I stopped hardcoding locales, and adding a language became a one-line change

Most i18n tutorials stop at "put your strings in a JSON file". That covers labels. It does not cover the thing that actually breaks: URLs. I run a personality test site in five locales (French, English, Brazilian Portuguese, European Portuguese, Spanish). Same site, five language trees, roughly 96 articles each. The first version had the shape every project seems to grow by accident: $prefix = $locale === 'en' ? '/en' : '' ; That line, or a cousin of it, spread across controllers, views and helpers. Every one of them was correct when written and wrong the moment a third locale showed up. The bug it produces is the worst kind: nothing throws, the page renders, and the Spanish version quietly links to French URLs. The rule that fixed it One rule, enforced by a test: no locale literal anywhere outside the config file. Not in controllers, not in views, not in helpers. If code needs to know something about a locale, it asks the config. Adding a locale then becomes: content files, plus one entry in config/locales.php . Nothing structural. 'default' => 'fr' , 'available' => [ 'fr' , 'en' , 'pt-br' , 'pt-pt' , 'es' ], Three helpers cover essentially every call site: locale_prefix () // '' for the default locale, '/es' otherwise locale_url ( '/disc' ) // prefixed, canonical, ready to print locale_slug ( 'groupe' ) // the localized route segment The part nobody warns you about: slugs are data Labels translate. Slugs are a different problem, because a slug is simultaneously a URL, a cache key, an SEO asset and a foreign key into your own content. The decision that saved me: one locale is canonical, always. French, in my case. Every slug in every other language resolves back to a French slug before anything else happens. $slugs = app ( SlugService :: class ); $slugs -> toLocale ( 'quatre-tendances' , 'es' ); // 'cuatro-tendencias' $slugs -> resolveToCanonical ( 'cuatro-tendencias' ); // 'quatre-tendances' Without that pivot you get N-to-N translation tables and, eventually, two