Anthropic's Claude has become one of the fastest-growing AI platforms out there. But here's the twist: its explosive growth isn't really hurting OpenAI.
According to Similarweb, Claude's website traffic jumped roughly 770% between September 2024 and March 2026. Over the same period, ChatGPT's web visits grew about 84%. That means Claude expanded at roughly nine times the pace of OpenAI's chatbot.
On the surface, that looks like Anthropic is rapidly closing the gap. But a second dataset tells a very different story.
ChatGPT vs Claude: The Overlap
New Similarweb audience overlap data shows that the vast majority of Claude users also use ChatGPT in the same month. In contrast, only a relatively small share of ChatGPT users also visit Claude—though that percentage has steadily increased over the past year.
Taken together, the two datasets suggest Claude's rapid growth isn't primarily coming from users abandoning ChatGPT. Instead, many users appear to be adding Claude alongside OpenAI's chatbot rather than replacing one with the other.
That points to an AI market that is becoming more competitive without necessarily becoming winner-takes-all.
Growing the Market
Similarweb says the generative AI landscape has evolved from a single-platform market into a genuinely competitive one, with ChatGPT remaining the largest platform while newer entrants continue gaining traction. Claude's traffic growth reflects that shift, even as ChatGPT continues adding users from a much larger base.
The broader user figures tell a similar story. ChatGPT is estimated to have around 1 billion monthly active users, while Claude has roughly 56 million, according to industry estimates. That leaves OpenAI with a commanding lead in scale even as Anthropic posts significantly faster percentage growth.
The dynamic mirrors many mature technology markets, where challengers often grow much faster than incumbents simply because they start from a much smaller base.
The Bigger Picture
For investors, the more important takeaway may not be which chatbot is growing the fastest, but how consumers are using them. If users are increasingly relying on multiple AI assistants for different tasks, the competitive landscape looks very different from a traditional winner-takes-all technology battle.
That could help explain why companies across the AI ecosystem—from model developers to cloud providers and semiconductor firms—continue investing aggressively despite the emergence of several well-funded competitors.
Claude's explosive growth shows Anthropic is winning users. The overlap data suggests OpenAI is still winning habits. And in platform businesses, becoming the default destination is often a more durable competitive advantage than posting the fastest growth rate.
