Anthropic made its first acquisition by buying Bun, a high-speed JavaScript runtime, to power its AI coding tool Claude Code. The deal comes as Claude Code reached $1 billion in annual revenue just six months after launch. This acquisition signals a major shift in how AI companies build developer tools and positions Anthropic as a serious player in the enterprise coding market.

What Is Bun and Why Did Anthropic Buy It?

Bun is a JavaScript runtime founded by Jarred Sumner in 2021 that combines runtime, package manager, bundler, and test runner into one toolkit. It's faster than Node.js and has become essential infrastructure for AI-driven software development.

Key facts about Bun:

The acquisition price is in the low hundreds of millions of dollars, making it a significant investment for Anthropic's first-ever acquisition.

Why Anthropic chose Bun:

• Claude Code ships as a Bun executable to millions of users
• Bun creates single-file executables that run without requiring Node.js installation
• The runtime provides fast startup times and works with native addons
• Companies like Midjourney and Lovable already use Bun to increase speed and productivity

Claude Code's Explosive Growth

Claude Code reached $1 billion in run-rate revenue in November 2025, just six months after becoming publicly available in May 2025. This makes it one of the fastest-growing AI developer tools in history.

Enterprise adoption:

The tool changed from an internal engineering experiment to a critical product used by major enterprises worldwide. In late 2024, AI coding tools went from "cool demo" to "actually useful", driving rapid adoption across the industry.

How Bun Powers Claude Code's Infrastructure

Claude Code and Bun have been working together for months before the acquisition. The GitHub username with the most merged pull requests in Bun's repository is now a Claude Code bot that helps fix bugs and run tests.

Technical integration:

• Claude Code ships as a Bun executable
• Bun's single-file compilation makes distribution simple
• The runtime handles fast iteration cycles for AI-generated code
• Native addon support enables powerful functionality

The partnership became natural because both teams focus on speed. When AI agents write code, they generate much more code overall and test it faster. The environment where this code runs must be fast and predictable to keep up with AI output.

What This Means for Developers

If you use JavaScript or TypeScript, this acquisition affects your development environment options.

For Claude Code users:

• Faster performance when generating and testing code
• Improved stability during long coding sessions
• New capabilities rolling out over time
• Better integration between AI tools and JavaScript runtime

For Bun users:

• Bun stays open source under MIT license
• Development continues with same team
• Focus remains on high-performance JavaScript tooling, Node.js compatibility, and replacing Node.js as the default server-side runtime
• More resources and stability for long-term planning

Anthropic is betting on Bun as the infrastructure powering Claude Code, Claude Agent SDK, and future AI coding products. This means significant investment in making Bun better for both AI and traditional development.

The Strategic Vision Behind the Deal

This acquisition reveals Anthropic's strategy for competing in the AI market. While OpenAI focuses on consumer products like ChatGPT, Anthropic targets developers and enterprises.

Anthropic's approach:

• Build deep integration with developer workflows
• Control the full stack from AI model to runtime
• Focus on enterprise customers with serious coding needs
• Create tools that become essential infrastructure

Mike Krieger, Chief Product Officer of Anthropic, said: "Jarred and his team rethought the entire JavaScript toolchain from first principles while remaining focused on real use cases". This matches Anthropic's own philosophy of building fundamental infrastructure.

The deal makes business sense for both sides. Bun had over four years of runway but chose to join Anthropic to skip the monetization chapter and focus on building the best JavaScript tooling.

How This Compares to Competitors

Anthropic's acquisition shows a different strategy than other AI companies.

Company approaches:

Internal financials show Anthropic expects to break even by 2028—two years earlier than OpenAI. The company takes a more disciplined growth path by focusing on profitable enterprise customers rather than expensive consumer expansion.

Funding and Market Position

Anthropic has strong backing from major tech companies. Microsoft and Nvidia pledged up to $15 billion in fresh investment last month, alongside a $30 billion commitment from Anthropic to run Claude Code on Microsoft's cloud. This comes on top of previous investments from Amazon ($8 billion) and Google ($3 billion).

