diff --git a/package.json b/package.json
index db12cc4c..984e8b76 100644
--- a/package.json
+++ b/package.json
@@ -9,9 +9,10 @@
     "prepare:assets": "npm run prepare:sprites && npm run prepare:style",
     "check:export": "node scripts/check-export.mjs",
     "check:runtime": "node scripts/check-runtime.mjs && node scripts/validate-maplibre-style.mjs && node scripts/check-globe-parity.mjs && node scripts/check-cartography-parity.mjs && node scripts/check-viewer-quality.mjs && node scripts/check-photo-reference.mjs",
+    "check:server": "node scripts/check-server-health.mjs",
     "check": "npm run check:export && npm run check:runtime",
     "dev": "npm run prepare:assets && vite",
-    "build": "npm run prepare:assets && npm run check && vite build",
+    "build": "npm run prepare:assets && npm run check && vite build && npm run check:server",
     "preview": "vite preview",
     "start": "node server.mjs"
   },
diff --git a/scripts/check-server-health.mjs b/scripts/check-server-health.mjs
new file mode 100644
index 00000000..b4d487f5
--- /dev/null
+++ b/scripts/check-server-health.mjs
@@ -0,0 +1,72 @@
+import { spawn } from 'node:child_process';
+import { once } from 'node:events';
+import http from 'node:http';
+
+const port = 43173;
+const child = spawn(process.execPath, ['server.mjs'], {
+  env: { ...process.env, PORT: String(port), HOST: '0.0.0.0' },
+  stdio: ['ignore', 'pipe', 'pipe']
+});
+
+let output = '';
+child.stdout.on('data', (chunk) => {
+  output += chunk.toString();
+});
+child.stderr.on('data', (chunk) => {
+  output += chunk.toString();
+});
+
+async function request(method) {
+  return new Promise((resolve, reject) => {
+    const req = http.request(
+      {
+        hostname: '127.0.0.1',
+        port,
+        path: '/health?render-probe=1',
+        method,
+        timeout: 3000,
+        headers: { Host: `map-yxjb.onrender.com:${port}` }
+      },
+      (response) => {
+        let body = '';
+        response.setEncoding('utf8');
+        response.on('data', (chunk) => {
+          body += chunk;
+        });
+        response.on('end', () => resolve({ status: response.statusCode, body }));
+      }
+    );
+    req.on('timeout', () => req.destroy(new Error(`${method} /health timed out`)));
+    req.on('error', reject);
+    req.end();
+  });
+}
+
+try {
+  const deadline = Date.now() + 8000;
+  while (!output.includes('Health endpoint ready')) {
+    if (child.exitCode !== null) throw new Error(`Server exited early with code ${child.exitCode}.\n${output}`);
+    if (Date.now() > deadline) throw new Error(`Server did not become ready.\n${output}`);
+    await new Promise((resolve) => setTimeout(resolve, 100));
+  }
+
+  const get = await request('GET');
+  if (get.status !== 200 || get.body !== 'ok') {
+    throw new Error(`GET /health returned ${get.status} with body ${JSON.stringify(get.body)}`);
+  }
+
+  const head = await request('HEAD');
+  if (head.status !== 200 || head.body !== '') {
+    throw new Error(`HEAD /health returned ${head.status} with body ${JSON.stringify(head.body)}`);
+  }
+
+  console.log('Server health check passed for GET and HEAD with a Render-style Host header.');
+} finally {
+  child.kill('SIGTERM');
+  if (child.exitCode === null) {
+    await Promise.race([
+      once(child, 'exit'),
+      new Promise((resolve) => setTimeout(resolve, 2000))
+    ]);
+  }
+}
diff --git a/server.mjs b/server.mjs
index 26e04ff3..5e3c6bcc 100644
--- a/server.mjs
+++ b/server.mjs
@@ -5,6 +5,7 @@ import { fileURLToPath } from 'node:url';
 
 const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), 'dist');
 const port = Number(process.env.PORT || 4173);
+const host = process.env.HOST?.trim() || '0.0.0.0';
 
 const contentTypes = {
   '.css': 'text/css; charset=utf-8',
@@ -25,11 +26,11 @@ function requestOrigin(request) {
   const forwardedProtocol = String(request.headers['x-forwarded-proto'] || '').split(',')[0].trim();
   const forwardedHost = String(request.headers['x-forwarded-host'] || '').split(',')[0].trim();
   const protocol = forwardedProtocol || 'http';
-  const host = forwardedHost || request.headers.host || `localhost:${port}`;
-  return `${protocol}://${host}`;
+  const requestHost = forwardedHost || request.headers.host || `localhost:${port}`;
+  return `${protocol}://${requestHost}`;
 }
 
-function send(response, status, body, contentType, cacheControl = 'no-store') {
+function send(response, status, body, contentType, cacheControl = 'no-store', method = 'GET') {
   response.writeHead(status, {
     'Access-Control-Allow-Origin': '*',
     'Access-Control-Allow-Methods': 'GET, HEAD, OPTIONS',
@@ -41,7 +42,20 @@ function send(response, status, body, contentType, cacheControl = 'no-store') {
     'Cross-Origin-Resource-Policy': 'cross-origin',
     'X-Content-Type-Options': 'nosniff'
   });
-  if (response.req.method === 'HEAD') response.end();
+  if (method === 'HEAD') response.end();
+  else response.end(body);
+}
+
+function sendHealth(request, response) {
+  const body = 'ok';
+  response.statusCode = 200;
+  response.shouldKeepAlive = false;
+  response.setHeader('Content-Type', 'text/plain; charset=utf-8');
+  response.setHeader('Content-Length', Buffer.byteLength(body));
+  response.setHeader('Cache-Control', 'no-store');
+  response.setHeader('Connection', 'close');
+  response.setHeader('X-Content-Type-Options', 'nosniff');
+  if (request.method === 'HEAD') response.end();
   else response.end(body);
 }
 
