diff --git a/src/app/duolingo-streak.json b/src/app/duolingo-streak.json
index 32d6838..c489348 100644
--- a/src/app/duolingo-streak.json
+++ b/src/app/duolingo-streak.json
@@ -1,5 +1,5 @@
 {
-  "streak": 1538,
-  "since": "2026-06-14",
+  "streak": 1566,
+  "since": "2026-07-12",
   "username": "marv51"
 }
diff --git a/src/app/routes.ts b/src/app/routes.ts
index 56f4a1d..785d422 100644
--- a/src/app/routes.ts
+++ b/src/app/routes.ts
@@ -5,6 +5,7 @@ export default [
     route("/Project-Quick-Open/datenschutz.html", "routes/project-quick-privacy.tsx"),
     route("/SWR3App/datenschutz.html", "routes/swr3-app-privacy.tsx"),
     route("404", "routes/not-found.tsx", { "index": true}),
+    route("sitemap.xml", "routes/sitemap.tsx"),
     layout("routes/layout.tsx", [
         index("routes/home.tsx"),
         ...prefix("en", [
diff --git a/src/app/routes/home-de.tsx b/src/app/routes/home-de.tsx
index daa5497..266a77e 100644
--- a/src/app/routes/home-de.tsx
+++ b/src/app/routes/home-de.tsx
@@ -1,12 +1,15 @@
 import type { Route } from "./+types/home-de";
 import { Welcome } from "../welcome/welcome";
+import { bilingualLinks, PAGES, SITE_URL } from "../seo-links";
+
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.home, "de");
 
 export function meta({}: Route.MetaArgs) {
   const title = "Marvin Rühe — Teamleitung Softwareentwicklung";
   const description =
     "Marvin Rühe — Teamleitung Softwareentwicklung bei gb&t. Ich entwickle Windows-Apps (WinUI 3, WPF, MSIX), lokale KI und Web-Tools und leite die Entwicklung der preisgekrönten Software telani.";
-  const url = "https://ruehe.me/de";
-  const image = "https://ruehe.me/og-de.jpg";
+  const url = `${SITE_URL}${PAGES.home.de}`;
+  const image = `${SITE_URL}/og-de.jpg`;
   return [
     { title },
     { name: "description", content: description },
diff --git a/src/app/routes/home.tsx b/src/app/routes/home.tsx
index 3e6691c..32caa56 100644
--- a/src/app/routes/home.tsx
+++ b/src/app/routes/home.tsx
@@ -1,12 +1,15 @@
 import type { Route } from "./+types/home";
 import { Welcome } from "../welcome/welcome";
+import { bilingualLinks, PAGES, SITE_URL } from "../seo-links";
+
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.home, "en");
 
 export function meta({}: Route.MetaArgs) {
   const title = "Marvin Rühe — Team Lead, Software Development";
   const description =
     "Marvin Rühe — Team Lead, Software Development at gb&t. I build Windows apps (WinUI 3, WPF, MSIX), on-device AI, and web tools, and lead development of the award-winning telani software.";
-  const url = "https://ruehe.me/";
-  const image = "https://ruehe.me/og.jpg";
+  const url = `${SITE_URL}${PAGES.home.en}`;
+  const image = `${SITE_URL}/og.jpg`;
   return [
     { title },
     { name: "description", content: description },
diff --git a/src/app/routes/imprint-de.tsx b/src/app/routes/imprint-de.tsx
index 7c36a00..ba57442 100644
--- a/src/app/routes/imprint-de.tsx
+++ b/src/app/routes/imprint-de.tsx
@@ -1,10 +1,12 @@
 import type { Route } from "./+types/imprint-de";
 import { Imprint } from "../imprint/imprint";
+import { bilingualLinks, PAGES } from "../seo-links";
+
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.imprint, "de");
 
 export function meta({}: Route.MetaArgs) {
   return [
     { title: "Marvin Rühes Webseite - Impressum und Datenschutz" },
-    { lang: "de" }
   ];
 }
 
diff --git a/src/app/routes/imprint.tsx b/src/app/routes/imprint.tsx
index 30237d4..0c3efc5 100644
--- a/src/app/routes/imprint.tsx
+++ b/src/app/routes/imprint.tsx
@@ -1,10 +1,12 @@
 import type { Route } from "./+types/imprint";
 import { Imprint } from "../imprint/imprint";
+import { bilingualLinks, PAGES } from "../seo-links";
+
+export const links: Route.LinksFunction = () => bilingualLinks(PAGES.imprint, "en");
 
 export function meta({}: Route.MetaArgs) {
   return [
     { title: "Marvin Rühe's Webseite - Imprint & Privacy" },
-    { lang: "en" }
   ];
 }
 
diff --git a/src/app/routes/layout-de.tsx b/src/app/routes/layout-de.tsx
index b9cb677..fd15d7e 100644
--- a/src/app/routes/layout-de.tsx
+++ b/src/app/routes/layout-de.tsx
@@ -6,7 +6,6 @@ import { Footer } from "../footer/footer";
 export function meta({}: Route.MetaArgs) {
   return [
     { title: "Marvin Rühe's Webseite" },
-    { lang: "en" }
   ];
 }
 
