Kimi K3.1 Pro API Documentation

Kimi K3.1 Pro builds on Kimi K3 with improvements in coding, 3D-development workflows, and research. Use the exact model ID below with MixRoute Chat Completions.

Model Information

Field	Value
Model ID	`kimi-k3.1-pro`
API	`POST /v1/chat/completions`
Context window	1M tokens (provider specification)

Model capabilities and limits below follow the provider specification. Effective availability, request limits, and pricing depend on the MixRoute route and Model Marketplace.

Request Examples

Set MIXROUTE_API_KEY to your MixRoute API key. The examples select low reasoning effort.

cURL
Python
Streaming

curl "https://api.mixroute.ai/v1/chat/completions" \
  -H "Authorization: Bearer $MIXROUTE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kimi-k3.1-pro",
    "messages": [{"role": "user", "content": "Suggest three ways to simplify this application architecture."}],
    "reasoning_effort": "low"
  }'

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["MIXROUTE_API_KEY"],
    base_url="https://api.mixroute.ai/v1",
)
response = client.chat.completions.create(
    model="kimi-k3.1-pro",
    messages=[{"role": "user", "content": "Suggest three ways to simplify this application architecture."}],
    reasoning_effort="low",
)
print(response.choices[0].message.content)

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["MIXROUTE_API_KEY"],
    base_url="https://api.mixroute.ai/v1",
)
stream = client.chat.completions.create(
    model="kimi-k3.1-pro",
    messages=[{"role": "user", "content": "Suggest three ways to simplify this application architecture."}],
    reasoning_effort="low",
    stream=True,
)
for chunk in stream:
    if chunk.choices:
        print(chunk.choices[0].delta.content or "", end="", flush=True)

Request Fields

Parameter	Type	Required	Description
`model`	string	Yes	Use `kimi-k3.1-pro`.
`messages`	array	Yes	Messages containing `role` and `content`.
`reasoning_effort`	string	No	`low`, `high`, or `max`; default: `max`. Thinking is always enabled.
`max_completion_tokens`	integer	No	Output-token budget; provider default 131072, maximum 1048576, subject to context and route limits.
`stream`	boolean	No	Set `true` for SSE streaming.
`tools`	array	No	OpenAI-format function definitions.
`tool_choice`	string	No	`auto`, `none`, or `required`.

Usage Notes

Omit the fixed sampling settings: temperature=1.0, top_p=0.95, n=1, presence_penalty=0, and frequency_penalty=0. Do not pass the K2.x thinking parameter.
For follow-up turns and tool calls, preserve the complete assistant message, including reasoning_content and tool_calls; do not keep only content.
For image input, send content as an array with an image_url part containing a base64 data URL. The provider does not accept public image URLs. Upstream file IDs are not interchangeable with MixRoute files.
Streaming separates reasoning_content from final-answer content. The streaming example prints only the final answer.

Chat Completions request format

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Kimi K3.1 Pro

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Usage Notes