Bun Compatibility in 2026: npm, Node.js, and Next.js -- What Works

A practical 2026 compatibility map for Bun covering Node.js API support, npm package compatibility, and Next.js runtime behavior. Core Node.js built-ins (fs, path, http, crypto, buffer) work reliably. Native addons using node-gyp/N-API are the main blocker since Bun uses JavaScriptCore instead of V8 — bcrypt, canvas, and argon2 break, while sharp now works via WebAssembly fallback. Pure JS/TS packages run without issues. For Next.js, using Bun as the package manager is a safe win; using it as the full runtime works for most projects but has edge cases with middleware and some plugins. Recommended use cases include CLI tools, standalone APIs with Prisma/Drizzle, monorepo management, and CI test running. A step-by-step readiness checklist is provided to audit any project in ~30 minutes.