Anthropic has announced the acquisition of Bun, the JavaScript runtime that has quietly become essential infrastructure for AI-powered development. The timing isn’t coincidental—Claude Code just hit $1 billion in run-rate revenue, only six months after becoming generally available.
From Internal Experiment to Billion-Dollar Product#
Claude Code started as an engineering experiment inside Anthropic. Now it’s a critical tool for some of the world’s largest enterprises including Netflix, Spotify, KPMG, L’Oreal, and Salesforce. The trajectory from May 2025 general availability to billion-dollar milestone in November represents one of the fastest-growing AI products in the market.
Why Bun Matters#
Founded by Jarred Sumner in 2021, Bun has redefined what developers expect from JavaScript tooling. It’s not just a runtime—it combines package manager, bundler, and test runner into a single, blazingly fast toolkit. With over 7 million monthly downloads and 82,000 GitHub stars, companies like Midjourney and Lovable already rely on it.
Anthropic and Bun have been collaborating for months. That partnership directly enabled Claude Code’s native installer and helped the team keep pace with exponential growth. Bringing Bun in-house is about cementing that advantage.
“Bun represents exactly the kind of technical excellence we want to bring into Anthropic,” said Mike Krieger, Anthropic’s Chief Product Officer. “Jarred and his team rethought the entire JavaScript toolchain from first principles.”
What Changes#
For Bun users: nothing immediately. The runtime remains open source and MIT-licensed. Anthropic has committed to continued investment in making Bun the tool of choice for JavaScript and TypeScript developers.
For Claude Code users: expect faster performance, improved stability, and new capabilities as the teams integrate more deeply.
The Strategic Play#
This acquisition signals Anthropic’s broader ambition. They’re not just building AI models—they’re building the infrastructure stack that AI-native development runs on. By owning a critical piece of the JavaScript ecosystem, Anthropic positions Claude Code as more than a coding assistant. It becomes a platform.
The billion-dollar milestone in six months proves the market is ready. Acquiring Bun ensures they can keep building at that pace.