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Grok 4 Fast

xAIProprietaryPending Human Review

Grok 4 Fast is a proprietary xAI language-model release. A low-latency long-context model for information retrieval, tool use, and agent workflows. Reasoning and non-reasoning service variants share its underlying family. The API originally supported a two-million-token context. Later API retirement and alias migration to Grok 4.3 do not change the historical checkpoint identity. Weights are not publicly downloadable. Published agent and coding results depend on the evaluation harness, tool permissions, and inference settings, so no unsupported standalone benchmark score is assigned.

2025-09-19
Undisclosed
Proprietary

Specifications

Architecture
Undisclosed
License
Proprietary
Context Window
2,000,000 tokens
Type
multimodal
Modalities
textimage

Benchmark Scores

Advanced Specifications

Model Family
Grok
API Access
Available
Chat Interface
Not Available
Variants
ReasoningNon-reasoning

Capabilities & Limitations

Capabilities
reasoningtool uselong context
Known Limitations
Closed weightsAvailability and aliases can changeOutputs may hallucinate
Notable Use Cases
developer assistantsagent workflowsgeneral assistance
Tool Use Support
Yes

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