Topline
ChatGPT became the fastest app ever to reach 1 billion monthly active users and still holds the top spot in the AI app market, but competitors including Anthropic’s Claude and Google’s Gemini are gaining ground and, in some areas such as monetization, outperforming OpenAI’s app, according to a new Sensor Tower report.
Sensor Tower’s State of AI report said ChatGPT’s iOS and Android apps reached 1 billion monthly active users last month, just three years after first launching on mobile app stores.
Although ChatGPT continues to lead in total monthly users, the report found its market share slipped below 50% for the first time in March, a sharp decline from 81% in March 2024.
Anthropic’s Claude has posted strong user growth since the beginning of 2026 and is leading rivals in monetization, with 13% of its iOS user base paying for a subscription, compared with 8% for ChatGPT.
Claude is also generating more revenue per user than ChatGPT, bringing in about 1.5 times as much on average—$2.76 per user versus $1.74 for OpenAI’s app.
Even with ChatGPT remaining the largest AI app by monthly users across most countries outside Russia and China, Google’s Gemini is emerging as the fastest-growing option in major markets including the United States, Canada, much of the European Union, Japan and South Korea.
While ChatGPT remains the biggest AI app by monthly users in most countries except Russia and China, Google’s Gemini is the fastest growing in key markets like the U.S., Canada, most of the European Union, Japan and South Korea.
OpenAI’s app, however, remains the best at retaining new users who sign up each month, with a user retention rate of 86% last month—though Claude’s is now closing the gap, having risen to 73.7%.
Did ChatGPT’s Pentagon deal spark a loss of users?
ChatGPT has a definite early-mover advantage, as the report notes: “users remain willing to try alternative AI assistants.” This became most evident in March this year as OpenAI’s decision to sign an agreement with the Pentagon—after Anthropic’s blacklisting—triggered a surge in uninstalls of the ChatGPT app, likely in protest. ChatGPT uninstalls peaked at 202% above its usual numbers in the second week of March, the report shows. The Claude app was the biggest beneficiary of this uninstall spree, as its global market share rose from 5.1% in February to 10% in April.
Tangent
The Wall Street Journal reported last week that OpenAI was considering major price cuts for its AI tools in a bid to compete with rival Anthropic. While this is directed at enterprise customers and won’t directly affect app spending, it comes at as the monetization of AI platforms and the cost of using agents is facing growing scrutiny. On the consumer apps front, Google slashed the subscription price of its cheapest Gemini AI Plus plan from $8 per month to $5 per month earlier this month. OpenAI’s cheapest “Go” tier pricing remains at $8 per month. Claude, on the other hand, does not offer a “lite” or low-cost tier for users as its base plans start at $20 per month. ChatGPT, Gemini and Claude’s monetization efforts are likely to face some pressure as Apple begins to roll out Siri AI later this year, which has features that partly run locally on a user’s iPhone or other Apple devices instead of relying on a subscription.
Big Number
$4.25 billion. That is how much consumers are expected to spend on AI apps in the first half of 2026, according to the Sensor Tower report. This is up from $1.83 billion in H1 2025 and $3.1 billion in H2 2025.
