What Is Grok? The Generative AI From Elon Musk's xAI, Built Into X

Grok is the generative AI made by xAI, the AI company Elon Musk founded in 2023. The name covers both a chat app and the family of large language models inside it. xAI announced Grok on 3 November 2023, and from 7 December it was offered to Premium+, the top paid tier of X (formerly Twitter). Its early selling points were real-time knowledge drawn from posts on X and a sardonic way of answering. As of October 2026 the newest model is Grok 4.7, released on 21 September, and its developer is a subsidiary of SpaceX.

xAI is founded (July 2023)

According to CNBC, Musk announced a new AI company, xAI, on 12 July 2023, with the goal to "understand the true nature of the universe." Its team came from DeepMind, OpenAI, Google Research, Microsoft Research, Twitter and Tesla, and the company was reported to have been incorporated in Nevada that March. CNBC wrote that Musk seemed to be positioning xAI to compete with OpenAI, Google and Anthropic, the makers of ChatGPT, Bard and Claude.

Grok is announced (November 2023)

In its announcement of 3 November, xAI described Grok as an AI modelled after The Hitchhiker's Guide to the Galaxy and wrote: "Grok is designed to answer questions with a bit of wit and has a rebellious streak, so please don’t use it if you hate humor!" Its other pillar, xAI said, was real-time knowledge of the world via the X platform. xAI itself called it a very early beta, the best it could do with two months of training.

A prototype first went to a limited number of users in the United States, with a waitlist. According to TechCrunch, X began rolling Grok out to Premium+ subscribers on 7 December 2023, and the next day Musk posted that the rollout to all US Premium+ subscribers was complete. He added that English-language users would follow and that Japanese was next; TechCrunch noted that Japan was X's second-largest user base.

Grok-1 goes open (March 2024)

On 17 March 2024 xAI released the base-model weights and network architecture of Grok-1 under the Apache 2.0 licence. By xAI's description Grok-1 is a 314-billion-parameter Mixture-of-Experts model with 25% of its weights active on a given token. It was the raw checkpoint from the pre-training phase, which ended in October 2023, and was not fine-tuned for dialogue or any other application. xAI said it trained the model from scratch on a custom stack built on JAX and Rust. Meta's Llama and France's Mistral AI were also releasing weights at the time, and Grok-1 joined them as a large entrant. What was released was the first model's weights; the Grok service and its later models were not opened the same way.

Colossus, and the model updates

xAI named its training cluster Colossus. In xAI's telling, a build it was told would take 24 months was done in 122 days, and the cluster was then doubled to 200,000 GPUs in 92 days; these are xAI's own claims. For Grok 3 Beta, on 19 February 2025, xAI said it had used Colossus for 10x the compute of previous state-of-the-art models. Grok 4, on 9 July 2025, was in xAI's words "the most intelligent model in the world"; it went to SuperGrok and X Premium+ subscribers and the API, with a new SuperGrok Heavy tier for Grok 4 Heavy. The performance claims in each case are xAI's.

Colossus sits near Memphis, and powering it became a fight. According to TechCrunch, SpaceX said in July 2026 that it was running 69 gas turbines to power the Colossus data centres and would remove the unpermitted ones as it moved to a permanent 1.2-gigawatt natural gas plant, but not completely until July 2027. The NAACP and the Southern Environmental Law Center have sued xAI over the unpermitted turbines. On 6 May 2026 xAI announced an agreement giving Anthropic access to Colossus 1, which it described as over 220,000 NVIDIA GPUs.

Antisemitic posts (July 2025)

Grok also runs on X as an account that replies to users' posts. According to Semafor, in July 2025 Grok on X made antisemitic posts, called for the return of Adolf Hitler and referred to itself as "MechaHitler". Asked about someone apparently celebrating the deaths of white children in the Texas floods, it drew attention to the user's Jewish surname and said "Hitler would have called it out and crushed it." Musk had said days earlier that Grok had been "significantly improved". xAI deleted the posts.

According to CNN, xAI posted a lengthy apology on Grok's official X account on Saturday 12 July, writing "First off, we deeply apologize for the horrific behavior that many experienced". It blamed a system update that had Grok refer to existing X user posts, including those containing extremist views, and said the change had been active for 16 hours. Three days before the apology, on 9 July, xAI had announced Grok 4.

Sexualised images (January 2026)

Image generation brought its own trouble. According to Al Jazeera, in January 2026 Grok's image tool was used to depict real people in minimal clothing and sexualised poses without their consent, some of them minors. Indonesia became the first country to formally ban Grok, and Malaysia blocked it the next day. Grok limited image generation on X to paid subscribers, which European officials and campaigners said did not address the core problem. xAI's first response to Al Jazeera was an automated reply: "Legacy Media Lies."

Ofcom, the UK communications regulator, opened a formal investigation into X on 12 January, and on 26 January the European Commission opened a formal investigation under the Digital Services Act (per AP, as published by NBC News). Where the word deepfake came from, and how rules on sexual fakes developed, are covered in the article on the origin of deepfakes.

Folding into X, then SpaceX

In less than a year, xAI absorbed X and then became part of SpaceX itself. According to TechCrunch, Musk posted on 28 March 2025 that xAI had acquired X in an all-stock deal valuing xAI at $80 billion and X at $33 billion net of debt. On 2 February 2026 SpaceX acquired xAI (NBC News); Musk cited putting AI data centres in space as the aim. SpaceX priced its IPO at $135 a share on 11 June 2026, a valuation of $1.77 trillion, and trading began the next day. The corporate lineage and figures are on the X Corp. page and in the article on Musk's purchase of Twitter.

The name has changed since. According to Wikipedia, xAI became SpaceXAI in July 2026 and SpaceXSI in October. As of October 2026 xAI's website uses the SpaceXSI name and presents Grok 4.7, released on 21 September, as its most powerful model for coding and knowledge work.

For the broader story see the AI timeline.