No application has climbed to 1 billion monthly active users as quickly as ChatGPT, which crossed that line in May after roughly three years on the market, according to estimates from market intelligence firm Sensor Tower. The achievement places OpenAI’s chatbot ahead of a generation of products that defined consumer software, with Google Maps, TikTok, Instagram and YouTube all taking longer to reach the same count.
The figure underscores how quickly AI assistants have shifted from curiosity to routine. Sensor Tower’s tally measures app users specifically, a benchmark that lets OpenAI’s pace be compared directly against earlier breakout platforms.
Rival Anthropic, though operating at a fraction of that scale, is expanding far faster in percentage terms. Its Claude app stood at 56 million monthly active users in the second quarter to date, while posting year-over-year growth of about 640% — well beyond the roughly 62% ChatGPT recorded over the same window.
There are early signs the competition is registering with users. Sensor Tower found that Americans who installed Claude in the first quarter of 2026 spent 5% less time on ChatGPT in the following month, compared with their average over the prior eight months.
Both companies are positioning for public markets. Anthropic lodged a confidential filing for a U.S. initial public offering on Monday, and Reuters has reported that OpenAI plans to file for its own IPO in the weeks ahead.
