ChatGPT Reaches 1 Billion Users as Claude Gains Rapid Traction

In May 2026, ChatGPT achieved a milestone of 1 billion monthly active users, marking it as the fastest product ever to reach this scale, surpassing platforms like TikTok, Instagram, and YouTube. Despite this achievement, Anthropic’s chatbot Claude is rapidly closing the user base gap.

Data from Sensor Tower reveals that while ChatGPT experienced a 62% year-on-year growth, Claude expanded by 640% over the same period, reaching 56 million monthly active users. Although Claude's user base remains much smaller, its rapid growth rate indicates a swift narrowing of the difference between the two platforms.

Sensor Tower estimates also highlight a substitution effect: U.S. users who installed Claude in the first quarter of 2026 reduced their time on ChatGPT by 5% within a month. This decline suggests that OpenAI’s brand loyalty is no longer guaranteed, as users explore alternative chatbots.

Both OpenAI and Anthropic are preparing to enter public markets. Anthropic confidentially filed for a U.S. initial public offering on June 2, 2026, while OpenAI submitted its confidential S-1 filing on May 22, with Goldman Sachs and Morgan Stanley as lead underwriters, aiming for a debut in the fourth quarter of 2026.

OpenAI reported approximately $13.1 billion in revenue for 2025 and projects annualized revenue near $25 billion. However, the company anticipates a $14 billion loss in 2026, raising questions about the scalability of its business model. According to CMC Markets, profitability is not expected until around 2030.

Anthropic holds a structural advantage in the enterprise sector, with Claude accounting for roughly 40% of enterprise large language model spending, compared to OpenAI’s 27%. Companies in regulated industries have shown a preference for Anthropic’s emphasis on safety, a factor both companies will need to address in their IPO filings.

While ChatGPT’s billion-user milestone is significant, it may represent a plateau. The critical challenge for OpenAI lies in maintaining this user base by converting free users into paying customers and retaining them amid Claude’s faster growth. For consumers, the intensifying competition between ChatGPT and Claude is likely to result in improved products and increased pricing pressure. Neither company appears poised to exit the market, signaling that the AI chatbot sector is evolving into a competitive landscape.