How to setup i18n translated URL routes in Next.js?

You can achieve translated URL routes by leveraging rewrites in your next.config.js file.

module.exports = {
    i18n: {
        locales: ['en', 'de', 'es'],
        defaultLocale: 'en'
    },
    async rewrites() {
        return [
            {
                source: '/de/uber-uns',
                destination: '/de/about',
                locale: false // Use `locale: false` so that the prefix matches the desired locale correctly
            },
            {
                source: '/es/nosotros',
                destination: '/es/about',
                locale: false
            }
        ]
    }
}

---

Furthermore, if you want a consistent routing behaviour during client-side navigations, you can create a wrapper around the next/link component to ensure the translated URLs are displayed.

import { useRouter } from 'next/router'
import Link from 'next/link'

const pathTranslations = {
    de: {
        "https://stackoverflow.com/about": '/uber-uns'
    },
    es: {
        "https://stackoverflow.com/about": '/sobrenos'
    }
}

const TranslatedLink = ({ href, children }) => {
    const { locale } = useRouter()
    // Get translated route for non-default locales
    const translatedPath = pathTranslations[locale]?.[href] 
    // Set `as` prop to change displayed URL in browser
    const as = translatedPath ? `/${locale}${translatedPath}` : undefined

    return (
        <Link href={href} as={as}> 
            {children}
        </Link>
    )
}

export default TranslatedLink

Then use TranslatedLink instead of next/link in your code.

<TranslatedLink href="https://stackoverflow.com/about">
    <a>Go to About page</a>
</TranslatedLink>

Note that you could reuse the pathTranslations object to dynamically generate the rewrites array in the next.config.js and have a single source of truth for the translated URLs.