Grok 4 Fast
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