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X-Ai/Grok-4-Fast-Non-Reasoning

xAI · Released Dec 18, 2025 · Closed weights

Fast Grok model for responsive chat, reasoning, and tool-assisted work

Context window
2M
tokens in · 2M out
Open in the timeline
BENCHMARKS

Not in the Epoch Capabilities Index. Epoch benchmarks what it can run, so this is a gap in coverage, not a poor result.

xAI's past year

19 release days in the past year, about one every 19 days. The next is expected around Nov 7, 2026. Forecasts ↗

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Specifications

RELEASE DATEDec 18, 2025
WEIGHTSClosed weights
CONTEXT WINDOW2M
MAX OUTPUT2M
REASONINGNot listed
TOOL CALLINGNot listed
INPUTStext, image/jpeg, image/png, audio, video
OUTPUTStext

Models.dev record ↗

Specifications and prices from Models.dev; availability and limits may differ by provider. Benchmarks from Epoch AI (CC BY 4.0), LiveBench and the other sources named above.