```bash
.
├── locales
│ ├── en
│ │ ├── common.json
│ │ └── about.json
│ ├── fr
│ │ ├── common.json
│ │ └── about.json
│ └── es
│ ├── common.json
│ └── about.json
└── src
├── i18n.ts
├── middleware.ts
├── app
│ └── [locale]
│ ├── layout.tsx
│ └── about
│ └── page.tsx
└── components
├── ClientComponentExample.tsx
└── ServerComponent.tsx
```
#### Setup and Loading Content
As mentioned previously, you must optimize how each JSON file is imported into your code.
How the library handles content loading is important.
```tsx fileName="src/i18n.ts"
import { getRequestConfig } from "next-intl/server";
import { notFound } from "next/navigation";
export const locales = ["en", "fr", "es"] as const;
export const defaultLocale = "en" as const;
async function loadMessages(locale: string) {
// Load only the namespaces your layout/pages need
const [common, about] = await Promise.all([
import(`../locales/${locale}/common.json`).then((m) => m.default),
import(`../locales/${locale}/about.json`).then((m) => m.default),
]);
return { common, about } as const;
}
export default getRequestConfig(async ({ locale }) => {
if (!locales.includes(locale as any)) notFound();
return {
messages: await loadMessages(locale),
};
});
```
```tsx fileName="src/app/[locale]/layout.tsx"
import type { ReactNode } from "react";
import { locales } from "@/i18n";
import {
getLocaleDirection,
unstable_setRequestLocale,
} from "next-intl/server";
export function generateStaticParams() {
return locales.map((locale) => ({ locale }));
}
export default function LocaleLayout({
children,
params,
}: {
children: ReactNode;
params: Promise<{ locale: string }>;
}) {
const { locale } = await params;
// Set the active request locale for this server render (RSC)
unstable_setRequestLocale(locale);
const dir = getLocaleDirection(locale);
return (
<html lang={locale} dir={dir}>
<body>{children}</body>
</html>
);
}
```
```tsx fileName="src/app/[locale]/about/page.tsx"
import { getTranslations, getMessages, getFormatter } from "next-intl/server";
import { NextIntlClientProvider } from "next-intl";
import pick from "lodash/pick";
import ServerComponent from "@/components/ServerComponent";
import ClientComponentExample from "@/components/ClientComponentExample";
export default async function AboutPage({
params,
}: {
params: Promise<{ locale: string }>;
}) {
const { locale } = await params;
// Messages are loaded server-side. Push only what's needed to the client.
const messages = await getMessages();
const clientMessages = pick(messages, ["common", "about"]);
// Strictly server-side translations/formatting
const tAbout = await getTranslations("about");
const tCounter = await getTranslations("about.counter");
const format = await getFormatter();
const initialFormattedCount = format.number(0);
return (
<NextIntlClientProvider locale={locale} messages={clientMessages}>
<main>
<h1>{tAbout("title")}</h1>
<ClientComponentExample />
<ServerComponent
formattedCount={initialFormattedCount}
label={tCounter("label")}
increment={tCounter("increment")}
/>
</main>
</NextIntlClientProvider>
);
}
```
### Usage in a client component
Let's take an example of a client component rendering a counter.
**Translations (shape reused; load them into next-intl messages as you prefer)**
```json fileName="locales/en/about.json"
{
"counter": {
"label": "Counter",
"increment": "Increment"
}
}
```
```json fileName="locales/fr/about.json"
{
"counter": {
"label": "Compteur",
"increment": "Incrémenter"
}
}
```
**Client component**
```tsx fileName="src/components/ClientComponentExample.tsx"
"use client";
import React, { useState } from "react";
import { useTranslations, useFormatter } from "next-intl";
const ClientComponentExample = () => {
// Scope directly to the nested object
const t = useTranslations("about.counter");
const format = useFormatter();
const [count, setCount] = useState(0);
return (
<div>
<p>{format.number(count)}</p>
<button
aria-label={t("label")}
onClick={() => setCount((count) => count + 1)}
>
{t("increment")}
</button>
</div>
);
};
```
> Don't forget to add "about" message on the page client message
> (only include the namespaces your client actually needs).
