AI company Anthropic PBC announced today its first-ever acquisition: Bun, a developer tools startup. The financial terms of the deal were not disclosed.
Founded in 2019, Bun offers an all-in-one JavaScript/TypeScript toolkit designed to streamline and accelerate full-stack development. Its product serves a role similar to Node.js but integrates commonly used standalone tools—such as a package manager, bundler, test runner, and script runner—into a single executable binary.
Built with the Zig programming language and powered underneath by Apple’s JavaScriptCore engine, Bun delivers faster startup times and lower memory consumption compared to runtimes based on V8—the engine behind Node.js and others. In key developer workflows like package installation, building/bundling, test execution, and runtime performance, Bun consistently outperforms alternatives, making it a compelling asset for Anthropic.
Bun maintains broad compatibility with existing Node.js codebases and supports many core Node APIs—including those for file systems, path resolution, and networking—while also implementing module resolution in a manner similar to Node. In essence, Bun can be viewed as a significantly enhanced version of Node.js.
For Anthropic, this acquisition will bring faster performance, improved stability, and new capabilities to users of Claude Code, the company’s AI-powered coding assistant.
Enhancing Claude Code is central to the acquisition, as Bun has already played a pivotal role in scaling the infrastructure that underpins Claude Code’s rapid evolution.
“Bun exemplifies the kind of technical excellence we aim to bring into Anthropic,” said Chief Product Officer Mike Krieger in a blog post announcing the deal. “Claude Code has already generated $1 billion in annualized run-rate revenue within just six months of launch. Bringing the Bun team on board enables us to build the infrastructure needed to accelerate this momentum and keep pace with the exponential growth in AI adoption.”
While this marks Anthropic’s first acquisition, it is unlikely to be its last. The company emphasized that the move aligns with its “strategic and disciplined approach to acquisitions” and stated it will continue seeking opportunities that “enhance our technical excellence, reinforce our position as an enterprise AI leader, and—most importantly—align with our principles and mission.”
Prior to the acquisition, Bun raised $7 million in seed funding in 2022 from investors including Kleiner Perkins Caufield & Byers and Johannes Schickling.