diff --git a/src/app/routes/layout.tsx b/src/app/routes/layout.tsx
index 7045409..152a5ce 100644
--- a/src/app/routes/layout.tsx
+++ b/src/app/routes/layout.tsx
@@ -6,7 +6,6 @@ import { Footer } from "../footer/footer";
 export function meta({}: Route.MetaArgs) {
   return [
     { title: "Marvin Rühe's Webseite" },
-    { lang: "en" }
   ];
 }
 
diff --git a/src/app/routes/sitemap.tsx b/src/app/routes/sitemap.tsx
new file mode 100644
index 0000000..0508587
--- /dev/null
+++ b/src/app/routes/sitemap.tsx
@@ -0,0 +1,9 @@
+import { renderSitemap } from "../seo-links";
+
+// Resource route (loader only, no component): prerendered to
+// build/client/sitemap.xml, and also served live under `npm run dev`.
+export function loader() {
+  return new Response(renderSitemap(), {
+    headers: { "Content-Type": "application/xml" },
+  });
+}
diff --git a/src/app/seo-links.ts b/src/app/seo-links.ts
new file mode 100644
index 0000000..063ed6a
--- /dev/null
+++ b/src/app/seo-links.ts
@@ -0,0 +1,52 @@
+export const SITE_URL = "https://ruehe.me";
+
+export type Lang = "en" | "de";
+export type PagePair = { en: string; de: string };
+
+/**
+ * EN ↔ DE equivalents for every indexable page. Single source of truth: per-page
+ * canonical/hreflang links (`bilingualLinks`) and the generated sitemap
+ * (`renderSitemap`) both read from this, so a new page added here flows to both.
+ */
+export const PAGES = {
+  home: { en: "/", de: "/de" },
+  imprint: { en: "/en/imprint", de: "/de/impressum" },
+} as const satisfies Record<string, PagePair>;
+
+/** Canonical + hreflang alternate <link>s for one page in one language. */
+export function bilingualLinks({ en, de }: PagePair, current: Lang) {
+  return [
+    { rel: "canonical", href: `${SITE_URL}${current === "en" ? en : de}` },
+    { rel: "alternate", hrefLang: "en", href: `${SITE_URL}${en}` },
+    { rel: "alternate", hrefLang: "de", href: `${SITE_URL}${de}` },
+    { rel: "alternate", hrefLang: "x-default", href: `${SITE_URL}${en}` },
+  ];
+}
+
+/** The sitemap.xml document, derived from PAGES. */
+export function renderSitemap(): string {
+  const urls = Object.values(PAGES)
+    .flatMap(({ en, de }) =>
+      [en, de].map(
+        (loc) => `  <url>
+    <loc>${SITE_URL}${loc}</loc>
+    <xhtml:link rel="alternate" hreflang="en" href="${SITE_URL}${en}" />
+    <xhtml:link rel="alternate" hreflang="de" href="${SITE_URL}${de}" />
+    <xhtml:link rel="alternate" hreflang="x-default" href="${SITE_URL}${en}" />
+  </url>`,
+      ),
+    )
+    .join("\n");
+
+  return `<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+        xmlns:xhtml="http://www.w3.org/1999/xhtml">
+${urls}
+</urlset>
+`;
+}
+
+/** Every URL listed in the sitemap (both languages), for build-time drift checks. */
+export function sitemapPaths(): string[] {
+  return Object.values(PAGES).flatMap(({ en, de }) => [en, de]);
+}
diff --git a/src/public/robots.txt b/src/public/robots.txt
new file mode 100644
index 0000000..b6034e7
--- /dev/null
+++ b/src/public/robots.txt
@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://ruehe.me/sitemap.xml
diff --git a/src/react-router.config.ts b/src/react-router.config.ts
index e9758ea..f32a97a 100644
--- a/src/react-router.config.ts
+++ b/src/react-router.config.ts
@@ -1,8 +1,33 @@
 import type { Config } from "@react-router/dev/config";
+import { sitemapPaths } from "./app/seo-links";
+
+// Prerendered paths intentionally kept OUT of the sitemap: the error page, the
+// sitemap resource route itself, and the two standalone app privacy policies
+// (not part of the bilingual site).
+const SITEMAP_EXCLUDED = new Set([
+  "/404",
+  "/sitemap.xml",
+  "/Project-Quick-Open/datenschutz.html",
+  "/SWR3App/datenschutz.html",
+]);
 
 export default {
-  // Config options...
-  // Server-side render by default, to enable SPA mode set this to `false`
   ssr: false,
-  prerender: true,
+  // Function form of `prerender` returns the same static paths as `true`, but
+  // also lets us cross-check route discovery against the sitemap. A prerendered
+  // page missing from both PAGES and the exclude list fails the build, so the
+  // sitemap can't silently fall out of sync with the routes.
+  prerender: ({ getStaticPaths }) => {
+    const discovered = getStaticPaths();
+    const known = new Set([...sitemapPaths(), ...SITEMAP_EXCLUDED]);
+    const unaccounted = discovered.filter((path) => !known.has(path));
+    if (unaccounted.length > 0) {
+      throw new Error(
+        `[sitemap] Prerendered path(s) missing from the sitemap and exclude ` +
+          `list: ${unaccounted.join(", ")}. Add them to PAGES in ` +
+          `app/seo-links.ts, or to SITEMAP_EXCLUDED in react-router.config.ts.`,
+      );
+    }
+    return discovered;
+  },
 } satisfies Config;