Grok 4 Fast

Grok 4 Fast is xAI's lightweight tier model in the Grok family, positioned for applications requiring fast response times rather than maximum reasoning capability. Created by xAI, it represents the speed-optimized variant of their fourth-generation language model architecture. The model supports both text and image inputs with an exceptionally large 2 million token context window, allowing it to process extensive documents or maintain long conversations while delivering outputs at 148.78 tokens per second. With a time to first token of 3.9 seconds, it provides rapid initial response generation suitable for interactive applications. However, it does not include tool calling capabilities, focusing instead on pure text and image understanding tasks. Grok 4 Fast is designed for workloads where processing speed and large context handling are more critical than advanced reasoning or agent capabilities. Its multimodal support and massive context window make it suitable for document analysis, content summarization, and conversational applications that need to maintain context over extended interactions.