The growing market for AI chatbots remains dominated by ChatGPT, which captured more than 81% of combined website and app activity across six services in September 2026, Graphite estimated.
Graphite estimated a record 61.35 billion ChatGPT web and app sessions that month. Across the six chatbots, sessions reached 76 billion in September 2026, up 37% from a year earlier, based on Similarweb data.
ChatGPT sessions were largely flat from July 2025 through June 2026 after earlier rapid growth. They began rising again in July 2026, Graphite said.
No rival chatbot reached a 10% share of the six-service total. Claude and Gemini also gained sessions over the past year, though each began at a lower level.
The comparison covers ChatGPT, Gemini, Claude, Grok, Perplexity and DeepSeek. It combines website visits with mobile app sessions; those counts do not represent individual users.
