Grok 4 Fast
xAI
Timeline
- · Released · evidence link
- · Evidence links · xAI · official articles
Excerpt
Grok 4 Fast is available now for all users
- · Catalogue listing · GitHub · xai-org/grok-build · code
Excerpt
response_started("msg_a", Some("grok-4"), 5))); out.extend(r.reduce(StreamEvent::AgentMessage("from A".into()))); out.extend(r.reduce(response_completed("msg_a", "end_turn"))); out.extend(r.reduce(response_started("msg_b", Some("grok-4-fast"), 6))); out.extend(r.reduce(StreamEvent::AgentMessage("from B".into()))); out.extend(r.reduce(response_completed("msg_b", "end_turn"))); out.extend(r.finish(&end_turn())); let frames: Vec<&Value> = out .iter() .filter(|m| msg_type(m) == Some("assistant")) .collect(); let [a, b] = frames.as_slice() else { panic!("one frame per response: {out:?}"); }; assert_eq!(json_str(a, "/message/id"), Some("msg_a")); assert_eq!(json_str(a, "/message/model"), Some("grok-4")); assert_eq!(json_str(b, "/message/id"), Some("msg_b")); assert_eq!(json_str(b, "/message/model"), Som
This code reference does not establish a working model identifier.
Signals 1
Specifications
Grok 4 Fast is a model from xAI, released on 19 Sep 2025.
Questions
When was Grok 4 Fast released?
On 19 Sep 2025.