Anthropic buys Bun as Claude Code hits USD 1B run rate

Anthropic says the past six months have changed how many teams build software. Claude Code, which became generally available in May 2025, has moved from an internal experiment to a mainstream coding assistant adopted by Netflix, Spotify, KPMG, L’Oreal, and Salesforce. The company says it crossed USD 1 billion in run-rate revenue in November, making it one of the fastest-growing AI tools in the developer space.

With AI now part of day-to-day engineering work, Anthropic argues that the performance of underlying tools has become more important. That is what drew the company to Bun.

Why Bun matters for Anthropic

Bun launched in 2021 as a rethink of the JavaScript toolchain. It combines a runtime, package manager, bundler, and test runner. Its speed has made it popular with developers working on AI-driven products, and it now sees more than 7 million monthly downloads and over 82,000 GitHub stars. Companies such as Midjourney and Lovable use it to accelerate development pipelines.

Anthropic says Bun has already played a quiet but important role inside Claude Code. The two teams have partnered for months, including on Claude Code’s native installer. That existing work made the acquisition feel like a natural next step.

What Anthropic says about the acquisition

Mike Krieger, Chief Product Officer at Anthropic, called Bun “exactly the kind of technical excellence we want to bring into Anthropic.” He said founder Jarred Sumner and his team rebuilt the JavaScript ecosystem from first principles and kept their focus on practical developer needs.

Krieger added that the acquisition will help Anthropic scale Claude Code’s infrastructure to match rising AI adoption. With more enterprises relying on coding agents, Anthropic wants faster, more reliable tooling underneath.

What changes for developers

Anthropic says Bun will stay open source under the MIT license. The company plans to keep improving Bun as a general-purpose JavaScript and TypeScript runtime while weaving it deeper into Claude Code’s workflows.

For developers already using Claude Code, Anthropic promises faster performance, better stability, and new features over time. The company also says the deal supports its broader approach to acquisitions: buying technology that strengthens its engineering foundation and aligns with its principles.

Looking ahead

Anthropic is pitching the acquisition as a step toward the next generation of software development. As coding agents become more common, the company wants its platform to handle heavier workloads and more complex projects. Bun gives it a toolset built for speed, which could help Claude Code maintain momentum in a crowded AI-developer market.