Bun has been acquired by Anthropic, marking a major shift in the future of JavaScript tooling and AI-powered development. Anthropic is investing in Bun as the foundational infrastructure for Claude Code, the Claude Agent SDK, and upcoming AI coding tools. This move underscores Anthropic’s belief that Bun’s unique capabilities are essential for building the next generation of AI-driven software. What remains unchanged: Claude Code will continue to ship as a Bun executable to millions of users. If Bun breaks, Claude Code breaks. This creates a strong incentive for Anthropic to maintain and improve Bun’s performance and reliability. What’s changing: The acquisition brings Bun into the core of Anthropic’s AI development efforts. The Bun team will continue working full-time on the project, now with access to the resources of one of the world’s leading AI labs. The journey of Bun began nearly five years ago when its creator was building a browser-based voxel game. Frustrated by slow development cycles caused by Next.js’s hot reload times, he began rewriting esbuild’s TypeScript and JSX transpiler in Zig. Within weeks, he had a working prototype. After months of intense work in a small Oakland apartment, Bun v0.1.0 launched in July 2022—a single tool combining a bundler, transpiler, runtime, test runner, and package manager. It quickly gained traction, hitting 20,000 GitHub stars in its first week. The early momentum led to a $7 million seed round from Kleiner Perkins and the recruitment of a small team to San Francisco. Bun v1.0 shipped in September 2023, signaling stability. A Series A of $19 million from Khosla Ventures followed, enabling growth to 14 team members and a larger office. Windows support arrived with Bun v1.1, despite early challenges. Bun v1.2 introduced built-in PostgreSQL and S3 clients, improved Node.js compatibility, and attracted production users at companies like X and Midjourney. Tailwind’s standalone CLI now runs on Bun. Bun v1.3 added a built-in frontend dev server, Redis and MySQL clients, enhanced package installation, and stronger Node.js compatibility. But the real breakthrough came when AI coding tools matured in late 2024. Bun’s ability to compile JavaScript projects into single-file executables proved ideal for distributing AI-powered CLI tools. These binaries run anywhere—no Node.js or Bun installation required—making them perfect for AI agents and developers alike. Tools like Claude Code, FactoryAI, and OpenCode are all built with Bun. The creator of Bun became deeply invested in Claude Code, using it daily. Over time, the GitHub account with the most merged PRs in Bun’s repository became a Claude Code bot. It autonomously identifies bugs, submits fixes with passing tests, and responds to feedback—demonstrating how AI agents can now actively contribute to development. This rapid evolution led to a pivotal decision. Despite Bun having four years of runway and no immediate need to monetize, the team saw a better path: joining Anthropic. After multiple conversations with Anthropic and other competitors, the choice became clear—Anthropic is positioned to lead in AI coding. The acquisition eliminates the need for Bun to pursue traditional monetization strategies. Instead, it can focus entirely on building the best JavaScript tooling for an AI-first world. Bun remains open-source under the MIT license. Development continues publicly on GitHub. Node.js compatibility and Bun’s identity as a drop-in replacement for Node.js are preserved. The team stays full-time, now backed by Anthropic’s resources. The roadmap will evolve closely with the Claude Code team, similar to how Chrome and V8, or Safari and JavaScriptCore, have evolved together—but with greater independence to serve Bun’s diverse user base. For developers, the promise stays the same: Bun will remain fast, reliable, and built for the future of software development. For Anthropic, it’s a strategic move to own the infrastructure beneath the next wave of AI-powered coding. This is more than an acquisition—it’s a convergence of two visions for how software will be built.