diff --git a/lbplanner/classes/enums/SETTINGS.php b/lbplanner/classes/enums/SETTINGS.php
index 26414a50..2c43a255 100644
--- a/lbplanner/classes/enums/SETTINGS.php
+++ b/lbplanner/classes/enums/SETTINGS.php
@@ -43,6 +43,10 @@ class SETTINGS extends Enum {
      * NOTE: This is a constant! Do not set outside version.php under ANY circumstances!
      */
     const V_FULLNUM = 'release_fullnum';
+    /**
+     * Key for the panic / fulloff button.
+     */
+    const PANIC = 'panic';
     /**
      * Key for the setting for how many days into the future a student should be able to reserve a slot.
      */
diff --git a/lbplanner/lib.php b/lbplanner/lib.php
index 07eaea0e..59b097bd 100644
--- a/lbplanner/lib.php
+++ b/lbplanner/lib.php
@@ -23,6 +23,7 @@
  */
 
 use local_lbplanner\helpers\sentry_helper;
+use local_lbplanner\enums\SETTINGS;
 
 /**
  * Callback for any webservices that get called by external actors.
@@ -34,6 +35,9 @@
 function local_lbplanner_override_webservice_execution(stdClass $externalfunctioninfo, array $params): mixed {
     // Only override calling our own functions.
     if ($externalfunctioninfo->component === 'local_lbplanner') {
+        if (get_config('local_lbplanner', SETTINGS::PANIC) === '1') {
+            throw new \moodle_exception('PANIC'); // TODO: add to translations.
+        }
         sentry_helper::init();
         // Actually calling the function (since we're overriding this part, duh).
         try {
diff --git a/lbplanner/settings.php b/lbplanner/settings.php
index 827607f2..e36e054a 100644
--- a/lbplanner/settings.php
+++ b/lbplanner/settings.php
@@ -66,4 +66,12 @@
         PARAM_TEXT
     );
     $settings->add($sentrydsnsett);
+
+    $panicsett = new admin_setting_configcheckbox(
+        'local_lbplanner/' . SETTINGS::PANIC,
+        'PANIC SWITCH',
+        'Turns API off - only use in emergencies. No data loss, but total loss of EduPlanner services until box is unchecked.',
+        '0',
+    );
+    $settings->add($panicsett);
 }