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What Is Claude Sonnet 5? Features, Pricing & Performance
Grok 4 Fast
All the power of Grok 4, optimised for speed. Grok 4 Fast delivers intelligent, real-time responses for high-demand tasks without the wait.
- Gemini 3 Pro
- Claude
- GPT-5.6 Sol
- Grok 4.5
- DeepSeek V4
- 43M+Active Users
- 4.7/5 ⭐Rated on App Store & Google Play
- 500K+User Reviews
- 236Countries & Regions
Fast & Fearless, Grok 4 Fast
xAI's most efficient model — 2M token context, 40% fewer thinking tokens, 47x cheaper than Grok 4, and #1 on LMArena Search Arena
High Intelligence at the Lowest Cost in Its Class
Grok 4 Fast is xAI's cost-efficient reasoning model, released September 2025, built on the learnings from Grok 4 but optimized to deliver frontier-level intelligence at dramatically lower computational cost. Using approximately 40% fewer thinking tokens on average while matching Grok 4's performance on most tasks, it costs 47 times less to achieve equivalent results — making it one of the best value propositions in AI today. It became available to all users including the free tier on the day of release, demonstrating xAI's aim to make frontier-quality reasoning genuinely accessible. Available in Chat Smith.
Two Modes: Reason When You Need To, Speed When You Don't
Grok 4 Fast ships as two API endpoints — grok-4-fast-reasoning and grok-4-fast-non-reasoning — within a single unified architecture. In reasoning mode, the model activates extended step-by-step thinking for complex problems, delivering careful, accurate answers to technical questions, multi-step analysis, and coding challenges. In non-reasoning mode, it responds fast and directly for simple questions, conversation, and tasks where a quick, accurate answer matters more than thorough deliberation. Inside Chat Smith, this flexibility means you're always working with the right level of intelligence for each moment without switching between separate models.
The Largest Context Window in Its Price Range
Grok 4 Fast supports a 2 million token context window — the largest available in its price tier and more than twice the size of GPT-5's 400K context and double Gemini 2.5 Pro's 1M context. This massive context capacity lets you load entire codebases, large document collections, extended project histories, or very long research threads into a single session. For developers building applications that process large inputs, or professionals who need to work with extensive documentation, this context window is a significant practical advantage at a price point that makes production deployment genuinely viable.
Real-Time Web and X Search Carried Over From Grok 4
Like its predecessor, Grok 4 Fast integrates real-time web search and X (Twitter) search natively into its reasoning process. When you ask about current events, recent developments, live data, or anything time-sensitive, the model searches and synthesizes current information rather than relying only on its training. The X search capability — with keyword, semantic, and media search across posts, profiles, and threads — is one of xAI's most distinctive features and remains fully available in Grok 4 Fast, making it especially powerful for any task where up-to-the-minute information matters.
The Best Value for High-Volume AI Applications
At $0.20 per million input tokens and $0.50 per million output tokens, Grok 4 Fast is priced to make production-scale AI accessible. For developers building chatbots, research tools, document processing pipelines, or any application that sends large volumes of AI requests, the combination of Grok 4 Fast's quality, 2M context, tool use capabilities, and price creates a practical foundation for building real products at scale. It ranked number one on LMArena's Search Arena — beating OpenAI o3-search — confirming that the quality delivered at this price point is genuine, not a compromise.
Multiple Models, One Platform
Access leading AI models in one place, compare responses, and choose the best answer for every task.
Multiple Models
Access GPT, Claude, Gemini, DeepSeek, Grok, and more in one place.
Better Value
Get access to premium AI models without paying for multiple subscriptions.
Easy Comparison
Compare responses across different models to find the best answer for every task.
One Workspace
Chat, write, research, and create with your favorite AI models in a single app.
Just 3 Simple Steps
Chat with an advanced AI assistant to get answers, solve problems, generate content, and explore ideas in seconds.
Step 1
Enter a question, task, or topic you'd like help with, and provide any details or context that may be relevant.
Step 2
The AI analyzes your request and generates accurate, relevant, and context-aware responses in real time.
Step 3
Continue the conversation, refine your instructions, and explore new ideas through natural back-and-forth interactions.
Ask Us Anything
What is Grok 4 Fast on Chat Smith?
Chat Smith gives you access to xAI's Grok 4 Fast, a speed-optimized version of the powerful Grok 4 model. It delivers quick, intelligent responses for everyday tasks while retaining strong reasoning ability, making it the ideal choice when you want xAI-quality answers without waiting for the full-depth model to process.
How does Grok 4 Fast work inside Chat Smith?
Open Chat Smith, select Grok 4 Fast from the model picker, and start chatting. The model processes your prompt rapidly and streams the response in real time. No API keys or technical setup needed — you get fast, capable AI assistance through a clean chat interface with just a single tap.
What makes Grok 4 Fast different from Grok 4?
Grok 4 is the full-power reasoning model built for deep analysis. Grok 4 Fast is its speed-focused counterpart, optimized to deliver strong answers significantly faster. It retains much of Grok 4's intelligence but prioritizes response time, making it perfect for daily workflows where both quality and speed matter.
What can I use Grok 4 Fast for?
It handles everyday tasks efficiently including answering questions, writing and editing content, summarizing information, brainstorming ideas, translating text, explaining concepts, writing code, and assisting with research. Its fast response time keeps your momentum going without the wait of a heavier reasoning model.
Does Grok 4 Fast support image and multimodal input?
Yes. Through Chat Smith you can send images alongside text prompts. Grok 4 Fast can analyze photos, read text in images, interpret visual content, and answer questions that combine text and image understanding, delivering multimodal capability with the speed you need for productive conversations.
How accurate are responses from Grok 4 Fast?
Grok 4 Fast delivers strong accuracy for general knowledge, writing, coding, and everyday reasoning. It balances speed with reliability, handling most queries with confidence. For tasks requiring the deepest multi-step analysis, the full Grok 4 model may provide even more thorough results.
How can I get the best results from Grok 4 Fast?
Write clear, focused prompts that specify what you need. For straightforward tasks it excels with minimal instruction. For more complex queries, add context and break requests into steps. Grok 4 Fast responds best to direct, well-structured inputs where your intent is immediately clear.
When should I use Grok 4 Fast instead of Grok 4?
Choose Grok 4 Fast for everyday conversations, quick content drafting, code writing, brainstorming, and any task where a fast, reliable answer keeps you productive. Switch to the full Grok 4 when tackling deeply complex analysis, advanced mathematical proofs, or tasks where thoroughness outweighs speed.
Can I switch between Grok 4 Fast and other models?
Yes. Chat Smith lets you switch between AI models at any time, even mid-conversation. Use Grok 4 Fast for rapid-fire daily tasks and switch to Grok 4 or other models when a question demands deeper reasoning. This flexibility means you always have the right level of power for every task.
Is Grok 4 Fast on Chat Smith free to use?
You can start chatting with Grok 4 Fast for free with no software to install or complicated sign-up process. Chat Smith provides generous free access, while premium plans unlock higher message limits and additional AI models for users who rely on fast AI assistance throughout the day.
Is my data safe when using Grok 4 Fast?
Chat Smith is committed to user privacy. Your conversations are processed to generate responses and managed according to the app's privacy policy. Chat Smith does not sell personal data to third parties. Review the privacy policy in app settings for full details on how your information is handled.
Do I need technical knowledge to use Grok 4 Fast?
Not at all. Chat Smith is designed for everyone. Open the app, choose Grok 4 Fast, and type your question in plain language. No programming, API setup, or AI expertise required. Whether you are a student, professional, or curious explorer, fast and intelligent AI is just one tap away.
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