Anthropic's seven co-founders used a letter attached to the company's public IPO filing to pledge that Claude will never carry advertising, The Information reported on October 26. The founders wrote that the only reason Claude exists is to give people helpful answers, and that once advertising becomes part of a company's revenue targets, pressure inevitably builds to drive user engagement. 'We will ensure Claude is not swayed by that kind of pressure,' they added.

The pledge draws the sharpest line yet between the two biggest consumer chatbots. OpenAI began as a consumer chatbot company, now shows ads to free ChatGPT users, and expects advertising to become a major revenue source over the next few years; Anthropic has needled it on exactly this point before, running a Super Bowl ad in February with the slogan 'Ads are coming to the AI world, but not to Claude.'

Staying ad-free does not mean staying quiet. The same filing shows Anthropic is itself a major advertiser: its marketing and advertising expenses rose by $170 million in 2025 and by a further $273 million in the first half of 2026, spent on media placements supporting product launches.