@@ -54,7 +68,8 @@ async function serveStyle(request, response) {
     200,
     resolved,
     contentTypes['.json'],
-    'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0'
+    'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0',
+    request.method
   );
 }
 
@@ -64,7 +79,7 @@ async function serveStatic(request, response, pathname) {
   const absolute = path.resolve(root, `.${decoded}`);
 
   if (!absolute.startsWith(`${root}${path.sep}`) && absolute !== path.join(root, 'index.html')) {
-    send(response, 403, 'Forbidden', 'text/plain; charset=utf-8');
+    send(response, 403, 'Forbidden', 'text/plain; charset=utf-8', 'no-store', request.method);
     return;
   }
 
@@ -79,57 +94,88 @@ async function serveStatic(request, response, pathname) {
       200,
       body,
       contentTypes[extension] || 'application/octet-stream',
-      longLived ? 'public, max-age=31536000, immutable' : 'no-store, no-cache, must-revalidate, max-age=0'
+      longLived ? 'public, max-age=31536000, immutable' : 'no-store, no-cache, must-revalidate, max-age=0',
+      request.method
     );
   } catch {
     const index = await fs.readFile(path.join(root, 'index.html'));
-    send(response, 200, index, contentTypes['.html'], 'no-store, no-cache, must-revalidate, max-age=0');
+    send(
+      response,
+      200,
+      index,
+      contentTypes['.html'],
+      'no-store, no-cache, must-revalidate, max-age=0',
+      request.method
+    );
   }
 }
 
-const server = http.createServer(async (request, response) => {
-  try {
-    if (request.method === 'OPTIONS') {
-      response.writeHead(204, {
-        'Access-Control-Allow-Origin': '*',
-        'Access-Control-Allow-Methods': 'GET, HEAD, OPTIONS',
-        'Access-Control-Allow-Headers': 'Content-Type, Cache-Control, Pragma',
-        'Cache-Control': 'no-store'
-      });
-      response.end();
-      return;
-    }
+async function handleRequest(request, response) {
+  const method = request.method || 'GET';
+
+  if (method === 'OPTIONS') {
+    response.writeHead(204, {
+      'Access-Control-Allow-Origin': '*',
+      'Access-Control-Allow-Methods': 'GET, HEAD, OPTIONS',
+      'Access-Control-Allow-Headers': 'Content-Type, Cache-Control, Pragma',
+      'Cache-Control': 'no-store'
+    });
+    response.end();
+    return;
+  }
 
-    if (!['GET', 'HEAD'].includes(request.method || '')) {
-      send(response, 405, 'Method not allowed', 'text/plain; charset=utf-8');
-      return;
-    }
+  if (!['GET', 'HEAD'].includes(method)) {
+    send(response, 405, 'Method not allowed', 'text/plain; charset=utf-8', 'no-store', method);
+    return;
+  }
 
-    const url = new URL(request.url || '/', `http://${request.headers.host || 'localhost'}`);
+  const url = new URL(request.url || '/', `http://${request.headers.host || 'localhost'}`);
 
-    if (url.pathname === '/health') {
+  if (url.pathname === '/style/occumed-open.json') {
+    await serveStyle(request, response);
+    return;
+  }
+
+  await serveStatic(request, response, url.pathname);
+}
+
+const server = http.createServer((request, response) => {
+  const rawPath = (request.url || '/').split('?', 1)[0];
+
+  // Keep Render's deployment probe completely independent from URL parsing,
+  // filesystem access, the built map assets, and all application routing.
+  if (rawPath === '/health' || rawPath === '/healthz') {
+    sendHealth(request, response);
+    return;
+  }
+
+  void handleRequest(request, response).catch((error) => {
+    console.error(error);
+    if (!response.headersSent) {
       send(
         response,
-        200,
-        JSON.stringify({ ok: true, service: 'occumed-map' }),
-        contentTypes['.json'],
-        'no-store'
+        500,
+        'Internal server error',
+        'text/plain; charset=utf-8',
+        'no-store',
+        request.method
       );
-      return;
+    } else {
+      response.destroy();
     }
+  });
+});
 
-    if (url.pathname === '/style/occumed-open.json') {
-      await serveStyle(request, response);
-      return;
-    }
+server.requestTimeout = 30_000;
+server.headersTimeout = 35_000;
+server.keepAliveTimeout = 5_000;
 
-    await serveStatic(request, response, url.pathname);
-  } catch (error) {
-    console.error(error);
-    send(response, 500, 'Internal server error', 'text/plain; charset=utf-8');
-  }
+server.on('error', (error) => {
+  console.error('Occu-Med Map server error:', error);
+  process.exitCode = 1;
 });
 
-server.listen(port, '0.0.0.0', () => {
-  console.log(`Occu-Med Map listening on port ${port}.`);
+server.listen(port, host, () => {
+  console.log(`Occu-Med Map listening on ${host}:${port}.`);
+  console.log(`Health endpoint ready at http://127.0.0.1:${port}/health.`);
 });