`, `16:9`, `9:16`, `3:2`, `2:3`, `2:1`, `1:2`, `21:9`	`1:1`	No
`n`	Outputs per request: Number of outputs from one API request (one Job), not the application batch size. For multiple Jobs, submit separate requests; n=1 does not prevent application-managed batching.	`1`	`1`	No

Examples

text input:

{
  "model": "bytedance/seedream-5.5",
  "input": {
    "type": "text",
    "prompt": "A watercolor fox reading a map in a pine forest"
  },
  "parameters": {
    "resolution": "1K",
    "aspect_ratio": "1:1",
    "n": 1
  }
}

image input:

{
  "model": "bytedance/seedream-5.5",
  "input": {
    "type": "image",
    "prompt": "A watercolor fox reading a map in a pine forest",
    "references": [
      {
        "role": "reference_image",
        "file_id": "file_..."
      }
    ]
  },
  "parameters": {
    "resolution": "1K",
    "aspect_ratio": "1:1",
    "n": 1
  }
}

The authoritative contract is GET /v1/models/bytedance/seedream-5.5?view=contract. A valid parameter does not mean every channel can run it, so quote the complete request. Prices and channels are listed in Model Market.