According to a recent report from Andreessen Horowitz (a16z), OpenAI’s AI chatbot, ChatGPT, experienced significant growth in the latter half of 2024. The platform saw a notable increase in its user base, with the number of weekly active users doubling in under six months to reach 400 million. This growth can be attributed to the release of new models and features, such as GPT-4o, which introduced multimodal capabilities, and Advanced Voice Mode.

ChatGPT initially gained popularity after its release in November 2022, becoming the fastest app to reach 100 million monthly active users in just two months. By November 2023, it had reached 100 million weekly active users, which grew to 300 million by December 2024 and eventually 400 million in February 2025.

The report notes that initial consumer demand for ChatGPT was driven by novelty, with users interested in trying the app but unsure how it would fit into their daily lives. However, the more recent growth of ChatGPT can be attributed to the release of new models and functionality, such as GPT-4o and Advanced Voice Mode, which have increased user engagement.

The report also highlights the impact of new features on user engagement. For instance, the launch of GPT-4o led to a spike in usage from April to May 2024, while the introduction of Advanced Voice Mode resulted in increased usage from July to August 2024. The o1 model series also contributed to increased usage during September and October 2024.

On mobile, ChatGPT has seen consistent growth, with a 5% to 15% increase in users every month over the past year. Currently, 175 million of ChatGPT’s 400 million weekly active users access the app on mobile devices.

The report also examines the impact of rival apps, such as DeepSeek, which has gained significant traction and now holds the No. 2 spot globally. DeepSeek’s users are even more engaged than those of Perplexity and Claude, although they still lag behind ChatGPT in terms of engagement.

The report provides additional insights, including recommendations for AI developers and coders, rankings of top AI apps by category and revenue, and rankings of top GenAI apps across mobile and web. ChatGPT ranks No. 1 in terms of unique monthly visits on the web and monthly active users on mobile, according to data from Similarweb.