Next.js is a React framework from Vercel, and is the inspiration for Sapper. There are a few notable differences, however:
src/routes/blog/[slug].svelteroutes directory. These are just .js files that export functions corresponding to HTTP methods, and receive Express request and response objects as arguments.<a> elements, rather than framework-specific <Link> components. That means, for example, that this link right here, despite being inside a blob of HTML, works with the router as you'd expect.