Next.js i18n with the App Router: Complete 2026 Guide
Complete guide to internationalizing a Next.js 15 App Router app in 2026. Covers why the built-in i18n config is gone, the [locale] segment and generateStaticParams, middleware locale detection, the zero-dependency dictionaries pattern, the full next-intl setup (routing, request config, plugin, middleware), Server vs Client Component translations, ICU plurals and rich text, number/date/currency formatting, a language switcher, hreflang metadata, static rendering with setRequestLocale, RTL, and exporting messages to PO files.