Grok model family (Grok 4 / 4.1 / 4.5)

Overview

xAI's frontier LLM line. Grok 4.5 (July 9, 2026), the first model co-developed with Cursor, is a mixture-of-experts system Musk describes as 'Opus-class, but faster, more token-efficient and lower cost,' aimed at coding, agents and knowledge work; Grok 4.1 Fast offers a 2M-token context window for agentic tool use.

Grok 4.5 launched publicly July 9, 2026 via the API, Grok Build and Cursor (EU availability delayed to mid-July); benchmarks are competitive but by xAI's own numbers 'just short of best-in-class.' The 6T-parameter Grok 5 is still training on Colossus 2.

Key Specs