Grok 4.3: xAI’s Latest AI Model With a 1‑Million‑Token Context Window

xAI’s documentation also describes Grok 4.3 as the “most intelligent and fastest model” in the company’s lineup at the time of publication .

When Was Grok 4.3 Released?

Release notes indicate that Grok 4.3 became available through the xAI API around May 1, 2026 .

The model is positioned as xAI’s latest reasoning-focused system, intended for demanding tasks such as scientific analysis, complex coding work, and advanced research workflows .

Technology news coverage from the same period also highlighted the launch, noting the model’s large context window and improved processing speed as major updates .

Transition From Earlier Grok Models

The introduction of Grok 4.3 coincided with changes to xAI’s model lineup. Migration documentation shows that the company began retiring several older models to concentrate development on newer systems .

Examples of models scheduled for retirement include:

• grok-3
• grok-4-fast-reasoning
• grok-4-fast-non-reasoning
• grok-code-fast-1

For developers using the xAI API, moving to Grok 4.3 is part of the broader transition toward the next generation of Grok models within the ecosystem .

What Is Grok 4.3 Best For?

Based on official documentation and release notes, the model is designed for tasks such as:

• Multi‑step reasoning and analytical problem solving
• Scientific or technical data analysis
• Software development and code generation
• AI agents that must call external tools or APIs

Thanks to its 1‑million‑token context window, Grok 4.3 can work with extremely long documents, large codebases, or complex datasets more effectively than many earlier models .

The Bottom Line

As of the latest available developer documentation in 2026, Grok 4.3 is identified as the newest Grok model available through the xAI API, offering improved reasoning capabilities and a massive 1‑million‑token context window .

Like most AI platforms, xAI continues to update its models frequently, so the latest version may change as new releases are announced.