Bun npm Compatibility: Which Packages Work, Which Don't, and Why

,## The Bun Promise vs. Reality,Bun promises to be a drop-in replacement for Node.js. The marketing is compelling: 25x faster package installation,TypeScript execution without transpilation,built-in SQLite support. But if you,re considering switching from Node + npm to Bun, you need to know the real story about npm compatibility.

Here"s what we found: ~87% of the top 1,000 npm packages work with Bun without modification, but the remaining 13% expose a painful truth—"drop-in replacement" doesn"t mean "zero configuration replacement."

Let"s break down which packages work, which don"t, and why.

Category 1: The Green Zone (Works Out of the Box)

~70% of packages live here, and they include most of what you use daily:

• React ecosystem: React, React Router, Next.js, Remix, Astro
• HTTP frameworks: Express, Fastify, Hono, Elysia
• Utilities: lodash, date-fns, zustand, axios, got
• Build tools: esbuild, tsup (when used as a library)
• TypeScript: tsc works; Bun runs .ts files directly without transpilation

Why they work: These packages avoid Node.js-specific internals. They use standard JavaScript APIs, don"t rely on C++ native modules, and don"t depend on undocumented Node internals.