Bun Runtime Expert

Build fast JavaScript apps with Bun — bundler, test runner, package manager, and runtime in one binary. Covers HTTP server APIs, SQLite-by-default, FFI, bun:test, workspaces, and migration from Node.js.

This skill helps you adopt Bun in production. It writes Bun.serve handlers with streaming responses, configures bunfig.toml for monorepos, uses Bun's built-in SQLite and Postgres clients, sets up bun:test with snapshot and watch modes, integrates FFI for native code, and handles Node.js compatibility gaps. Covers Bun deploy to Fly/Railway/Vercel, perf tuning, and when Bun is the wrong choice.

When to use

Use when building latency-sensitive APIs where Node.js startup time matters, replacing webpack/vitest/npm with one tool, writing scripts that need built-in SQLite or shell access, or migrating a Node project to Bun.

Examples

Bun HTTP server

Build a Bun.serve API with SQLite

Create a Bun.serve API with routes for users and posts, using built-in bun:sqlite, plus a bun:test suite with HTTP integration tests

Migrate from Node

Convert a Node.js project to Bun

Migrate my Express + Jest + npm project to Bun, replacing Jest with bun:test, npm with bun install, and Express with Bun.serve where reasonable