On December 3, 2025, Anthropic announced it has acquired Bun, a high‑performance JavaScript runtime created by Jarred Sumner, and said the acquisition will accelerate Claude Code — its agentic coding product for developers and enterprises. The announcement came after Claude Code reached a $1 billion run‑rate in November, six months after becoming generally available.
What Bun is and why Anthropic bought it
Bun is an all‑in‑one toolkit that combines a runtime, package manager, bundler and test runner. Founded in 2021 by Jarred Sumner, Bun is designed to improve speed, reliability and the developer experience for JavaScript and TypeScript projects, and Anthropic says it is significantly faster than the leading alternatives. The company positions Bun as essential infrastructure for AI‑led software engineering because it shortens development and test cycles.
Key usage and community metrics cited in Anthropic’s announcement include:
- more than 7 million monthly downloads,
- over 82,000 stars on GitHub,
- adoption by companies such as Midjourney and Lovable.
Claude Code’s growth and Bun’s role
Claude Code became generally available in May 2025. Anthropic describes the product as growing from an internal engineering experiment into a critical tool used by several category‑leading enterprises, including Netflix, Spotify, KPMG, L’Oreal and Salesforce. According to the company, Bun has been instrumental in scaling Claude Code’s infrastructure during that evolution, and the two teams had been close partners for months.
Anthropic also credits the Bun collaboration with directly enabling the recent launch of Claude Code’s native installer.
What will change after the acquisition
Anthropic says Bun will remain open source under the MIT license. The company plans to continue investing in Bun as a runtime, bundler, package manager and test runner for JavaScript and TypeScript, while integrating Bun’s capabilities and team into Claude Code to deliver faster performance, improved stability and new workflows.
Mike Krieger, Chief Product Officer of Anthropic, is quoted in the announcement: "Bun represents exactly the kind of technical excellence we want to bring into Anthropic. Jarred and his team rethought the entire JavaScript toolchain from first principles while remaining focused on real use cases. Claude Code reached $1 billion in run‑rate revenue in only 6 months, and bringing the Bun team into Anthropic means we can build the infrastructure to compound that momentum and keep pace with the exponential growth in AI adoption."
Strategic context and recruiting
Anthropic frames the acquisition as consistent with a disciplined acquisition strategy that targets opportunities to strengthen technical capabilities and leadership in enterprise AI while aligning with the company’s principles and mission. The company also notes recruiting opportunities: engineers interested in joining Anthropic’s team are invited to visit the firm’s careers page.
