Market intelligence firm Sensor Tower reported that OpenAI's ChatGPT, while maintaining its leadership in the AI chatbot sector, has shown signs of decelerating user growth. Concurrently, Google's Gemini has demonstrated an acceleration in download growth, monthly active users, and in-app engagement metrics, according to the firm's recent data.
As of November 2025, ChatGPT accounted for 50% of global mobile downloads and 55% of global monthly active users. However, from August to November, ChatGPT's global monthly active users (MAUs) increased by approximately 6%, reaching an estimated 810 million. Sensor Tower suggests this growth rate may indicate the AI chatbot is nearing market saturation. During the same three-month period, Google Gemini's global MAUs surged by roughly 30%. On a year-over-year basis, ChatGPT's MAUs climbed 180%, while Gemini's rose 170%.
The report highlighted Google's increasing competitive positioning, noting that approximately twice as many U.S. Android users engage with Gemini directly through the Android operating system compared to its standalone mobile application. This integration provides Google with a broader reach, particularly in the global market where the Android operating system is dominant. The release of Gemini's new image generation model, Nano Banana, has been identified as a key factor driving its increased adoption.
Sensor Tower's analysis further indicated a shift in market share. Between May and November 2025, Gemini's share of global monthly active users across top AI chatbot apps increased by three percentage points. Conversely, ChatGPT's share of global MAUs decreased by three percentage points over the four-month period from August to November 2025. Other competitors, including Perplexity and Claude, also recorded substantial year-over-year growth in 2025, with Perplexity up 370% and Claude up 190%.
User engagement metrics also reflected this changing dynamic. Gemini app users' average daily time spent in the application more than doubled from March to November, reaching 11 minutes per day in November, a 120% increase. This surge coincided with the reported popularity of Nano Banana. In contrast, ChatGPT users' daily time spent increased by only 6% during the same timeframe and experienced a 10% decline in November compared to July. Internally, OpenAI CEO Sam Altman reportedly issued a "code red" memo, instructing staff to prioritize product enhancements in areas such as personalization, reliability, and image generation in response to the evolving market landscape.
