grok-4-fast-reasoning · Grok
Grok-4-fast is a cost-effective inference model developed by xAI that delivers cutting-edge performance with excellent token efficiency. The model features a 2 million token context window, advanced Web and X search capabilities, and a unified architecture supporting both "inference" and "non-inference" modes. Compared to Grok 4, it reduces thinking tokens by an average of 40% and lowers the price by 98% while achieving the same performance.
Grok-4-fast is a cost-effective inference model developed by xAI that delivers cutting-edge performance with excellent token efficiency. The model features a 2 million token context window, advanced Web and X search capabilities, and a unified architecture supporting both "inference" and "non-inference" modes. Compared to Grok 4, it reduces thinking tokens by an average of 40% and lowers the price by 98% while achieving the same performance.
Grok 4 Fast (reasoning) has a 2,000,000 token context window.
On AIHubMix, Grok 4 Fast (reasoning) costs $0.2 per million input tokens and $0.5 per million output tokens. Cached input reads are billed at $0.05 per million tokens.
Grok 4 Fast (reasoning) accepts text and image input.
Grok 4 Fast (reasoning) supports thinking, tool calling, function calling and structured outputs. Per-protocol parameter support is listed in the capability table on this page.
Grok 4 Fast (reasoning) is available through the AIHubMix unified API. The API is OpenAI-compatible: point your OpenAI SDK at https://aihubmix.com/v1, use your AIHubMix API key, and set the model name to grok-4-fast-reasoning — no other code changes needed.
Grok 4 Fast (reasoning) is developed by Grok. AIHubMix aggregates it alongside models from other providers behind one API and one bill.
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Use Grok 4 Fast (reasoning) via the AIHubMix unified API — one interface for every major LLM.