diff --git a/.env.example b/.env.example
index efef8c1..d9967c5 100644
--- a/.env.example
+++ b/.env.example
@@ -1,3 +1,6 @@
+# Public site origin used for SEO metadata, sitemap, and robots.txt.
+BASE_URL=https://guide.sudloh.com
+
 # Local-only demo mode serves sanitized fixtures and bypasses external services.
 # Keep this false in every deployed environment.
 BUZZ_DEMO_MODE=false
diff --git a/app/layout.tsx b/app/layout.tsx
index e2a20f3..5f9006f 100644
--- a/app/layout.tsx
+++ b/app/layout.tsx
@@ -4,6 +4,7 @@ import { Anuphan, Geist_Mono } from "next/font/google";
 import { DeploymentUpdateNotifier } from "@/components/deployment-update-notifier";
 import { PageProgress } from "@/components/page-progress";
 import { Toaster } from "@/components/ui/sonner";
+import { siteUrl } from "@/lib/site-url";
 
 import "./globals.css";
 
@@ -19,12 +20,13 @@ const geistMono = Geist_Mono({
 });
 
 export const metadata: Metadata = {
-  metadataBase: new URL("https://guide.sudloh.com"),
+  metadataBase: new URL(siteUrl),
   title: {
     default: "Buzz Guide",
     template: "%s",
   },
   description: "ไกด์ตัวละครจากช่องเกนชินไม่ใช่เกมมือถือ",
+  keywords: ["เกนชิน", "เกนชินไม่ใช่เกมมือถือ", "Buzz", "ไกด์", "สุดหล่อ"],
 };
 
 export default function RootLayout({ children }: LayoutProps<"/">) {
diff --git a/app/robots.ts b/app/robots.ts
index 9398ddc..96aa6f5 100644
--- a/app/robots.ts
+++ b/app/robots.ts
@@ -1,5 +1,7 @@
 import type { MetadataRoute } from "next";
 
+import { siteUrl } from "@/lib/site-url";
+
 export default function robots(): MetadataRoute.Robots {
   return {
     rules: {
@@ -7,5 +9,6 @@ export default function robots(): MetadataRoute.Robots {
       allow: "/",
       disallow: ["/admin", "/api", "/register"],
     },
+    sitemap: `${siteUrl}/sitemap.xml`,
   };
 }
diff --git a/app/sitemap.ts b/app/sitemap.ts
new file mode 100644
index 0000000..9f0bcb1
--- /dev/null
+++ b/app/sitemap.ts
@@ -0,0 +1,17 @@
+import type { MetadataRoute } from "next";
+import { connection } from "next/server";
+
+import { getCachedPublicGuideCards } from "@/lib/cache/public";
+import { siteUrl } from "@/lib/site-url";
+
+export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
+  await connection();
+  const guides = await getCachedPublicGuideCards();
+
+  return [
+    { url: siteUrl },
+    ...guides.map((guide) => ({
+      url: `${siteUrl}/${encodeURIComponent(guide.slug)}`,
+    })),
+  ];
+}
diff --git a/lib/site-url.ts b/lib/site-url.ts
new file mode 100644
index 0000000..c39f5bd
--- /dev/null
+++ b/lib/site-url.ts
@@ -0,0 +1,7 @@
+const configuredBaseUrl = process.env.BASE_URL?.trim();
+
+if (!configuredBaseUrl) {
+  throw new Error("BASE_URL is required for site metadata and sitemaps.");
+}
+
+export const siteUrl = new URL(configuredBaseUrl).origin;