Free Anthropic Just Bought Bun.js. 's Why.

Anthropic just acquired Bun. First acquisition ever for the company behind Claude and Claude Code.

Most takes I've seen focus on speed. "Claude Code needs fast tooling." "Milliseconds matter at scale." That's not wrong, but it's not the interesting part either.

The interesting part is what this signals about where AI development is headed.

Bun is a JavaScript runtime that's faster than Node.js. It's also a package manager, bundler, and test runner—all in one. It's open source, MIT-licensed, and has about 7 million monthly downloads.

Anthropic makes Claude. Their coding tool, Claude Code, has been growing fast—it hit $1 billion in annual run-rate revenue six months after public launch. That's not a typo. Six months.

Here's the connection: Claude Code ships as a Bun executable. When you install Claude Code, you're running Bun. This isn't a loose partnership but a dependency.

Here's how developer tooling has evolved in the AI era:

Phase 1: LLMs generate, humans run ChatGPT writes code, you copy-paste it, you run it, you fix it. The model never touches your environment.

Phase 2: LLMs + tool use Claude/GPT can call tools via function calling, MCPs, etc. The model asks external systems to do specific things. But it's still orchestrated, constrained, pre-defined.

Phase 3: Agents that improve by building and running their own tools This is where it gets interesting. Agents that don't just call pre-built tools, but write new ones on the fly. Generate a script, compile it, execute it, observe results, iterate. Spawn sub-agents. Orchestrate parallel workloads.

Source: Dev.to