Grok 4.3 is an xAI model positioned as a unifying successor within the Grok family. In xAI's May 15, 2026 developer migration documentation, Grok 4.3 is explicitly named as the redirect target for several prior Grok endpoints that were retired on that date, including the Grok 4 fast reasoning and non-reasoning variants, grok-4-0709, grok-3, and related slugs. Reasoning-mode requests land on Grok 4.3 with low reasoning effort, while non-reasoning requests are served with reasoning disabled, making it the practical fallback for nearly the entire previous Grok lineup on the xAI API. This consolidating role signals a deliberate shift by xAI toward a single flagship reasoning model rather than a sprawling set of variants.
The model's fit is shaped by its benchmark placement and a sharp pricing reset. Reporting from Fello AI records Grok 4.3 scoring 53 on the Artificial Analysis Intelligence Index, placing it above Claude Sonnet 4.6 but below GPT-5.5, Claude Opus 4.7, and Gemini 3.1 Pro Preview, which frames it as a mid-frontier rather than top-tier option. The release followed an earlier $300-per-month SuperGrok Heavy beta, with broader API availability around April 30, 2026, and an input price roughly 40% lower than Grok 4.20 alongside an output price cut closer to 60%. Together, those moves position Grok 4.3 as a cost-conscious workhorse for developers who want Grok-style reasoning and tool use without paying premium-frontier rates.
