Skip to main content
Doubao-Seed-2.1-Turbo balances quality and cost, available through Anyfast via an OpenAI-compatible interface. It fully upgrades coding, agent, and multimodal capabilities over the previous generation, and is built for scaled production workloads that need to handle large volumes of online calls reliably — with the same capability surface as Doubao-Seed-2.1-Pro.

Key capabilities

  • OpenAI-compatible — Works as a drop-in replacement with the OpenAI SDK
  • 256K context window — Handles project-scale context, with up to 256K tokens of output in a single response
  • Quality/cost balance — Built for large-scale, standardized production workloads
  • Deep thinking — Chain-of-thought reasoning, on by default, with adjustable reasoning_effort
  • Multimodal understanding — Text, image, video, and document understanding (audio not supported)
  • Function calling, structured output & context caching — Robust tool use, JSON output (beta), and prompt caching
  • Streaming — Real-time token streaming via SSE

Output specifications

PropertyValue
Input modalityText, Image, Video, Document
Output modalityText
Context window256K tokens
Max output tokens256K

Quick example

curl https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seed-2.1-turbo",
    "messages": [
      { "role": "user", "content": "Explain quantum entanglement in simple terms." }
    ]
  }'

Thinking mode

Doubao-Seed-2.1-Turbo reasons before answering by default. thinking.type is enabled unless you set it to disabled to skip reasoning for lightweight tasks. Use reasoning_effort to tune how long the model thinks.
Python
response = client.chat.completions.create(
    model="doubao-seed-2.1-turbo",
    messages=[
        {"role": "user", "content": "Design a REST API for a blogging platform."}
    ],
    extra_body={
        "thinking": {"type": "enabled"},
        "reasoning_effort": "high"
    }
)

print(response.choices[0].message.content)
reasoning_effort controls reasoning length (effective only when thinking is enabled) and accepts minimal, low, medium, and high. Default: high.

Parameters

ParameterTypeRequiredDescription
modelstringYesMust be doubao-seed-2.1-turbo
messagesarrayYesList of { role, content } objects
thinkingobjectNo{ "type": "enabled" | "disabled" }. Controls deep thinking. Default: enabled
reasoning_effortstringNominimal, low, medium, high. Effective when thinking is enabled. Default: high
max_tokensintegerNoMaximum tokens to generate (up to 262144)
temperaturefloatNo02. Controls randomness. Default: 1
top_pfloatNoNucleus sampling threshold. Default: 1
streambooleanNoEnable SSE streaming. Default: false
toolsarrayNoFunction tool definitions for tool use
response_formatobjectNo{ "type": "json_object" } for structured JSON output (beta)
stopstring / arrayNoSequences that stop generation

API Reference

View the interactive API playground for Doubao Seed 2.1 Turbo.