> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apiyi.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Seed 2.1 Turbo Chat API Reference
> Seed 2.1 Turbo (dola-seed-2-1-turbo-260628) Chat Completions API reference and interactive playground: OpenAI-compatible, with thinking toggle and tiers.
Use the Playground on the right: put `Bearer sk-your-api-key` in **Authorization**. The default example has deep thinking disabled (`thinking.disabled`) so you get a fast response on the first send.
The model has **deep thinking ON by default** — even simple questions produce hundreds of reasoning tokens first. Keep `"thinking": {"type": "disabled"}` from the example while debugging; switch to `reasoning_effort` (low / medium / high) when you actually need reasoning. Capabilities, pricing, and caching are covered in the [Seed 2.1 Turbo Overview](/en/api-capabilities/dola-seed-2-1-turbo/overview).
* With thinking on, give `max_tokens` headroom (reasoning counts against the output budget) — 3000+ recommended
* A misspelled model name returns **503** (no available channel), not 404
## Parameter Quick Reference
| Parameter | Type | Required | Default | Notes |
| ------------------ | ------ | -------- | --------- | -------------------------------------------------------------------------------- |
| `model` | string | ✓ | — | Fixed: `dola-seed-2-1-turbo-260628` |
| `messages` | array | ✓ | — | Standard OpenAI message array |
| `max_tokens` | int | | — | Output budget; 3000+ with thinking on |
| `thinking.type` | string | | `enabled` | **ON by default**; `disabled` turns thinking off |
| `reasoning_effort` | string | | — | `low` / `medium` / `high`; measured \~226 (low) vs \~960 (high) reasoning tokens |
| `stream` | bool | | `false` | SSE streaming; add `stream_options.include_usage` for usage |
| `response_format` | object | | — | Structured output, supports `json_schema` + `strict` |
| `tools` | array | | — | Function-calling tool list |
## Response Highlights
* With thinking on, `choices[0].message` carries `reasoning_content` (full reasoning text) besides `content`
* Thinking spend: `usage.completion_tokens_details.reasoning_tokens`
* Implicit cache hits: `usage.prompt_tokens_details.cached_tokens` (a repeated long prefix hits from the 2nd request)
## OpenAPI
````yaml api-reference/dola-seed-2-1-turbo-chat-openapi-en.yaml POST /v1/chat/completions
openapi: 3.1.0
info:
title: Seed 2.1 Turbo Chat Completions API
description: >
ByteDance Seed 2.1 Turbo (`dola-seed-2-1-turbo-260628`) — OpenAI-compatible
Chat Completions endpoint.
- **Deep thinking is ON by default**: without extra params the model returns
`reasoning_content` and burns extra tokens; pass `thinking: {"type":
"disabled"}` for latency/cost-sensitive calls
- Supports `reasoning_effort` tiers (low / medium / high) to control
thinking depth
- Supports structured output (`response_format: json_schema`), function
calling, and streaming
- Implicit caching is automatic: a repeated long prefix hits `cached_tokens`
from the 2nd request
**Authentication**: add `Authorization: Bearer YOUR_API_KEY` header
**Get an API Key**: create a token in the APIYI console at
`api.apiyi.com/token`
version: 1.0.0
servers:
- url: https://api.apiyi.com
description: Primary endpoint
- url: https://vip.apiyi.com
description: Backup endpoint
security:
- bearerAuth: []
paths:
/v1/chat/completions:
post:
tags:
- Text Generation
summary: Chat completion with Seed 2.1 Turbo
description: >
Run chat completions with `dola-seed-2-1-turbo-260628`, fully
OpenAI-compatible.
- Deep thinking is enabled by default and adds a `reasoning_content`
field; the example disables it for fast debugging
- With thinking enabled, give `max_tokens` generous headroom (reasoning
counts against it)
operationId: createSeedChatCompletion
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/SeedChatRequest'
example:
model: dola-seed-2-1-turbo-260628
messages:
- role: user
content: Introduce yourself in one sentence
max_tokens: 500
thinking:
type: disabled
responses:
'200':
description: Chat completion succeeded
content:
application/json:
schema:
$ref: '#/components/schemas/SeedChatResponse'
'400':
description: Invalid parameters (e.g. malformed json_schema, wrong types)
'401':
description: Unauthorized - invalid API Key
'429':
description: Rate limit exceeded or insufficient balance
'503':
description: >-
Wrong model name or no available channel for your group (this model
returns 503 instead of 404 for unknown model names)
security:
- bearerAuth: []
components:
schemas:
SeedChatRequest:
type: object
required:
- model
- messages
properties:
model:
type: string
description: Model ID, fixed to dola-seed-2-1-turbo-260628
enum:
- dola-seed-2-1-turbo-260628
default: dola-seed-2-1-turbo-260628
messages:
type: array
description: Conversation messages, standard OpenAI format
items:
type: object
required:
- role
- content
properties:
role:
type: string
description: Message role
enum:
- system
- user
- assistant
- tool
content:
type: string
description: Message content
max_tokens:
type: integer
description: >-
Max output tokens. Reasoning counts against this too - give it
headroom (e.g. 2000+) when thinking is on
default: 500
thinking:
type: object
description: >-
Deep-thinking switch. ON by default; pass {"type": "disabled"} to
turn it off and cut latency and output tokens sharply
properties:
type:
type: string
enum:
- enabled
- disabled
default: disabled
reasoning_effort:
type: string
description: >-
Thinking depth tier (do not combine with thinking.disabled).
Measured: low ~226, high ~960 reasoning tokens
enum:
- low
- medium
- high
stream:
type: boolean
description: >-
Stream via SSE. Combine with stream_options.include_usage to get
usage in the final chunk
default: false
temperature:
type: number
description: Sampling temperature
response_format:
type: object
description: >-
Structured output. Supports {"type": "json_schema", "json_schema":
{name, strict, schema}}
tools:
type: array
description: Function-calling tool list, standard OpenAI format
items:
type: object
SeedChatResponse:
type: object
properties:
id:
type: string
description: Request ID
model:
type: string
choices:
type: array
description: >-
Completion results. Besides content, message carries
reasoning_content when thinking is on
items:
type: object
usage:
type: object
description: >-
Usage. completion_tokens_details.reasoning_tokens = thinking spend;
prompt_tokens_details.cached_tokens = implicit cache hits
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: API Key from the APIYI console
````