OpenAI’s ChatGPT has crossed the milestone of 1 billion monthly active users, becoming the fastest app in history to reach the mark, according to a Reuters report citing estimates from market intelligence firm Sensor Tower. The achievement underscores the rapid adoption of generative AI technologies and cements ChatGPT’s position as the world’s leading consumer AI application.
According to Sensor Tower, ChatGPT reached 1 billion monthly active users in May 2026, roughly three years after its launch. The pace of growth surpassed that of major digital platforms including Google Maps, TikTok, Instagram, and YouTube, all of which took significantly longer to reach a similar user base.
The milestone comes at a time when competition in the artificial intelligence industry is intensifying. OpenAI and Anthropic are increasingly viewed as the two most influential players in the generative AI race, with both companies expanding their consumer and enterprise offerings. Reuters noted that Anthropic recently confidentially filed for a U.S. initial public offering, while OpenAI is reportedly preparing for its own IPO filing in the coming weeks.
While ChatGPT remains the dominant AI chatbot by user numbers, Sensor Tower’s data highlights the rapid growth of competitors. As of the second quarter of 2026, Anthropic’s Claude had an estimated 56 million monthly active users globally. The report also noted that Claude’s year-over-year monthly active user growth rate of approximately 640% significantly outpaced ChatGPT’s 62% growth, albeit from a much smaller base.
The data further suggests that competition is beginning to influence user behaviour. According to Sensor Tower, U.S. users who installed Claude during the first quarter of 2026 spent around 5% less time on ChatGPT one month after installation compared with their average usage over the previous eight months.
As generative AI adoption continues to accelerate globally, the race among AI companies is expected to intensify. With ChatGPT now surpassing 1 billion monthly active users, OpenAI has established a significant lead in consumer AI, but growing competition from rivals such as Claude suggests the battle for long-term market leadership is far from over.
