x-ai/grok-4-1-fast
Model Card
Grok 4.1 Fast is xAI's best tool-calling model released November 2025, featuring a 2M context window and halved hallucination rates versus Grok 4 Fast. It comes in reasoning and non-reasoning modes and is optimized for agentic workflows with native support for web search, X search, and code execution.
Context Window N/A
tokens
Max Output 2M
tokens
Input Cost $0.2
per million tokens
Output Cost $0.5
per million tokens
Input text, image
modalities
Tool Use Yes
Knowledge Cutoff Jul 2025
Release Date Nov 19, 2025
API Usage Example
Add Grok 4.1 Fast to your app with just a few lines of code.
No backend, no configuration required.
// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';
puter.ai.chat("Explain quantum computing in simple terms", {
model: "x-ai/grok-4-1-fast"
}).then(response => {
document.body.innerHTML = response.message.content;
});
<html>
<body>
<script src="https://js.puter.com/v2/"></script>
<script>
puter.ai.chat("Explain quantum computing in simple terms", {
model: "x-ai/grok-4-1-fast"
}).then(response => {
document.body.innerHTML = response.message.content;
});
</script>
</body>
</html>
# pip install openai
from openai import OpenAI
client = OpenAI(
base_url="https://api.puter.com/puterai/openai/v1/",
api_key="YOUR_PUTER_AUTH_TOKEN",
)
response = client.chat.completions.create(
model="x-ai/grok-4-1-fast",
messages=[
{"role": "user", "content": "Explain quantum computing in simple terms"}
],
)
print(response.choices[0].message.content)
curl https://api.puter.com/puterai/openai/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_PUTER_AUTH_TOKEN" \
-d '{
"model": "x-ai/grok-4-1-fast",
"messages": [
{"role": "user", "content": "Explain quantum computing in simple terms"}
]
}'
More AI Models From xAI
Grok 4.20 Beta
Grok 4.20 Beta is xAI's newest flagship model, featuring a native 4-agent collaboration system (Grok, Harper, Benjamin, Lucas) that reasons in parallel and debates internally before delivering a unified response. It introduces a rapid-learning architecture that improves weekly from real-world feedback, and builds on a ~3T parameter MoE backbone with up to 2M token context. It claims a 65% reduction in hallucinations over Grok 4.1 and strong gains in coding, math, and engineering reasoning.
ChatGrok 4.20 Multi-Agent Beta
Grok 4.20 Multi-Agent Beta is an API-specific variant of Grok 4.20 optimized for orchestrating multiple agents that collaborate on deep research tasks. It supports web search and X search tools natively, uses the same 2M token context window, and is designed for developer workflows requiring structured multi-agent collaboration.
ChatGrok 4.1 Fast Non-Reasoning
Grok 4.1 Fast Non-Reasoning is the low-latency, non-reasoning variant of Grok 4.1 Fast that skips extended chain-of-thought for speed-critical applications. It shares the same model weights and 2M context window as Grok 4.1 Fast but delivers instant responses without deliberation overhead, ideal for real-time customer support and streaming interactions.
Frequently Asked Questions
You can access Grok 4.1 Fast by xAI through Puter.js AI API. Include the library in your web app or Node.js project and start making calls with just a few lines of JavaScript — no backend and no configuration required. You can also use it with Python or cURL via Puter's OpenAI-compatible API.
Yes, it is free if you're using it through Puter.js. With the User-Pays Model, you can add Grok 4.1 Fast to your app at no cost — your users pay for their own AI usage directly, making it completely free for you as a developer.
| Price per 1M tokens | |
|---|---|
| Input | $0.2 |
| Output | $0.5 |
Grok 4.1 Fast was created by xAI and released on Nov 19, 2025.
Grok 4.1 Fast can generate up to 2M tokens in a single response.
Grok 4.1 Fast has a knowledge cutoff date of Jul 2025. This means the model was trained on data available up to that date.
Grok 4.1 Fast accepts the following input types: text, image. It produces: text.
Yes, Grok 4.1 Fast supports tool use (function calling), allowing it to interact with external tools, APIs, and data sources as part of its response flow.
Yes — the Grok 4.1 Fast API works with any JavaScript framework, Node.js, or plain HTML through Puter.js. Just include the library and start building. See the documentation for more details.
Get started with Puter.js
Add Grok 4.1 Fast to your app without worrying about API keys or setup.
Read the Docs View Tutorials