xAI: Grok 4.1 Fast

x-ai/grok-4.1-fast

2000KContext Window

30KMax Output

Supported Protocols:reasoninginclude_reasoningmax_tokenstemperaturetop_pseedlogprobstop_logprobsresponse_formattoolstool_choicestructured_outputs

Online

Grok 4.1 Fast is xAI's best agentic tool calling model that shines in real-world use cases like customer support and deep research. 2M context window. Reasoning can be enabled/disabled using the `reasoning` `enabled` parameter in the API. [Learn more in our docs](

Capabilities

👁 Vision🧠 Reasoning🔧 Function CallingText GenerationCode GenerationAnalysis & Reasoningmodels.reasoning

Technical Specs

Input Modality

Text、Image、Text

Output Modality

Text

Arch

—

Default Temperature

0.7

Default Top_P

0.95

Pricing

Pay per use, no monthly fees

Input Token< ¥0.001/1K Token

Output Token< ¥0.001/1K Token

Quick Start

from openai import OpenAI

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

response = client.chat.completions.create(
    model="x-ai/grok-4.1-fast",
    messages=[
        {"role": "user", "content": "Hello!"}
    ],
)

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