Artificial intelligence company Anthropic has announced its acquisition of Bun, a popular JavaScript runtime, in a strategic move to accelerate the development of its AI-powered coding assistant, Claude Code. The acquisition comes just after Claude Code achieved a major financial milestone, reaching $1 billion in run-rate revenue only six months after its public launch.
The integration of Bun and its development team is expected to enhance the performance and capabilities of Anthropic's tools for software engineers, signaling a deeper investment in the infrastructure that powers modern AI-driven development.
Key Takeaways
- Anthropic has officially acquired Bun, a high-performance JavaScript toolkit founded in 2021.
- The acquisition aims to strengthen Anthropic's AI coding product, Claude Code.
- The move follows Claude Code reaching a $1 billion run-rate revenue milestone in November 2025, just six months after its public release.
- Bun will remain open source and MIT-licensed, with Anthropic committing to continued investment in its development for the broader community.
A Strategic Move in the AI Arms Race
Anthropic's purchase of Bun is a significant step in bolstering its position within the competitive enterprise AI market. By bringing Bun's technology and team in-house, the company aims to create a more integrated and efficient ecosystem for developers using its AI models.
Bun, created by founder Jarred Sumner in 2021, gained substantial traction in the developer community for its speed and efficiency. It serves as an all-in-one toolkit, combining a runtime, package manager, bundler, and test runner, which simplifies and accelerates the software development process.
What is a JavaScript Runtime?
A JavaScript runtime is an environment that allows JavaScript code to be executed outside of a web browser. Tools like Bun provide the necessary components for developers to build, test, and run server-side applications, command-line tools, and other software, making them a fundamental part of the modern web development stack.
The relationship between the two companies was already established, with Anthropic being a close partner of Bun for several months. This collaboration was reportedly instrumental in scaling Claude Code's infrastructure and contributed to the recent launch of its native installer.
Fueling the Growth of Claude Code
The primary driver for the acquisition is the rapid success of Claude Code. Launched to the public in May 2025, the AI coding assistant quickly found a footing in major corporations. Companies like Netflix, Spotify, KPMG, L’Oreal, and Salesforce are listed among its enterprise users.
Its growth has been remarkable, hitting the $1 billion run-rate revenue mark in November 2025. This metric indicates the company's projected annual revenue based on its current monthly earnings, highlighting strong and consistent demand from the market.
"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," said Mike Krieger, Chief Product Officer of Anthropic.
Krieger emphasized the technical fit between the two teams, stating that Bun's focus on rethinking the developer experience from the ground up aligns with Anthropic's own product philosophy.
Bun by the Numbers
- 7 million+ monthly downloads
- 82,000+ stars on GitHub
- Adopted by companies like Midjourney and Lovable
What the Acquisition Means for Developers
For developers currently using Claude Code, Anthropic promises the acquisition will lead to tangible benefits. These include faster performance, improved stability, and new capabilities integrated directly into their workflows.
Crucially, Anthropic has confirmed that Bun will remain an open-source project under its existing MIT license. The company stated its intention to continue investing in Bun to ensure it remains a top choice for all JavaScript and TypeScript developers, not just those within the Anthropic ecosystem.
Investing in Foundational Infrastructure
The acquisition underscores a growing trend in the AI industry: as AI models become more powerful, the underlying software and hardware infrastructure becomes critically important. Efficient, fast, and reliable tools are essential for developers to build and deploy AI-powered applications at scale.
Bun's reputation for high performance makes it a valuable asset. By optimizing the entire JavaScript toolchain, it helps developers build and test applications with greater velocity, a key advantage in the fast-paced world of AI development.
Anthropic framed the decision as part of a "strategic, disciplined approach to acquisitions." The company stated it will continue to seek opportunities that enhance its technical capabilities and strengthen its leadership in enterprise AI, while staying aligned with its core mission and principles.
With the integration of the Bun team, Anthropic is positioning itself not just as a provider of AI models, but also as a builder of the fundamental tools that will shape the next generation of software engineering.