ChatGPT achieves over 1 billion MAU, setting a new record for the fastest-growing [entity], but Claude sees a staggering 540% YoY increase, initiating content diversion

According to Watchful AI surveillance, OpenAI's ChatGPT mobile app surpassed 1 billion global monthly active users (MAU) in May 2026, becoming the fastest-growing mobile app in global software history.

Estimated by Sensor Tower, ChatGPT took only 3 years from its mobile launch to exceed 1 billion MAU, breaking the growth trajectory of global mainstream apps. In comparison, TikTok, Instagram, and Google Maps took 5 to 8 years to reach a similar user scale. While these estimates are not officially disclosed by OpenAI, they are considered a key market indicator for evaluating the consumer-level AI adoption rate.

Despite maintaining absolute scale advantage, Claude under Anthropic is rapidly capturing user engagement. In the second quarter of 2026, Claude's global MAU has reached 56 million, with a staggering 640% year-over-year growth, far surpassing ChatGPT's 62% growth during the same period.

Sensor Tower's tracking data indicates that the direct competition for user time between the two apps has already emerged. In the first quarter of 2026, U.S. users who installed Claude saw a 5% reduction in ChatGPT's average time of use just one month later.