Claude’s monthly active users rose 1,260 percent year over year in the third quarter of 2026, according to Sensor Tower estimates, while ChatGPT grew 70 percent and Google’s Gemini 166 percent over the same period. Despite that growth, ChatGPT remains the largest A.I. assistant with 1.4 billion monthly users; Gemini has 591 million monthly active users, and Claude holds a share of about 4 percent. Sensor Tower compared seven A.I. assistants: ChatGPT, Claude, Gemini, Meta AI, Grok, Perplexity and Meta’s A.I. agent Muse. Across the group, monthly active users rose 97 percent and revenue from in-app purchases grew 108 percent. Claude’s steep growth began in the United States in March, according to Sensor Tower, which points to OpenAI’s partnership with the U.S. Department of War and a Super Bowl ad campaign as triggers. Claude downloads rose 765 percent year over year in the first quarter, 1,264 percent in the second and 891 percent in the third. Between April and October, 73 percent of Claude users accessed the service only on the web and 17 percent only through the app, while 56 percent of ChatGPT users used only the app. U.S. advertising spending by the A.I. assistants rose 429 percent year over year in the third quarter, with Claude accounting for 15 percent and ChatGPT for 54 percent of the group’s ad