George Francis Hotz (born October 2, 1989), known online as geohot, is an American security hacker, entrepreneur, and software engineer. He gained prominence for developing iOS jailbreaks, reverse engineering the PlayStation 3, and facing a subsequent lawsuit from Sony. He founded comma.ai, a vehicle automation company, and later created tinygrad, a deep learning framework. As of 2025, he remains a notable figure in both security research and open-source artificial intelligence.
Hotz was born in 1989 and showed early aptitude for technology. He attended the Academy for Engineering and Design Technology at the Bergen County Academies, a magnet public high school in Hackensack, New Jersey, and was an alumnus of the Johns Hopkins Center for Talented Youth. He briefly attended the Rochester Institute of Technology and Carnegie Mellon University before pursuing independent research and hacking projects.
Security research
Hotz first attracted attention in August 2007 at age 17, when he became the first person reported to remove the SIM lock on an iPhone. He traded his second unlocked 8 GB iPhone to Terry Daidone, founder of CertiCell, for a Nissan 350Z and three 8 GB iPhones. In October 2009, he released blackra1n, a jailbreak compatible with all iPhone and iPod Touch devices running iOS 3.1.2. He announced the discontinuation of jailbreaking in July 2010, but continued to release techniques until October 2010, including limera1n, which was publicly disclosed that month.
Hotz shifted focus to the PlayStation 3 in December 2009. In January 2010, he announced he had gained read and write access to the system's memory and hypervisor-level access to the CPU, and released an exploit publicly on January 26, 2010. The release prompted Sony to announce a firmware update removing the OtherOS feature in March 2010. Hotz posted on Twitter in July 2010 that he had abandoned his PlayStation efforts, but later faced a lawsuit after the hacking group fail0verflow presented a flaw at the 27th Chaos Communication Congress in December 2010. Hotz posted the private key in January 2011, leading Sony to file for a temporary restraining order. The lawsuit settled in April 2011, with Hotz agreeing not to resume research on Sony products.
In June 2014, Hotz released towelroot, a one-click Android root exploit built around the CVE-2014-3153 vulnerability discovered by hacker Pinkie Pie. Originally targeting the Samsung Galaxy S5, the exploit was compatible with most Android devices at the time, including the Nexus 5 and Galaxy S4 Active. Samsung responded with a corrected software update.
Career and comma.ai
Hotz earned meaningful side income from public donations for his security research. He worked at Facebook from May 2011 to January 2012. In July 2014, Google hired him to work on the Project Zero team, where he developed QIRA, a tool for dynamic binary analysis. He was employed at the startup Vicarious from January to July 2015, and later he took a short internship at Twitter in late 2022.
In September 2015, Hotz founded comma.ai to develop advanced driver-assistance systems using machine learning. He demonstrated a self-driving Acura ILX that got a National cease-and-desist letter from the California Department of Motor Vehicles. The company initially planned to sell a device called the "comma one" but canceled it in October 2016 after the National Highway Traffic Safety Administration filed questions. A month later, the firm released openpilot as open-source software.
comma.ai subsequently developed hardware devices including the comma two (2020) and comma three (2021). In November 2020, Consumer Reports ranked openpilot above all other assistances, including Tesla Autopilot and Super Cruise, for driver engagement and ease of use. As of 2025, the system supported over 300 vehicle models, with users logged over 100 million miles driven. Hotz stepped down from day-to-day leadership in October 2022, remaining on the board.
tiny corp and tinygrad
In November 2022, Hotz founded tiny corp, where he focuses on developing tinygrad, an open-source deep learning framework. The project can be used for inference and training of neural networks and has been used for machine-learning applications, including an implementation for running large language models on a variety of hardware. He has publicly discussed the goal of simplifying the complexity of machine learning and making it accessible to a broader range of users.
His approach to deep learning emphasizes minimal code and flexibility, supporting both research and production use cases. While not linked to as much media attention as his previous work, tiny corp has cultivated a community of developers. Hotz has also continued to participate in Machine learning discussions and often shares his ideas on social media about the future of Artificial intelligence and self-driving systems.
Public persona and impact
Throughout his career, Hotz has been a controversial and influential figure in both the hacking and Machine learning communities. His early jailbreaks opened the door to the iOS modding ecosystem, and his PlayStation 3 work highlighted platform security issues. His move into autonomous driving with comma.ai helped popularize the idea of machine-learning based advanced driver assistance used with photos. Neural-network, or both, applied to autonomous vehicle control.
His social media presence, often under the handle geohot, has made him a visible commentator on topics ranging from security to the state of AI. In 2022, he announced a internship at Twitter after Elon Musk's acquisition, but resigned in five weeks. Later, he launched tiny . He continues to be a regular contributor to open-source and its project tinygrad, contributing to the field of Deep learning frameworks, pushing forward the notion that understanding and optimizing low-level code is key to making AI accessible.