ChatGPT reaches 1 billion monthly active users, data shows

OpenAI’s ChatGPT has reached one billion global monthly active users, making it the fastest app to cross that threshold, according to estimates from market intelligence firm Sensor Tower.

The milestone, passed in May roughly three years after launch, means the chatbot outpaced the early growth of apps including Google Maps, TikTok, Instagram, and YouTube, states Sensor Tower.

The record arrives amid an intensifying contest between OpenAI and rival Anthropic. Sensor Tower data shows that US-based ChatGPT users who installed Anthropic’s Claude app during the first quarter of 2026 spent 5% less time on ChatGPT one month later, measured against their average usage over the prior eight months. That suggests Claude is starting to capture some attention, even though ChatGPT’s user base remains vastly larger.

Claude had 56 million monthly active users globally in the second quarter to date, a fraction of ChatGPT’s reach. But its year-over-year growth of roughly 640% far exceeded the 62% growth posted by ChatGPT.

Both companies are racing to cement their commercial positions: Anthropic confidentially filed for a US initial public offering on Monday, and Reuters has reported that OpenAI is also preparing to file for an IPO in the coming weeks.