Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's news post(opens in new tab).
Reasoning can be enabled/disabled using the reasoning enabled parameter in the API. Learn more in our docs(opens in new tab)
Modalities
Price
Free
Context
2M
Released
Sep 19, 2025
Knowledge Cutoff
Sep 2025
Token volume and request traffic to this model over time.
Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's news post. Reasoning can be enabled/disabled using the reasoning enabled parameter in the API. Learn more in our docs
Yes. The pricing shown on this page for Grok 4 Fast is zero, so you are not charged for prompt or completion tokens. Free endpoints are rate limited — see the rate limit docs.
Grok 4 Fast has a 2,000,000 token context window.
Grok 4 Fast accepts text, images and files such as PDFs as input and returns text.
Grok 4.6, Grok 4.5, Grok Build 0.1 and 3 more are other text models from SpaceXAI.
Grok 4 Fast was released on September 19, 2025. Its knowledge cutoff is September 30, 2025.