Grok 4 Fast Reasoning
grok-4-fast is X's latest advancement in cost-efficient reasoning models.
Input
Output
Context
2000K
Max Output
131K
Parameters
—
Technical Specifications
Model TypeChat
Context Window2.0M
Max Output Tokens131K
Parameters—
Training Cutoff—
Licenseproprietary
Capabilities
Input Modalities
textimage
Output Modalities
text
Features
chain_of_thoughtfunction_callingreasoningstructured_outputvision
Resources & Links
proprietary — Proprietary - API access only
Related Tools
Data sourced from official provider APIs and documentation
Last updated: May 5, 2026
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