Summary ChatGPT surpassed 1 billion monthly active app users in May, becoming the fastest app to reach the milestone. Rival Claude grew faster year-over-year but remains far smaller.
(Reuters) - OpenAI's ChatGPT has crossed 1 billion global monthly active app users, becoming the fastest app ever to reach the milestone, according to estimates from market intelligence firm Sensor Tower.
The record comes amid growing competition between Anthropic and OpenAI for dominance in the rapidly expanding artificial intelligence market.
ChatGPT reached 1 billion MAUs in May, roughly three years after launch, surpassing the pace set by apps including Google Maps, TikTok, Instagram and YouTube, Sensor Tower said.
The firm said U.S. ChatGPT users who installed Anthropic's Claude app in the first quarter of 2026 spent 5% less time on ChatGPT one month after installation, compared with their average usage in the prior eight months.
Anthropic confidentially filed for a U.S. initial public offering on Monday, while Reuters has reported that OpenAI is also preparing to file for an IPO in the coming weeks.
As of the second quarter to date, Claude had 56 million global monthly active app users, while its year-over-year MAU growth of about 640% significantly outpaced ChatGPT's 62% growth, according to Sensor Tower.
