Grok 4.1 Fast Reasoning

Grok 4.1 Fast Reasoning is a reasoning model for complex problem solving from xAI. Call grok-4-1-fast-reasoning through MixRoute using the endpoint shown below.

Key capabilities

OpenAI-compatible - Works with the OpenAI SDK by changing base_url
Streaming - Real-time token output through SSE
Multi-turn conversations - Uses role-based messages

Quick example

cURL
Python
Streaming

curl "https://api.mixroute.ai/v1/chat/completions" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "grok-4-1-fast-reasoning",
  "messages": [
    {
      "role": "user",
      "content": "Explain quantum entanglement in simple terms."
    }
  ],
  "max_tokens": 256
}'

from openai import OpenAI

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

response = client.chat.completions.create(
    model="grok-4-1-fast-reasoning",
    messages=[{"role": "user", "content": "Explain quantum entanglement in simple terms."}],
    max_tokens=256,
)

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

from openai import OpenAI

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

stream = client.chat.completions.create(
    model="grok-4-1-fast-reasoning",
    messages=[{"role": "user", "content": "Write a short poem about the sea."}],
    max_tokens=256,
    stream=True,
)

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

Parameters

Parameter	Type	Required	Description
`model`	string	Yes	Must be `grok-4-1-fast-reasoning`.
`messages`	array	Yes	Conversation messages with role and content.
`max_tokens`	integer	No	Maximum generated tokens.
`stream`	boolean	No	Enable SSE streaming. Default: false.
`temperature`	number	No	Sampling temperature when supported by the model.
`top_p`	number	No	Nucleus sampling threshold when supported.
`stop`	string \| array	No	Sequences that stop generation.
`tools`	array	No	OpenAI-compatible tool definitions.

Home

Model Introduction

Grok 4.1 Fast Reasoning

Key capabilities

Quick example

Parameters

​Key capabilities

​Quick example

​Parameters

Key capabilities

Quick example

Parameters