diff --git a/sitemap.php b/sitemap.php
new file mode 100644
index 0000000..c3e3f7f
--- /dev/null
+++ b/sitemap.php
@@ -0,0 +1,109 @@
+<?php
+
+$baseUrl = 'https://miraheze.org';
+$i18nDir = __DIR__ . '/i18n';
+
+if ( !is_dir( $i18nDir ) ) {
+	fwrite( STDERR, "i18n directory not found: $i18nDir\n" );
+	exit( 1 );
+}
+
+$langs = [];
+foreach ( glob( $i18nDir . '/*.json' ) as $path ) {
+	$lang = trim( basename( $path, '.json' ) );
+	if ( $lang === '' || $lang === 'qqq' ) {
+		continue;
+	}
+
+	$langs[] = $lang;
+}
+
+$langs = array_unique( $langs );
+sort( $langs, SORT_STRING );
+
+$toHreflang = static function ( string $tag ): string {
+	$parts = explode( '-', $tag );
+	if ( count( $parts ) === 1 ) {
+		return strtolower( $parts[0] );
+	}
+
+	$out = [];
+	$out[] = strtolower( array_shift( $parts ) );
+
+	foreach ( $parts as $part ) {
+		if ( preg_match( '/^[a-z]{2}$/i', $part ) || preg_match( '/^\d{3}$/', $part ) ) {
+			$out[] = strtoupper( $part );
+			continue;
+		}
+
+		if ( preg_match( '/^[a-z]{4}$/i', $part ) ) {
+			$out[] = strtoupper( $part[0] ) . strtolower( substr( $part, 1 ) );
+			continue;
+		}
+
+		$out[] = strtolower( $part );
+	}
+
+	return implode( '-', $out );
+};
+
+$esc = static fn ( string $s ): string =>
+	htmlspecialchars( $s, ENT_QUOTES | ENT_XML1, 'UTF-8' );
+
+$urls = [
+	[
+		'loc' => $baseUrl . '/',
+		'priority' => '1.0',
+		'changefreq' => 'always',
+	],
+];
+
+foreach ( $langs as $lang ) {
+	$urls[] = [
+		'loc' => $baseUrl . '/' . rawurlencode( $lang ),
+		'priority' => null,
+		'changefreq' => 'weekly',
+	];
+}
+
+$alternates = [
+	[
+		'hreflang' => 'x-default',
+		'href' => $baseUrl . '/',
+	],
+];
+
+foreach ( $langs as $lang ) {
+	$alternates[] = [
+		'hreflang' => $toHreflang( $lang ),
+		'href' => $baseUrl . '/' . rawurlencode( $lang ),
+	];
+}
+
+header( 'Content-Type: application/xml; charset=UTF-8' );
+
+echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
+echo "<urlset xmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\" xmlns:xhtml=\"http://www.w3.org/1999/xhtml\">\n";
+
+foreach ( $urls as $u ) {
+	echo "\t<url>\n";
+	echo "\t\t<loc>" . $esc( $u['loc'] ) . "</loc>\n";
+
+	if ( $u['priority'] !== null ) {
+		echo "\t\t<priority>" . $esc( $u['priority'] ) . "</priority>\n";
+	}
+
+	echo "\t\t<changefreq>" . $esc( $u['changefreq'] ) . "</changefreq>\n";
+
+	foreach ( $alternates as $alt ) {
+		echo "\t\t<xhtml:link rel=\"alternate\" hreflang=\""
+			. $esc( $alt['hreflang'] )
+			. "\" href=\""
+			. $esc( $alt['href'] )
+			. "\" />\n";
+	}
+
+	echo "\t</url>\n";
+}
+
+echo "</urlset>\n";