Technology
Next.js 15: The Developer's Guide to App Router, Server Components, and Turbopack
Next.js 15 shipped in October 2024 and made the App Router the official default for new projects, stabilized Turbopack for development builds, and introduced async request APIs that changed how developers access cookies, headers, and search parameters. Next.js 16 (October 2025) extended Turbopack to production. This guide covers the concepts, architecture decisions, and practical trade-offs of the Next.js 15 era, which remains the most widely deployed major version.