Grok 3 Fast
A high-speed variant of xAI's Grok 3, optimized for rapid responses while retaining strong language understanding and tool-use capabilities.
X.ai High-speed text generation with tool-use support
Grok 3 Fast is a performance-optimized variant of xAI's Grok 3 model, released in April 2025 as part of the Grok 3 family. It is designed to deliver faster response times compared to the standard Grok 3 Beta while retaining the same core language understanding, function calling, and web search capabilities. The model supports a 131,072-token context window, making it capable of handling long documents and extended multi-turn conversations.
Grok 3 Fast is best suited for applications where response latency matters, such as real-time chat interfaces, high-throughput processing pipelines, and interactive AI assistants. Its support for function calling allows developers to integrate external tools and APIs, enabling agentic workflows that can act on live information. The model exposes an OpenAI-compatible API, which simplifies adoption for developers already working within that ecosystem.
What Grok 3 Fast supports
Fast Response Generation
Optimized for lower latency text generation, making it suitable for real-time interfaces and high-throughput pipelines where response speed is a priority.
Long Context Window
Supports a 131,072-token context window, allowing the model to process long documents, extended conversations, and complex multi-step inputs in a single request.
Function Calling
Enables structured integration with external tools and APIs, supporting the construction of agentic workflows where the model can invoke functions based on user input.
Web Search
Can retrieve up-to-date information from the web in real time, allowing responses to reflect current events and live data beyond the model's training cutoff.
OpenAI-Compatible API
Exposes an API interface compatible with the OpenAI SDK, allowing developers to integrate Grok 3 Fast without significant changes to existing code.
Text Generation
Generates coherent, contextually relevant text across a wide range of tasks including summarization, drafting, question answering, and instruction following.
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Get Started FreeBenchmark scores
Scores represent accuracy — the percentage of questions answered correctly on each test.
| Benchmark | What it tests | Score |
|---|---|---|
| MMLU-Pro | Expert knowledge across 14 academic disciplines | 79.9% |
| GPQA Diamond | PhD-level science questions (biology, physics, chemistry) | 69.3% |
| MATH-500 | Undergraduate and competition-level math problems | 87.0% |
| AIME 2024 | American math olympiad problems | 33.0% |
| LiveCodeBench | Real-world coding tasks from recent competitions | 42.5% |
| HLE | Questions that challenge frontier models across many domains | 5.1% |
| SciCode | Scientific research coding and numerical methods | 36.8% |
Common questions about Grok 3 Fast
What is the context window size for Grok 3 Fast?
Grok 3 Fast supports a context window of 131,072 tokens, which allows it to handle long documents, extended conversations, and complex multi-step tasks within a single request.
How does Grok 3 Fast differ from standard Grok 3 Beta?
Grok 3 Fast is optimized for faster response times compared to the standard Grok 3 Beta. It retains the same core capabilities including function calling, web search, and the 131K token context window, but is tuned for lower latency use cases.
What is the knowledge cutoff for Grok 3 Fast?
Based on the available metadata, Grok 3 Fast was released in April 2025. The exact training data cutoff date is not specified in the provided metadata; refer to xAI's official documentation for the most accurate information.
Does Grok 3 Fast support function calling and tool use?
Yes, Grok 3 Fast supports function calling, enabling integration with external tools and APIs. This makes it suitable for building agentic systems and workflows that need to interact with live data or external services.
Where can I find pricing information for Grok 3 Fast?
Pricing details for Grok 3 Fast are available on xAI's Models & Pricing Reference page at docs.x.ai/developers/models. MindStudio does not require you to manage API keys directly.
Parameters & options
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