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
• Deep thinking — Chain-of-thought reasoning, on by default, with adjustable reasoning_effort
• Strong coding & agents — Requirement understanding, long-horizon planning, continuous repair, and engineering delivery
• 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

​

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-pro",
    "messages": [
      { "role": "user", "content": "Explain quantum entanglement in simple terms." }
    ]
  }'

​

Thinking mode

response = client.chat.completions.create(
    model="doubao-seed-2.1-pro",
    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)

​

Parameters