386%. That's how much Claude's share of AI-generated referral traffic grew from January to April 2026, according to a study of 101,574 websites across 250 countries. ChatGPT, in the same four-month window, grew 1.53%.
The research tracked which AI platforms sent users to external websites between January 2025 and April 2026 - a proxy for how people use these tools during research and task-completion workflows. March 2026 stands out: a single month with 2.6x growth, the largest single-month gain in Claude's history.
Context that matters: despite that 386% surge, Claude still accounts for only 1.40% of total AI referral traffic. ChatGPT still dominates the category by a wide margin. What's shifting isn't Claude overtaking the leader - it's the pace of the gap closing, and what the traffic patterns suggest about who's using each platform.
March Was Not Routine
A 2.6x single-month spike typically reflects a specific product moment rather than organic diffusion. The March surge coincides with Claude's expanded tool-use capabilities, broader availability of its agentic features, and growing enterprise adoption - all of which tend to generate the kind of research-heavy sessions that produce outbound clicks.
Referral traffic, as a metric, naturally favors research-oriented use. When someone uses ChatGPT to draft an email or rewrite a paragraph, they don't end up clicking through to five external sites. When someone uses an AI assistant to compare vendors, trace a claim to a source, or dig through documentation, they do. Claude's growing referral share suggests its user base skews toward that second type of session.
What 1.40% Actually Means
The 1.40% total share figure is easy to dismiss as small. In absolute terms, it is. But referral traffic systematically undercounts use cases that don't generate outbound clicks - creative writing, summarization, code generation, and in-app AI features all fail to appear here. The 1.40% represents a specific kind of usage: exploratory, research-heavy, and professionally oriented.
For marketers, content researchers, and small business owners who track which AI tools actually drive traffic to their sites, Claude's trajectory is a more meaningful signal than its overall market share suggests. The users it's adding at speed aren't casual consumers trying an AI chatbot for the first time. They're people using AI as part of a workflow.
Whether Anthropic can hold that audience as ChatGPT and Gemini keep adding research and browsing features is a separate question. But the March spike suggests Claude is pulling in that kind of user fast, and 1.40% of a large and growing category leaves significant room to run.