Router Rosetta tool translates Next.js code between Pages and App Router with citations

A developer built Router Rosetta, a web tool that converts Next.js code and questions between the Pages Router and App Router, addressing a common source of developer confusion. Because both sets of Next.js documentation coexist without clear labeling, developers often apply outdated patterns like getServerSideProps to App Router projects where they are not valid. The tool identifies which router a given code snippet belongs to and provides the equivalent implementation for the other, citing official Next.js documentation for every claim. It is designed to avoid hallucination by refusing to answer queries not covered by its knowledge base, instead of drawing on the underlying model's memory. Router Rosetta is live at router-rosetta.vercel.app and was submitted as part of the Sanity developer challenge.