Key facts
- An Anthropic engineer has not written code for five months.
- Claude now authors over 80% of Anthropic's production codebase.
- Claude Code was launched in February 2025.
- The percentage of code authored by Claude has increased significantly since its launch.
An engineer at Anthropic has not written code for five months, as the company's AI model, Claude, now generates the majority of its codebase. As of May 2026, over 80% of the code merged into Anthropic's production environment was authored by Claude. This represents a substantial increase from the low single digits when Claude Code was first introduced in February 2025. The development underscores the increasing capability and integration of AI in software development processes. The article also discusses 'vibe coding,' a trend where plain English is used to have AI write code and build applications. Companies like Anthropic and Google reportedly have AI author up to 90% of their code. Business Insider journalists tested various AI coding tools, creating personal fitness apps, newsroom assistants, and a Pinterest-like application. The guide emphasizes detailed prompts for AI tools and iterative refinement for desired results, noting costs starting around $25 per month and strategies for maximizing free credits.