diff --git a/app/core/Maintenance.php b/app/core/Maintenance.php
new file mode 100644
index 0000000..253f9db
--- /dev/null
+++ b/app/core/Maintenance.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace App\Core;
+
+class Maintenance
+{
+    public const FLAG_PATH = __DIR__ . '/../../storage/maintenance.flag';
+
+    public static function isEnabled(): bool
+    {
+        return file_exists(self::FLAG_PATH);
+    }
+
+    public static function enable(string $message = ''): bool
+    {
+        $dir = dirname(self::FLAG_PATH);
+        if (!is_dir($dir)) {
+            mkdir($dir, 0755, true);
+        }
+        $content = $message !== '' ? $message : 'Site is under maintenance';
+        return file_put_contents(self::FLAG_PATH, $content) !== false;
+    }
+
+    public static function disable(): bool
+    {
+        if (file_exists(self::FLAG_PATH)) {
+            return unlink(self::FLAG_PATH);
+        }
+        return true;
+    }
+
+    public static function getMessage(): string
+    {
+        if (!self::isEnabled()) {
+            return '';
+        }
+        $msg = @file_get_contents(self::FLAG_PATH);
+        return is_string($msg) ? trim($msg) : '';
+    }
+}
diff --git a/app/templates/maintenance.php b/app/templates/maintenance.php
new file mode 100644
index 0000000..9828a24
--- /dev/null
+++ b/app/templates/maintenance.php
@@ -0,0 +1,20 @@
+<?php
+/**
+ * Maintenance mode page
+ */
+?>
+<div class="container mt-5">
+    <div class="row justify-content-center">
+        <div class="col-md-8">
+            <div class="card border-warning">
+                <div class="card-header bg-warning text-dark">
+                    <strong>Maintenance mode</strong>
+                </div>
+                <div class="card-body">
+                    <p class="lead">The site is temporarily unavailable due to maintenance.</p>
+                    <p class="text-muted">Please try again later.</p>
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
diff --git a/doc/database/README.md b/doc/database/README.md
index 87e0a24..2bbc03a 100644
--- a/doc/database/README.md
+++ b/doc/database/README.md
@@ -26,11 +26,29 @@ php scripts/migrate.php up
 3. Typical deployment steps
 
 - Pull new code from git.
-- Put the site in maintenance mode (optional, recommended for sensitive changes).
+- Put the site in maintenance mode (recommended): `php scripts/maintenance.php on "Upgrading database"`.
 - Run `php scripts/migrate.php status`.
 - If there are pending migrations, run `php scripts/migrate.php up`.
+- Disable maintenance mode: `php scripts/maintenance.php off`.
 - Clear opcache if applicable and resume traffic.
 
+## Maintenance mode
+
+Enable maintenance mode to temporarily block non-admin traffic during upgrades. Superusers (user ID 1 or with `superuser` right) can still access the site.
+
+Commands:
+
+```bash
+# Turn on with optional message
+php scripts/maintenance.php on "Upgrading database"
+
+# Turn off
+php scripts/maintenance.php off
+
+# Status
+php scripts/maintenance.php status
+```
+
 ## Authoring new migrations
 
 1. Create a new SQL file in `doc/database/migrations/`, e.g.:
diff --git a/public_html/index.php b/public_html/index.php
index 771c7bf..d69559b 100644
--- a/public_html/index.php
+++ b/public_html/index.php
@@ -229,6 +229,30 @@ if (!$pipeline->run()) {
     exit;
 }
 
+// Maintenance mode: show maintenance page to non-superusers
+try {
+    require_once __DIR__ . '/../app/core/Maintenance.php';
+    if (\App\Core\Maintenance::isEnabled()) {
+        $isSuperuser = false;
+        if ($validSession && isset($userId) && isset($userObject) && method_exists($userObject, 'hasRight')) {
+            // user 1 is always superuser per implementation, but also check explicit right
+            $isSuperuser = ($userId === 1) || (bool)$userObject->hasRight($userId, 'superuser');
+        }
+        if (!$isSuperuser) {
+            http_response_code(503);
+            // Show themed maintenance page
+            \App\Helpers\Theme::include('page-header');
+            \App\Helpers\Theme::include('page-menu');
+            include __DIR__ . '/../app/templates/maintenance.php';
+            \App\Helpers\Theme::include('page-footer');
+            ob_end_flush();
+            exit;
+        }
+    }
+} catch (\Throwable $e) {
+    // Do not break app if maintenance check fails
+}
+
 // Apply per-user theme from DB into session (without persisting) once user is known
 if ($validSession && isset($userId) && isset($userObject) && is_object($userObject) && method_exists($userObject, 'getUserTheme')) {
     try {
diff --git a/scripts/maintenance.php b/scripts/maintenance.php
new file mode 100644
index 0000000..ce58c89
--- /dev/null
+++ b/scripts/maintenance.php
@@ -0,0 +1,49 @@
+#!/usr/bin/env php
+<?php
+
+require_once __DIR__ . '/../app/core/Maintenance.php';
+
+use App\Core\Maintenance;
+
+function usage()
+{
+    echo "\nJilo Web - Maintenance Mode\n";
+    echo "Usage:\n";
+    echo "  php scripts/maintenance.php on  [message]  # Enable maintenance mode with optional message\n";
+    echo "  php scripts/maintenance.php off           # Disable maintenance mode\n";
+    echo "  php scripts/maintenance.php status        # Show maintenance status\n\n";
+}
+
+$cmd = $argv[1] ?? 'status';
+
+try {
+    switch ($cmd) {
+        case 'on':
+            $message = $argv[2] ?? '';
+            if (Maintenance::enable($message)) {
+                echo "Maintenance mode ENABLED" . ($message ? ": $message" : '') . "\n";
+                exit(0);
+            }
+            fwrite(STDERR, "Failed to enable maintenance mode\n");
+            exit(1);
+        case 'off':
+            if (Maintenance::disable()) {
+                echo "Maintenance mode DISABLED\n";
+                exit(0);
+            }
+            fwrite(STDERR, "Failed to disable maintenance mode\n");
+            exit(1);
+        case 'status':
+        default:
+            if (Maintenance::isEnabled()) {
+                $msg = Maintenance::getMessage();
+                echo "Maintenance: ON" . ($msg ? " - $msg" : '') . "\n";
+            } else {
+                echo "Maintenance: OFF\n";
+            }
+            exit(0);
+    }
+} catch (Throwable $e) {
+    fwrite(STDERR, "Error: " . $e->getMessage() . "\n");
+    exit(1);
+}