Grok
Also known as: Grok AI
Grok launched in November 2023, initially available only to X Premium subscribers, as xAI's first public product. The model is named after a term from Robert Heinlein's Stranger in a Strange Land, meaning to understand something deeply and intuitively. From the start, Grok was designed with a distinctive personality: more willing to engage with edgy or politically charged topics, and with a built-in sense of humor that other frontier assistants deliberately avoid.
The model family has evolved rapidly. Grok 3 (February 2025) was trained on 10x more compute than Grok 2, using xAI's Colossus data center, and introduced Think mode for step-by-step reasoning. Grok 4 arrived in 2025 with native tool use and real-time search. As of late May 2026, Grok 4.3 is the recommended production model per xAI's own documentation, with Grok 4.20 Reasoning positioned as the extended-thinking variant. The current model family also includes image generation (via Aurora), video generation, and voice capabilities via the xAI API.
Grok's distinctive moat is real-time X integration: it can search X posts directly in response to queries, making it strong for social media monitoring, trend tracking, and questions about current events where the answer lives in the public X stream rather than static training data. For builders, xAI offers an OpenAI-compatible API that makes it straightforward to plug Grok into existing toolchains. The main tradeoffs versus Claude or GPT-5 are smaller ecosystem, fewer third-party integrations, and ongoing stability questions following a significant outage in April 2026.