How to Add next-intl Internationalization to Next.js 15: Step-by-Step Guide

npm install next-intl

1// src/i18n/routing.ts
2import {defineRouting} from 'next-intl/routing';
3
4export const routing = defineRouting({
5  locales: ['en', 'fr', 'ar', 'es'],
6  defaultLocale: 'en'
7});

// src/i18n/navigation.ts
import { createNavigation } from 'next-intl/navigation';
import { routing } from './routing';

export const { Link, redirect, usePathname, useRouter, getPathname } = createNavigation(routing);

1// src/i18n/request.ts
2import { getRequestConfig } from 'next-intl/server';
3import { hasLocale } from 'next-intl';
4import { routing } from './routing';
5
6export default getRequestConfig(async ({ requestLocale }) => {
7    const requested = await requestLocale;
8    const locale = hasLocale(routing.locales, requested)
9        ? requested
10        : routing.defaultLocale;
11
12    const [seoMessages] = await Promise.all([
13        import(`../messages/seo/${locale}.json`).then(module => module.default).catch(() => ({})),
14    ]);
15
16    return {
17        locale,
18        messages: {
19            seo: seoMessages,
20        }
21    };
22});

1// src/app/[locale]/about/layout.tsx
2import { NextIntlClientProvider } from "next-intl";
3
4export default async function AboutLayout({
5  children,
6  params,
7}: {
8  children: React.ReactNode;
9  params: Promise<{ locale: string }>;
10}) {
11  const { locale } = await params;
12
13  const [about] = await Promise.all([
14    import(`@/messages/about/${locale}.json`).then((mod) => mod.default),
15  ]);
16
17  const messages = { about };
18  return (
19    <NextIntlClientProvider locale={locale} messages={messages}>
20      {children}
21    </NextIntlClientProvider>
22  );
23}

src/messages/about/en.json
src/messages/about/fr.json
src/messages/about/ar.json
src/messages/about/es.json

{
  "header_story": "Our Story",
  "header_title1": "We're Building",
  // ...
}

1import { useTranslations } from "next-intl";
2
3export default function AboutHeader() {
4  const t = useTranslations("about");
5  return <h1>{t("header_title1")}</h1>;
6}

1// filepath: src/components/LanguageSelector/index.tsx
2"use client";
3
4import React, { useState, useRef, useEffect } from "react";
5import { useParams, useRouter } from "next/navigation";
6import { cn } from "@/lib/utils";
7import { IconLanguage, IconChevronDown } from "@/lib/icons";
8
9interface Language {
10  code: string;
11  name: string;
12  rtl: boolean;
13}
14
15const languages: Language[] = [
16  { code: "en", name: "English", rtl: false },
17  { code: "fr", name: "Français", rtl: false },
18  { code: "es", name: "Español", rtl: false },
19  { code: "ar", name: "العربية", rtl: true },
20];
21
22export default function LanguageSelector() {
23  const [isOpen, setIsOpen] = useState(false);
24  const dropdownRef = useRef<HTMLDivElement>(null);
25  const router = useRouter();
26  const params = useParams();
27  const currentLocale = typeof params.locale === "string" ? params.locale : "en";
28  
29  const currentLanguage = languages.find((lang) => lang.code === currentLocale) || languages[0];
30
31  useEffect(() => {
32    const handleClickOutside = (event: MouseEvent) => {
33      if (
34        dropdownRef.current &&
35        !dropdownRef.current.contains(event.target as Node)
36      ) {
37        setIsOpen(false);
38      }
39    };
40
41    document.addEventListener("mousedown", handleClickOutside);
42    return () => {
43      document.removeEventListener("mousedown", handleClickOutside);
44    };
45  }, []);
46
47  const changeLanguage = (langCode: string) => {
48    const currentPath = window.location.pathname;
49    // Extract the path after the locale segment
50    const pathSegments = currentPath.split('/');
51    pathSegments[1] = langCode; // Replace the locale segment
52    
53    const newPath = pathSegments.join('/');
54    router.push(newPath);
55    setIsOpen(false);
56  };
57
58  return (
59    <div className="relative" ref={dropdownRef}>
60      <button
61        onClick={() => setIsOpen(!isOpen)}
62        className="flex items-center  cursor-pointer px-2 py-2 rounded-md hover:bg-gray-100 dark:hover:bg-gray-800 text-sm"
63        aria-expanded={isOpen}
64        aria-haspopup="true"
65      >
66        <IconLanguage className="w-4 h-4 mr-1" />
67        <span className="font-medium text-xs mr-1">{currentLanguage.code.toUpperCase()}</span>
68        <IconChevronDown className={cn("w-3 h-3 transition-transform", isOpen ? "rotate-180" : "")} />
69      </button>
70
71      {isOpen && (
72        <div className="absolute z-50 mt-1 bg-white dark:bg-neutral-900 border border-gray-200 dark:border-gray-700 rounded-md shadow-lg py-1 w-40 min-w-max right-0">
73          <ul className="py-1">
74            {languages.map((language) => (
75              <li key={language.code}>
76                <button
77                  onClick={() => changeLanguage(language.code)}
78                  className={cn(
79                    "w-full text-left cursor-pointer px-4 py-2 text-sm hover:bg-gray-100 dark:hover:bg-gray-800 flex items-center",
80                    language.code === currentLocale && "bg-gray-100 dark:bg-gray-800"
81                  )}
82                 >
83                  <span className="inline-block me-2 w-max font-medium text-xs">{language.code.toUpperCase()}</span>
84                  {language.name}
85                </button>
86              </li>
87            ))}
88          </ul>
89        </div>
90      )}
91    </div>
92  );
93}