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Available now on ModelsLab · Language Model

XAI: Grok 4 FastSpeed meets intelligence

Try XAI: Grok 4 FastAPI Documentation

Deploy Reasoning at Production Scale

Lightning-Fast Generation

10x Faster Response Times

Delivers responses in 2.55s to first token with 342.3 tokens per second output speed.

Massive Context Window

2 Million Token Context

Process entire documents and datasets without losing precision or reasoning quality.

Cost Efficiency

98% Lower Operational Cost

Uses 40% fewer thinking tokens while maintaining near-flagship performance on benchmarks.

Examples

See what XAI: Grok 4 Fast can create

Copy any prompt below and try it yourself in the playground.

Financial Analysis

“Analyze this quarterly earnings report and identify key financial trends, risk factors, and growth opportunities. Provide structured insights with supporting data points.”

Code Review

“Review this Python function for performance bottlenecks, security vulnerabilities, and code quality improvements. Suggest optimized alternatives.”

Research Synthesis

“Summarize these 50-page research papers on machine learning optimization and extract the most impactful findings and methodologies.”

Legal Document Analysis

“Extract key clauses, obligations, and risk areas from this contract. Flag potential issues and suggest clarifications.”

For Developers

A few lines of code.
Reasoning. Instant. Affordable.

ModelsLab handles the infrastructure: fast inference, auto-scaling, and a developer-friendly API. No GPU management needed.

  • Serverless: scales to zero, scales to millions
  • Pay per token, no minimums
  • Python and JavaScript SDKs, plus REST API
API Documentation 
import requests


response = requests.post(
    "https://modelslab.com/api/v7/llm/chat/completions",
    json={
  "key": "YOUR_API_KEY",
  "prompt": "",
  "model_id": ""
}
)
print(response.json())

FAQ

Common questions about XAI: Grok 4 Fast

Read the docs

Grok 4 Fast is an optimized version of Grok 4 designed for production workloads, delivering 10x faster responses while using 40% fewer thinking tokens. It maintains near-flagship accuracy on benchmarks like AIME 2025 (92%) and HMMT 2025 (93.3%) at 98% lower cost.

Grok 4 Fast supports a 2 million token context window, enabling it to process entire documents, datasets, and chat histories without losing precision or reasoning quality.

Grok 4 Fast costs $0.2 per 1M input tokens and $0.5 per 1M output tokens for both reasoning and non-reasoning modes, representing up to 98% cost reduction compared to Grok 4.

Grok 4 Fast includes multimodal support (text and images), function calling, structured outputs, cached input tokens, domain expertise in finance/healthcare/law/science, and multilingual fluency across dozens of languages.

Grok 4 Fast ranks number one on LMArena's Search Arena, beats GPT-5 mini on multiple benchmarks, and scores 85.7% on GPQA Diamond, 92% on AIME 2025, and 93.3% on HMMT 2025 while using significantly fewer tokens.

Ready to create?

Start generating with XAI: Grok 4 Fast on ModelsLab.

Try XAI: Grok 4 FastAPI Documentation