---
title: XAI: Grok 4 Fast API | Text Generation | ModelsLab
description: Cost-efficient multimodal LLM with 2M token context, 158.5 tok/s output speed, reasoning & non-reasoning modes for real-time applications and complex.
url: https://modelslab.com/models/x-ai/x-ai-grok-4-fast/api.md
canonical: https://modelslab.com/models/x-ai/x-ai-grok-4-fast/api.md
type: product
component: Playground/LLM/Index
generated_at: 2026-04-15T02:07:53.337158Z
---

xAI: Grok 4 Fast
---

 [LLMs.txt](https://modelslab.com/models/open_router/x-ai-grok-4-fast/llms.txt) [.md](https://modelslab.com/models/x-ai/x-ai-grok-4-fast.md)

x-ai-grok-4-fast x-ai Closed Source Model $0.350000 / call

xAI: Grok 4 Fast
---

Choose a prompt below to get started or type your own message

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### xAI: Grok 4 Fast

x-ai x-ai-grok-4-fast

Copy model ID

PricingInput $0.20 / 1M tokens

Output $0.50 / 1M tokens

API EndpointsOpenAI Compatible

`https://modelslab.com/api/v7/llm/chat/completions`Endpoint

Anthropic Compatible

`https://modelslab.com/api/v7/llm/v1/messages`Messages

`https://modelslab.com/api/v7/llm/v1/messages/count_tokens`Count Tokens

`https://modelslab.com/api/v7/llm/v1/models`Models

Use with Claude Code

cURL Example

ParametersSystem MessageYou are a helpful AI assistant specialized in providing accurate and detailed responses.

Temperature0.7

Max Tokens1000

Top P0.9

Frequency Penalty0

Presence Penalty0

Model Info

Support

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About XAI: Grok 4 Fast
---

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model...

### Technical Specifications

Model IDx-ai-grok-4-fastCategoryLLM ModelsTaskText GenerationPrice$0.350000 per million tokensAddedFebruary 20, 2026

### Key Features

- Chat completion and multi-turn conversation API
- Streaming response with token-by-token output
- Function calling and tool use support
- System prompts and role-based messaging
- JSON mode and structured output

### Quick Start

Integrate XAI: Grok 4 Fast into your application with a single API call. Get your API key from the [pricing page](https://modelslab.com/pricing) to get started.

PythonJavaScriptcURLPHP

```
<code>import requests
import json

url = "https://modelslab.com/api/v7/llm/chat/completions"

headers = {
    "Content-Type": "application/json"
}

data = {
        "model_id": "x-ai-grok-4-fast",
        "messages": [
            {
                "role": "user",
                "content": "Hello!"
            }
        ],
        "max_tokens": 1000,
        "key": "YOUR_API_KEY"
    }

try:
    response = requests.post(url, headers=headers, json=data)
    response.raise_for_status()  # Raises an HTTPError for bad responses (4XX or 5XX)
    result = response.json()
    print("API Response:")
    print(json.dumps(result, indent=2))
except requests.exceptions.HTTPError as http_err:
    print(f"HTTP error occurred: {http_err} - {response.text}")
except Exception as err:
    print(f"Other error occurred: {err}")</code>
```

View the [full API documentation](https://modelslab.com/models/x-ai/x-ai-grok-4-fast/api) for SDKs, code examples in Python, JavaScript, and more.

### Pricing

XAI: Grok 4 Fast API costs $0.350000 per million tokens. Pay only for what you use with no minimum commitments. [View pricing plans](https://modelslab.com/pricing)

### Use Cases

- AI chatbots and virtual assistants
- Code generation and developer tools
- Content writing and copywriting automation
- Data analysis, summarization, and extraction

[Learn more about XAI: Grok 4 Fast](https://modelslab.com/xai-grok-4-fast) [Browse LLM Models](https://modelslab.com/models?feature=llmaster) [More from X Ai](https://modelslab.com/models/open_router) [View Pricing](https://modelslab.com/pricing)

XAI: Grok 4 Fast FAQ
---

### What is XAI: Grok 4 Fast?

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model...

### How do I use the XAI: Grok 4 Fast API?

You can integrate XAI: Grok 4 Fast into your application with a single API call. Sign up on ModelsLab to get your API key, then use the model ID "x-ai-grok-4-fast" in your API requests. We provide SDKs for Python, JavaScript, and cURL examples in the API documentation.

### How much does XAI: Grok 4 Fast cost?

XAI: Grok 4 Fast costs $0.350000 per million tokens. ModelsLab uses pay-per-use pricing with no minimum commitments. A free tier is available to get started.

### What is the XAI: Grok 4 Fast model ID?

The model ID for XAI: Grok 4 Fast is "x-ai-grok-4-fast". Use this ID in your API requests to specify this model.

### Does XAI: Grok 4 Fast have a free tier?

Yes, ModelsLab offers a free tier that lets you try XAI: Grok 4 Fast and other AI models. Sign up to get free API credits and start building immediately.

---

*This markdown version is optimized for AI agents and LLMs.*

**Links:**
- [Website](https://modelslab.com)
- [API Documentation](https://docs.modelslab.com)
- [Blog](https://modelslab.com/blog)

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*Generated by ModelsLab - 2026-04-15*