Anthropic closes in on OpenAI as US business use surges

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Anthropic is gaining ground on OpenAI in the race for paying customers, as new data points to rising business adoption and a levelling-off in its rival’s growth.

Nearly one in three US businesses paid for Anthropic’s tools in March, according to data from payments group Ramp, marking a rise of more than 6 percentage points from the previous month.

OpenAI retains its early lead in the US, but business adoption of the ChatGPT-maker’s tools was flat at 35 per cent, according to Ramp’s data based on $100bn in annual card and invoice spending from 50,000 customers.

The divergence reflects Anthropic’s recent rapid growth owing to strong interest in its Claude Code products and array of “plug-ins” designed to help automate aspects of white-collar jobs.

OpenAI’s surge following the launch of ChatGPT in November 2022 has given it a strong lead, particularly in the consumer market. OpenAI has said it currently has 900mn weekly active users with just over 5 per cent paying for its services.

Its early, explosive growth is proving hard to sustain. Downloads of ChatGPT rose 5 per cent in the month to March, according to data from market researchers Sensor Tower. Over the same period, global downloads of Anthropic’s Claude chatbot tripled to 21mn.

In March, ChatGPT’s weekly active users fell month-on-month in the US for the first time since the start of 2024, according to figures from Apptopia.

OpenAI said it did not recognise the data cited by the FT. The company said that its AI coding agent Codex hit 3mn weekly users, up from 2mn last month.

It said: “Our APIs now process more than 15bn tokens per minute. ChatGPT has six times the monthly web visits and mobile sessions of the next largest AI app. Our ads pilot reached $100mn run rate in six weeks. That’s growth.”

Anthropic’s business appears to have been unaffected by its row with the US defence department over recent weeks, with a US court temporarily blocking the Pentagon’s effort to label the start-up a supply-chain risk.

The company said this week it had reached $30bn in annualised revenue, up from $9bn at the end of 2025.

Charlie Dai, VP and principal analyst at Forrester, said the data points to a “clear shift in momentum” towards Anthropic.

“What’s notable is that this growth is continuing even after the US government flagged potential supply-chain risks,” he said.

“For many companies, factors like how well the models perform, how easy they are to work with, and how well they fit enterprise needs matter more than short-term political or regulatory concerns.”

OpenAI is making a series of changes designed to boost its prospects ahead of its own plans for a blockbuster IPO.

This includes a recent management shake-up, with a greater focus on core business lines over “side quests”, which led it to shutter its Sora video generation platform.

Anthropic’s recent growth demonstrates that its strategy to initially target software developers and other professionals before moving to a wider audience is paying off, said Ara Kharazian, economist at Ramp.

“Anthropic has been extremely successful at going from power users and early adopters to something that is applicable outside of that ecosystem.”

Anthropic’s products are now more widely adopted across US information, financial and professional services than OpenAI’s, but are also growing quickly in sectors such as construction and hospitality, Ramp’s data showed.

OpenAI has previously disputed the accuracy of Ramp’s numbers, saying that “multimillion-dollar contracts” at large enterprises were not captured by Ramp’s data.

“It’s a bit like saying global lemon sales can be calculated based on my kid’s lemonade stand,” the company told the FT last month.

Ramp’s co-founder Eric Glyman responded on X that its corporate payments platform processes up to 1 per cent of US GDP and its numbers are “consistent” with OpenAI and Anthropic’s revenue figures.

Anthropic said it does not comment on third-party data.