This funding supports Anthropic's aggressive move into developer tooling. The company can afford to acquire infrastructure like Bun because investors believe in the enterprise coding market's potential.

What Happens Next for Bun Development

Bun's roadmap continues with more resources and clearer direction.

Development priorities:

• Maintain Node.js compatibility
• Improve performance for JavaScript and TypeScript
• Optimize for AI coding workflows
• Support Claude Code's growing user base
• Keep community-driven development on GitHub

The Bun team joins Anthropic but keeps its identity. Development happens publicly on GitHub with the same open-source approach. The difference is more funding and direct insight into where AI coding tools are headed.

Impact on the JavaScript Ecosystem

This acquisition affects the broader JavaScript community beyond Claude Code users.

Ecosystem changes:

• More competition for Node.js pushes innovation
• Single-file executables become more common
• Performance becomes critical as AI generates more code
• Developer tools optimize for AI workflows

Other AI coding tools already use Bun, including FactoryAI and OpenCode. As Bun improves under Anthropic, these tools benefit from better infrastructure even though they compete with Claude Code.

Common Questions About the Acquisition

Will Bun become closed source?

No. Bun remains open source and MIT-licensed, and Anthropic committed to continuing this approach.

Does this affect existing Bun users?

Not negatively. You get the same tool with more development resources behind it. Updates should come faster with Anthropic's support.

Will Claude Code only work with Bun?

Claude Code already ships as a Bun executable. The acquisition makes this integration deeper but doesn't force other developers to use Bun.

Can I still contribute to Bun on GitHub?

Yes. Development continues publicly with the same team accepting community contributions.

Tips for Developers Considering Bun

If you're thinking about trying Bun after this news, here's what to know:

Getting started:

• Download from bun.sh or use package managers
• It works as a drop-in replacement for Node.js in most cases
• Start with new projects to avoid migration issues
• Test your dependencies for compatibility

Best use cases:

• New projects starting from scratch
• CLI tools that need fast startup
• Applications requiring single-file distribution
• Projects focused on development speed
• AI-powered development workflows

When to wait:

• Large production systems with complex Node.js dependencies
• Projects requiring specific Node.js versions for compliance
• Teams unfamiliar with troubleshooting runtime issues
• Applications with extensive native module dependencies

The Future of AI-Powered Development

This acquisition points to where software development is headed. AI tools generate more code faster, which demands better infrastructure underneath.

Emerging trends:

• Runtimes built specifically for AI-generated code
• Tools that optimize for machine-written rather than human-written code
• Infrastructure that handles higher volumes of testing and iteration
• Platforms designed for AI agents to build and deploy software

Bun's team gets a front-row seat to where AI coding tools are headed, so they can shape Bun around that future instead of guessing from the outside. This positioning gives Bun advantages in anticipating developer needs.

Key Takeaways

The Anthropic-Bun acquisition matters because it shows how AI companies are building competitive advantages through infrastructure control.

Main points:

• Anthropic paid over $100 million for its first acquisition
• Claude Code hit $1 billion revenue in just six months
• Bun provides essential infrastructure for AI coding tools
• The deal keeps Bun open source while providing more resources
• Anthropic focuses on developers while competitors target consumers
• JavaScript runtime performance matters more as AI generates more code

What this means:

For developers, better tools are coming as AI companies invest in infrastructure. For the industry, expect more acquisitions as AI firms buy developer tools rather than building everything internally. For Bun users, you get a more stable, better-funded project that remains open source.

The acquisition proves that AI coding tools have moved from experiments to essential products. Companies like Netflix and Spotify depend on Claude Code for their development workflows. As these tools become more critical, the infrastructure powering them must be fast, reliable, and built for scale.

Anthropic's bet on Bun shows confidence that JavaScript and TypeScript will remain central to software development even as AI transforms how code gets written. By owning the runtime, Anthropic controls a key piece of the development stack and can optimize it specifically for AI-generated code.

The coming months will show whether this integration delivers the promised speed and stability improvements. For now, the acquisition signals that AI coding tools are here to stay and the companies behind them are making serious infrastructure investments to support rapid growth.