### Usage in a server component
We will take the case of a UI component. This component is a server component, and should be able to be inserted as a child of a client component. (page (server component) -> client component -> server component). As this component can be inserted as a child of a client component, it cannot be async.
```tsx fileName="src/components/ServerComponent.tsx"
type ServerComponentProps = {
count: number;
t: (key: string) => string;
formatter: Intl.NumberFormat;
};
const ServerComponent = ({ t, count, formatter }: ServerComponentProps) => {
const formatted = formatter.format(count);
return (
<div>
<p>{formatted}</p>
<button aria-label={t("label")}>{t("increment")}</button>
</div>
);
};
```
> As the server component cannot be async, you need to pass the translations and formatter function as props.
>
> In your page / layout:
>
> - `import { getTranslations, getFormatter } from "next-intl/server";`
> - `const t = await getTranslations("about.counter");`
> - `const formatter = await getFormatter().then((formatter) => formatter.number());`
```tsx fileName="src/app/[locale]/about/layout.tsx"
import type { Metadata } from "next";
import { locales, defaultLocale } from "@/i18n";
import { getTranslations } from "next-intl/server";
function localizedPath(locale: string, path: string) {
return locale === defaultLocale ? path : "/" + locale + path;
}
export async function generateMetadata({
params,
}: {
params: { locale: string };
}): Promise<Metadata> {
const { locale } = params;
const t = await getTranslations({ locale, namespace: "about" });
const url = "/about";
const languages = Object.fromEntries(
locales.map((locale) => [locale, localizedPath(locale, url)])
);
return {
title: t("title"),
description: t("description"),
alternates: {
canonical: localizedPath(locale, url),
languages: { ...languages, "x-default": url },
},
};
}
// ... Rest of the page code
```
```tsx fileName="src/app/sitemap.ts"
import type { MetadataRoute } from "next";
import { locales, defaultLocale } from "@/i18n";
const origin = "https://example.com";
const formatterLocalizedPath = (locale: string, path: string) =>
locale === defaultLocale ? origin + path : origin + "/" + locale + path;
export default function sitemap(): MetadataRoute.Sitemap {
const aboutLanguages = Object.fromEntries(
locales.map((l) => [l, formatterLocalizedPath(l, "/about")])
);
return [
{
url: formatterLocalizedPath(defaultLocale, "/about"),
lastModified: new Date(),
changeFrequency: "monthly",
priority: 0.7,
alternates: { languages: aboutLanguages },
},
];
}
```
```tsx fileName="src/app/robots.ts"
import type { MetadataRoute } from "next";
import { locales, defaultLocale } from "@/i18n";
const origin = "https://example.com";
const withAllLocales = (path: string) => [
path,
...locales
.filter((locale) => locale !== defaultLocale)
.map((locale) => "/" + locale + path),
];
export default function robots(): MetadataRoute.Robots {
const disallow = [
...withAllLocales("/dashboard"),
...withAllLocales("/admin"),
];
return {
rules: { userAgent: "*", allow: ["/"], disallow },
host: origin,
sitemap: origin + "/sitemap.xml",
};
}
```
### Middleware for locale routing
Add a middleware to handle locale detection and routing:
```ts fileName="src/middleware.ts"
import createMiddleware from "next-intl/middleware";
import { locales, defaultLocale } from "@/i18n";
export default createMiddleware({
locales: [...locales],
defaultLocale,
localeDetection: true,
});
export const config = {
// Skip API, Next internals and static assets
matcher: ["/((?!api|_next|.*\\..*).*)"],
};
```
### Best practices
- **Set html `lang` and `dir`**: In `src/app/[locale]/layout.tsx`, compute `dir` via `getLocaleDirection(locale)` and set `<html lang={locale} dir={dir}>`.
- **Split messages by namespace**: Organize JSON per locale and namespace (e.g., `common.json`, `about.json`).
- **Minimize client payload**: On pages, send only required namespaces to `NextIntlClientProvider` (e.g., `pick(messages, ['common', 'about'])`).
- **Prefer static pages**: Export `export const dynamic = 'force-static'` and generate static params for all `locales`.
- **Synchronous server components**: Keep server components sync by passing precomputed strings (translated labels, formatted numbers) rather than async calls or non-serializable functions.
