How we rebuilt Cloudflare Workers’ module registry for Node.js compatibility

Cloudflare rebuilt workerd's module registry from scratch so ESM, CommonJS, and WebAssembly module resolution match Node.js semantics directly, rather than approximating them. The rewrite gives every module a single shared instance of Node's built-in modules, makes import.meta.resolve() work correctly, validates import attributes, and matches Node's exact behavior for require() calls against ESM modules. Cloudflare says these are the specific gaps that caused Node.js applications ported to Workers to hit module-resolution bugs that only surfaced at runtime, since the prior implementation approximated Node's behavior rather than replicating it. The new resolution logic sits behind a compatibility flag, alongside a newly uniform 64 MiB bundle limit applied across all Workers plans. For teams running existing Node.js codebases on Workers, enabling the flag removes a specific, previously hard-to-diagnose class of failures without requiring changes to application code.