Yet I rarely hear about it being used in production systems and replacing Node.js.

From what I've heard there are two main use cases:

- People use bun as an all-in-one frontend web bundler. Personally, I just use esbuild (and webpack, if I'm working on a system using its module federation, like Jupyterlab). My understanding is bun has a machine-translated port of esbuild (ported to Zig, then to Rust) built into it.

- Claude Code runs on bun.

The second point has to be why Anthropic acquired them.

Somehow claude-cli left open completely nerfs my laptop's battery life. Is this a bun feature?

It famously is extremely memory leaky, with the core team having no idea how to fix it. With the new AI-automated unsafe Rust migration, this piece of slop may never actually become production-ready.

I run it in production for multiple systems.

Ready to migrate back to node once the slop version is out.

Why not deno?

I'm not sure deno has a future.