Join our daily and weekly newsletters for the latest updates and exclusive content on industry-leading AI coverage. Learn More
OpenAI’s ChatGPT has surpassed 400 million weekly active users, a milestone that underscores the company’s growing reach across both consumer and enterprise markets, according to an X post from chief operating officer Brad Lightcap on Thursday.
The rapid expansion comes as OpenAI faces intensifying competition from rivals such as Elon Musk’s xAI and China’s DeepSeek, both of which have recently launched high-performing models aimed at disrupting OpenAI’s dominance. Despite this, OpenAI has seen significant traction in the business sector, with more than two million enterprise users now using ChatGPT at work — doubling from September 2024.
“ChatGPT recently crossed 400M WAU, we feel very fortunate to serve 5% of the world every week,” Lightcap wrote. He also noted that usage of OpenAI’s reasoning model API has surged fivefold since the launch of its o3 Mini model, which is designed to enhance logical inference and structured problem-solving capabilities.
chatgpt recently crossed 400M WAU, we feel very fortunate to serve 5% of the world every week2M+ business users now use chatgpt at work, and reasoning model API use is up 5x since o3 mini launchwe’ll bring GPT-4.5 and GPT-5 to chat and the API soon, with unlimited GPT-5 for… https://t.co/7hfyUcIyBW— Brad Lightcap (@bradlightcap) February 20, 2025
AI is reshaping the workplace: 2 million businesses now rely on ChatGPT
The surge in enterprise adoption represents a crucial validation of OpenAI’s strategy to position ChatGPT as not just a chatbot for casual queries, but as a serious productivity tool for businesses. Companies such as Morgan Stanley, Uber and T-Mobile have integrated OpenAI’s models into their workflows, using AI to generate reports, automate customer service and streamline decision-making.
Notably, OpenAI’s progress comes amid heightened scrutiny over the role of generative AI in business-critical applications. The company recently secured its first federal agency customer, USAID, which is deploying ChatGPT Enterprise to reduce administrative burdens and streamline partnerships, according to FedScoop. The expansion into government contracts suggests OpenAI is succeeding in navigating the regulatory hurdles that have slowed adoption of AI in public-sector institutions.
At the same time, OpenAI is deepening its presence in J …