Grok-1.5
xAI's transitional model that added long-context reasoning ahead of Grok 2
Grok-1.5 is xAI’s follow-up to Grok-1, announced on March 29, 2024 as a step toward better reasoning and much longer context handling. Where Grok-1 topped out at 8,192 tokens, Grok-1.5 extended the context window to 128,000 tokens, letting it work through long documents and codebases in a single pass, and xAI reported gains on coding and math benchmarks compared to its predecessor. xAI did not disclose the parameter count or full architecture details for Grok-1.5, and the model was rolled out gradually to X users rather than through a public API. It served mainly as a bridge release: within months xAI had folded its improvements into Grok-2, and Grok-1.5 itself was never open-weighted the way Grok-1 was.