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AnyFast is compatible with the Volcengine Ark Chat API. If you’re already using the Ark SDK or calling the Ark API directly, switching to AnyFast requires only a base URL change — no code rewrite needed.

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Endpoints

POST https://www.anyfast.ai/v1/chat/completions
POST https://www.anyfast.ai/v1/responses

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Authentication

Authorization: Bearer YOUR_API_KEY

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Supported models

ModelDescription
doubao-seed-2.0-proDoubao Seed 2.0 Pro — most capable
doubao-seed-2.0-codeDoubao Seed 2.0 Code — optimized for coding
doubao-seed-2.0-liteDoubao Seed 2.0 Lite — balanced
doubao-seed-2.0-miniDoubao Seed 2.0 Mini — fast and lightweight
doubao-seed-1-8-251228Doubao Seed 1.8
doubao-seed-1-6-flash-250828Doubao Seed 1.6 Flash — fast inference
doubao-seed-1-6-251015Doubao Seed 1.6
doubao-seed-1-6-lite-251015Doubao Seed 1.6 Lite
doubao-seed-1-6-vision-250815Doubao Seed 1.6 Vision — multimodal
glm-4-7-251222GLM-4-7

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Supported input types

ContentChat API typeChat API data fieldResponses API typeResponses API data field
Texttexttextinput_texttext
Imageimage_urlimage_url.urlinput_imageimage_url (string)
Videovideo_urlvideo_url.url + video_url.fpsinput_videovideo_url (string) + fps
Document——input_filefile_url or file_data + filename
All content types support both URL and Base64 data URI formats.

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Features

  • Streaming — Set stream: true for real-time token streaming via SSE
  • Function calling — Use the tools and tool_choice parameters
  • Reasoning — Models return reasoning_content with chain-of-thought
  • Vision — Send images via image_url / input_image content blocks
  • Video understanding — Send videos via video_url / input_video with optional fps control
  • Document understanding — Send PDF/documents via input_file (Responses API only)
  • Multi-turn conversations — Include full message history in messages / input

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Chat Completions API

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Text

curl https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-2.0-pro",
    "messages": [
      {"role": "user", "content": "Hello!"}
    ]
  }'

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Image (URL)

cURL
curl https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-1-6-251015",
    "messages": [
      {
        "role": "user",
        "content": [
          {"type": "image_url", "image_url": {"url": "https://example.com/photo.jpg"}},
          {"type": "text", "text": "What is in this image?"}
        ]
      }
    ],
    "max_tokens": 100
  }'

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Image (Base64)

cURL
curl https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-1-6-251015",
    "messages": [
      {
        "role": "user",
        "content": [
          {"type": "image_url", "image_url": {"url": "data:image/png;base64,{BASE64_IMAGE}"}},
          {"type": "text", "text": "What is in this image?"}
        ]
      }
    ]
  }'

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Video (URL + fps)

The fps parameter controls frame extraction rate (frames per second). Default: 1, range: 0.2–5.
cURL
curl https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-1-6-251015",
    "messages": [
      {
        "role": "user",
        "content": [
          {"type": "video_url", "video_url": {"url": "https://example.com/clip.mp4", "fps": 2}},
          {"type": "text", "text": "What buildings appear in this video?"}
        ]
      }
    ],
    "max_tokens": 200
  }'

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Video (Base64)

cURL
curl https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-1-6-251015",
    "messages": [
      {
        "role": "user",
        "content": [
          {"type": "video_url", "video_url": {"url": "data:video/mp4;base64,{BASE64_VIDEO}"}},
          {"type": "text", "text": "What is in this video?"}
        ]
      }
    ]
  }'

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Responses API

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Text

cURL
curl https://www.anyfast.ai/v1/responses \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-2.0-pro",
    "input": "Hello!"
  }'

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Image (URL)

cURL
curl https://www.anyfast.ai/v1/responses \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-1-6-251015",
    "input": [
      {
        "role": "user",
        "content": [
          {"type": "input_image", "image_url": "https://example.com/photo.jpg"},
          {"type": "input_text", "text": "What is in this image?"}
        ]
      }
    ]
  }'

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Video (URL + fps)

cURL
curl https://www.anyfast.ai/v1/responses \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-1-6-251015",
    "input": [
      {
        "role": "user",
        "content": [
          {"type": "input_video", "video_url": "https://example.com/clip.mp4", "fps": 1},
          {"type": "input_text", "text": "What is in this video?"}
        ]
      }
    ]
  }'

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Document (URL)

Document understanding is only available via the Responses API.
cURL
curl https://www.anyfast.ai/v1/responses \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-2.0-lite",
    "input": [
      {
        "role": "user",
        "content": [
          {"type": "input_file", "file_url": "https://example.com/document.pdf"},
          {"type": "input_text", "text": "Summarize this document"}
        ]
      }
    ]
  }'

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Document (Base64)

cURL
curl https://www.anyfast.ai/v1/responses \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-2.0-lite",
    "input": [
      {
        "role": "user",
        "content": [
          {"type": "input_file", "file_data": "data:application/pdf;base64,{BASE64_PDF}", "filename": "document.pdf"},
          {"type": "input_text", "text": "Summarize this document"}
        ]
      }
    ]
  }'

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fps parameter

fpsUse case
0.2–0.5Static scenes, surveillance footage
1 (default)General purpose
2–5Fast action, sports, motion counting

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File size limits

MethodImageVideoDocument
URL< 10 MB< 50 MB< 50 MB
Base64< 10 MB (body < 64 MB)< 50 MB (body < 64 MB)< 50 MB (body < 64 MB)

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Streaming example

stream = client.chat.completions.create(
    model="doubao-seed-2.0-pro",
    messages=[
        {"role": "user", "content": "Write a short poem"}
    ],
    stream=True
)

for chunk in stream:
    if chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="")