Anthropic acquires JavaScript runtime Bun, Claude Code generates $1.5 billion in revenue in just six months



On December 2, 2025, developer Jared Sumner announced on his blog that his JavaScript runtime, Bun , had been acquired by Anthropic. Anthropic followed suit on December 3, announcing the acquisition of Bun and announcing that its AI coding tool, Claude Code, had reached a major milestone of $1 billion in annualized revenue just six months after its public release.

Anthropic acquires Bun as Claude Code reaches $1B milestone \ Anthropic
https://www.anthropic.com/news/anthropic-acquires-bun-as-claude-code-reaches-usd1b-milestone

Bun is joining Anthropic | Bun Blog
https://bun.com/blog/bun-joins-anthropic

Bun was developed by Sumner in 2021, and the impetus for it came from the fact that when he was creating a browser game, it took 45 seconds to change the code and see the results, which was frustrating. Since much of that time was spent in the existing development tool's process of reflecting the changes, Sumner ported a transcompiler written in another programming language to the faster language Zig . Bun was developed in just three weeks, but achieved overwhelming speed improvements of 3 to 197 times compared to existing major tools.



According to Sumner, Bun is an all-in-one toolkit that combines runtime, package manager, bundler, and test runner, and is downloaded more than 7 million times per month. It has grown to have more than 82,000 stars on GitHub. Companies such as Midjourney and Lovable are also using Bun to improve their development productivity.

Anthropic's acquisition of Bun is aimed at further accelerating Claude, the world's smartest and most capable AI model for developers. Claude Code is distributed to millions of users as Bun executable files, and if Bun malfunctions, Claude Code will also stop working. Anthropic states, 'Bun is optimized for reliability and speed, making it an essential infrastructure supporting AI-driven software engineering.'

Sumner said that even after the acquisition, Bun will remain open source and available under the MIT license. Development will continue by the same team and will be publicly available on GitHub. He also said that the roadmap remains unchanged: improving JavaScript tooling speed, improving compatibility with Node.js, and replacing Node.js as the standard runtime for server-side JavaScript.

Through this acquisition, Bun's development team will help make tools like Claude Code and Claude Agent SDK faster and more lightweight, while also gaining exposure to cutting-edge AI coding tools, allowing Bun to quickly grasp upcoming technological trends and use those insights to improve Bun itself.



Mike Krieger, Chief Product Officer at Anthropic, said he highly values the technical capabilities of Bun's development team, which has rethought the JavaScript toolchain from scratch and focused on practical use cases, and that this acquisition will further accelerate the construction of infrastructure to accompany the widespread adoption of AI.

The specific terms of the acquisition, such as the purchase price, have not been disclosed at the time of writing. The Financial Times also reported that Anthropic is preparing to go public in 2026 and has begun discussions with major investment banks about the possibility of issuing an initial public offering (IPO).

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