diff --git a/include/nc_connector_ws.inc.php b/include/nc_connector_ws.inc.php
new file mode 100644
index 0000000..c286b87
--- /dev/null
+++ b/include/nc_connector_ws.inc.php
@@ -0,0 +1,123 @@
+<?php
+if (!defined('PHPWG_ROOT_PATH'))
+{
+  die('Hacking attempt!');
+}
+
+/**
+ * Registers the connector-owned filesystem synchronization endpoint.
+ *
+ * Authentication and authorization are delegated to Piwigo's Web API.
+ * The method is administrator-only and POST-only so an API key inherits the
+ * permissions of its Piwigo user without storing that user's password.
+ */
+function bratonien_tools_register_ws_methods($arr)
+{
+  $service = &$arr[0];
+
+  $service->addMethod(
+    'bratonien.nc.sync',
+    'bratonien_tools_ws_nc_sync',
+    array(
+      'site_id' => array(
+        'default' => 1,
+        'type' => WS_TYPE_ID,
+        'info' => 'Piwigo storage site to synchronize. Default: 1.',
+      ),
+    ),
+    'Synchronizes a local Piwigo filesystem site for the Bratonien NC Connector.',
+    null,
+    array(
+      'admin_only' => true,
+      'post_only' => true,
+    )
+  );
+}
+
+/**
+ * Runs the same local filesystem synchronization currently used by Piwigo's
+ * admin site_update page, but inside an authenticated Web API request.
+ */
+function bratonien_tools_ws_nc_sync($params, &$service)
+{
+  global $conf, $template, $page, $user;
+
+  if (empty($conf['enable_synchronization']))
+  {
+    return new PwgError(403, 'Piwigo filesystem synchronization is disabled.');
+  }
+
+  $site_id = isset($params['site_id']) ? (int)$params['site_id'] : 1;
+  if ($site_id < 1)
+  {
+    return new PwgError(400, 'Invalid site_id.');
+  }
+
+  $query = '\nSELECT galleries_url\n  FROM '.SITES_TABLE.'\n  WHERE id = '.$site_id.'\n  LIMIT 1';
+  $result = pwg_query($query);
+  if (!pwg_db_num_rows($result))
+  {
+    return new PwgError(404, 'Piwigo site does not exist.');
+  }
+
+  list($site_url) = pwg_db_fetch_row($result);
+  if (url_is_remote($site_url))
+  {
+    return new PwgError(400, 'Remote Piwigo sites are not supported by this synchronization method.');
+  }
+
+  $saved_get = $_GET;
+  $saved_post = $_POST;
+
+  $_GET['site'] = (string)$site_id;
+  $_POST = array(
+    'sync' => 'files',
+    'display_info' => '1',
+    'privacy_level' => '0',
+    'sync_meta' => '1',
+    'simulate' => '0',
+    'subcats-included' => '1',
+    'submit' => '1',
+  );
+
+  $counts = array();
+  $errors = array();
+  $infos = array();
+  $general_failure = true;
+
+  try
+  {
+    ob_start();
+    include(PHPWG_ROOT_PATH.'admin/site_update.php');
+    ob_end_clean();
+  }
+  catch (Throwable $e)
+  {
+    if (ob_get_level() > 0)
+    {
+      ob_end_clean();
+    }
+    $_GET = $saved_get;
+    $_POST = $saved_post;
+    return new PwgError(500, 'Piwigo synchronization failed: '.$e->getMessage());
+  }
+
+  $_GET = $saved_get;
+  $_POST = $saved_post;
+
+  if ($general_failure)
+  {
+    return new PwgError(500, 'Piwigo could not open the configured local site.');
+  }
+
+  return array(
+    'site_id' => $site_id,
+    'site_url' => $site_url,
+    'counts' => $counts,
+    'errors' => $errors,
+    'info_count' => count($infos),
+    'connected_with' => isset($_SESSION['connected_with']) ? (string)$_SESSION['connected_with'] : '',
+    'username' => isset($user['username']) ? (string)$user['username'] : '',
+    'status' => isset($user['status']) ? (string)$user['status'] : '',
+  );
+}