> ## Documentation Index
> Fetch the complete documentation index at: https://docs.anyfast.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Doubao Seed Evolving

> ByteDance's Doubao-Seed-Evolving model via OpenAI-compatible API. A single, always-latest model ID that updates weekly — currently equivalent to Doubao-Seed-2.1-Pro.

Doubao-Seed-Evolving gives you ByteDance's strongest available Seed model through a single, stable model ID, available through Anyfast via an OpenAI-compatible interface. It updates on a weekly cadence and continuously evolves — upgrades take effect automatically, so you never need to switch model IDs or rework your integration. It currently maps to Doubao-Seed-2.1-Pro, and targets coding, office, and productivity scenarios.

<Note>
  Doubao-Seed-Evolving does not support batch inference. For batch workloads, use a versioned model such as `doubao-seed-2.1-pro` or `doubao-seed-2.1-turbo`.
</Note>

## Key capabilities

* **OpenAI-compatible** — Works as a drop-in replacement with the OpenAI SDK
* **Always latest** — One model ID points to the strongest version, updated weekly with no migration
* **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`
* **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

| Property          | Value                        |
| ----------------- | ---------------------------- |
| Input modality    | Text, Image, Video, Document |
| Output modality   | Text                         |
| Context window    | 256K tokens                  |
| Max output tokens | 256K                         |

## Quick example

<CodeGroup>
  ```bash cURL theme={null}
  curl https://www.anyfast.ai/v1/chat/completions \
    -H "Authorization: Bearer YOUR_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "model": "doubao-seed-evolving",
      "messages": [
        { "role": "user", "content": "Explain quantum entanglement in simple terms." }
      ]
    }'
  ```

  ```python Python theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="YOUR_API_KEY",
      base_url="https://www.anyfast.ai/v1"
  )

  response = client.chat.completions.create(
      model="doubao-seed-evolving",
      messages=[
          {"role": "user", "content": "Explain quantum entanglement in simple terms."}
      ]
  )

  print(response.choices[0].message.content)
  ```

  ```python Streaming theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="YOUR_API_KEY",
      base_url="https://www.anyfast.ai/v1"
  )

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

  for chunk in stream:
      print(chunk.choices[0].delta.content or "", end="")
  ```
</CodeGroup>

## Thinking mode

Doubao-Seed-Evolving 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 Python theme={null}
response = client.chat.completions.create(
    model="doubao-seed-evolving",
    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

| Parameter          | Type           | Required | Description                                                                             |
| ------------------ | -------------- | -------- | --------------------------------------------------------------------------------------- |
| `model`            | string         | Yes      | Must be `doubao-seed-evolving`                                                          |
| `messages`         | array          | Yes      | List of `{ role, content }` objects                                                     |
| `thinking`         | object         | No       | `{ "type": "enabled" \| "disabled" }`. Controls deep thinking. Default: `enabled`       |
| `reasoning_effort` | string         | No       | `minimal`, `low`, `medium`, `high`. Effective when thinking is enabled. Default: `high` |
| `max_tokens`       | integer        | No       | Maximum tokens to generate (up to 262144)                                               |
| `temperature`      | float          | No       | `0`–`2`. Controls randomness. Default: `1`                                              |
| `top_p`            | float          | No       | Nucleus sampling threshold. Default: `1`                                                |
| `stream`           | boolean        | No       | Enable SSE streaming. Default: `false`                                                  |
| `tools`            | array          | No       | Function tool definitions for tool use                                                  |
| `response_format`  | object         | No       | `{ "type": "json_object" }` for structured JSON output (beta)                           |
| `stop`             | string / array | No       | Sequences that stop generation                                                          |

<Card title="API Reference" icon="code" href="/api-reference/model-api/bytedance/doubao-seed-evolving">
  View the interactive API playground for Doubao Seed Evolving.
</Card>

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