Grok 4.1 Fast Is Now Available in Puter.js

55 minutes ago 1

Reynaldi Chernando

November 20, 2025

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Puter.js now supports Grok 4.1 Fast, giving developers access to xAI's latest frontier model.

What is Grok 4.1 Fast?

Grok 4.1 Fast is xAI's best tool-calling model with a 2M context window. It reasons and completes agentic tasks accurately and rapidly, excelling at complex real-world use cases such as customer support and finance.

Key Capabilities

  1. Superior Tool Calling - Frontier-level agentic tool use trained across dozens of domains for real-world enterprise workflows

  2. Long Context Performance - Consistent performance across full 2M token context window through long-horizon reinforcement learning

  3. Advanced Search & Research - State-of-the-art real-time information retrieval with native X integration and web-browsing

  4. Improved Factuality - Hallucination rate cut in half compared to Grok 4 Fast while maintaining equivalent accuracy

  5. Agent Tools API Integration - Built-in server-side tools (web search, X search, code execution, MCP) managed entirely by xAI infrastructure

Examples

Text generation

puter.ai.chat("Explain neural networks simply", { model: 'x-ai/grok-4.1-fast' });

Tool calling

function getWeather(location) { const mockWeatherData = { 'Paris': '22°C, Partly Cloudy', 'London': '18°C, Rainy', 'New York': '25°C, Sunny', 'Tokyo': '28°C, Clear' }; return mockWeatherData[location] || '20°C, Unknown'; } const tools = [{ type: "function", function: { name: "get_weather", description: "Get current weather for a given location", parameters: { type: "object", properties: { location: { type: "string", description: "City name e.g. Paris, London" } }, required: ["location"] } } }]; // Make initial request with tools const userInput = "What's the weather in Paris?" const completion = await puter.ai.chat(userInput, { model: 'x-ai/grok-4.1-fast', tools, }); // Check if AI wants to call a function if (completion.message.tool_calls?.length > 0) { const toolCall = completion.message.tool_calls[0]; if (toolCall.function.name === 'get_weather') { // Parse arguments and call the function const args = JSON.parse(toolCall.function.arguments); const weatherData = getWeather(args.location); // Send result back to AI for final response const finalResponse = await puter.ai.chat([ { role: "user", content: userInput }, completion.message, { role: "tool", tool_call_id: toolCall.id, content: weatherData } ], { model: 'x-ai/grok-4.1-fast' }); console.log(finalResponse); } }

Complex reasoning

puter.ai.chat("Compare the benefits and drawbacks of solar vs wind energy", { model: 'x-ai/grok-4.1-fast' } );

Image analysis

puter.ai.chat( "What is in this image?", "https://assets.puter.site/doge.jpeg", { model: 'x-ai/grok-4.1-fast' } );

Get Started Now

Just add one script tag to your HTML:

<script src="https://js.puter.com/v2/"></script>

No API keys and no infrastructure setup. Start building with Grok 4.1 Fast immediately.

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