Grok 4.20

• 🆕 xAI multimodal reasoning model, released March 2026.
• 📏 2-million-token context window for very long inputs.
• 🧠 Operates as a reasoning model that thinks before responding.
• 🔧 Agentic tool calling plus structured outputs supported.
• 👁️ Accepts text and image inputs, returns text.
• 🌐 Web search and function calling among native capabilities.
• ⚡ Tuned for fast responses in agentic, tool-calling workflows.
• 🏢 Developed by xAI.

xAI

xAI is an American artificial intelligence company and wholly owned subsidiary of SpaceX. The company develops AI systems under the Grok brand, spanning language models, image generation, and video synthesis. xAI has quickly established itself as a multimodal…

Grok 4.20 is xAI's multimodal reasoning model, released in March 2026, built around agentic tool use and a 2-million-token context window. According to xAI's documentation, it operates as a reasoning model that "thinks before responding" for complex tasks, with web search and function calling among its native capabilities. The large context window is intended to support very long inputs and multi-step, tool-driven workflows rather than one-shot prompting.

The model accepts text and image inputs and returns text. Function calling and structured outputs are available through the API, letting developers connect Grok to external tools and request organized response formats. xAI's own docs describe Grok 4.20 as offering fast responses with agentic tool calling and strict prompt adherence.

Within the same family, xAI also offers Grok 4.20 Multi-Agent, a companion deployment released the same day. The lineage continued with the later Grok 4.3, released in April 2026, which extends the same generational line of reasoning models.

Grok 4.20 is offered through xAI's API on an on-demand, pay-per-token basis. As with other Grok models, image inputs are converted into tokens that count toward the shared context budget alongside text, keeping the full window available for combined multimodal prompts.