Grok 4 Fast
Notable release: A meaningful new model: a new size or version, or a strong free-to-download model from a known lab.
Key facts
- Released
- Sep 19, 2025
- What it does
- Text and chat: Writes, answers questions and holds a conversation.Code: Writes, explains and fixes code.Thinks first: Can reason step by step before it answers: slower, but better at maths, code and tricky questions.
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- How
- For developers, through an API
- Announced as
- “Pushing the Frontier of Cost-Efficient Intelligence”
From trckr's archive of releases before it started watching. Date and details from Epoch AI's database of AI models (CC BY 4.0).
How it scores
From independent testers, never the lab's own claims.
Compare Grok 4 Fast with
It came out 22 days after Grok Code Fast 1, the lab's previous model.
The details
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