diff --git a/Classes/Slot/GetSystemInformationSlot.php b/Classes/Slot/GetSystemInformationSlot.php
new file mode 100644
index 00000000..2b695aa5
--- /dev/null
+++ b/Classes/Slot/GetSystemInformationSlot.php
@@ -0,0 +1,154 @@
+<?php
+namespace T3kit\themeT3kit\Slot;
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Backend\Toolbar\Enumeration\InformationStatus;
+use TYPO3\CMS\Core\Database\ConnectionPool;
+use TYPO3\CMS\Core\TypoScript\ExtendedTemplateService;
+use TYPO3\CMS\Core\Utility\RootlineUtility;
+use TYPO3\CMS\Extbase\Service\TypoScriptService;
+use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;
+use TYPO3\CMS\Backend\Backend\ToolbarItems\SystemInformationToolbarItem;
+
+/**
+ * Render custom system info to toolbar item
+ */
+class GetSystemInformationSlot
+{
+    /**
+     * Signal slot getSystemInformation
+     *
+     * @param SystemInformationToolbarItem $sysInfoToolbarItem sysInfoToolbarItem
+     *
+     * @return void
+     */
+    public function getSystemInformation($sysInfoToolbarItem)
+    {
+        $this->getThemeMode($sysInfoToolbarItem);
+    }
+
+    /**
+     * Get theme mode to system information
+     *
+     * @param SystemInformationToolbarItem $sysInfoToolbarItem sysInfoToolbarItem
+     *
+     * @return void
+     */
+    protected function getThemeMode($sysInfoToolbarItem)
+    {
+        if (ExtensionManagementUtility::isLoaded('themes')) {
+
+            $rootSysTemplates = $this->getRootSysTemplates();
+
+            if (!empty($rootSysTemplates) && is_array($rootSysTemplates)) {
+                foreach ($rootSysTemplates as $index => $rootSysTemplate) {
+
+                    $themeConfiguration = $this->getThemeConfiguration(
+                        $rootSysTemplate
+                    );
+                    if (!empty($themeConfiguration)
+                        && is_array($themeConfiguration)
+                    ) {
+
+                        $inProductionMode
+                            = $themeConfiguration['isDevelopment'] === '0';
+
+                        $themeMode = $inProductionMode
+                            ? 'Production'
+                            : 'Development';
+
+                        $themeStatus = $inProductionMode
+                            ? InformationStatus::STATUS_OK
+                            : InformationStatus::STATUS_WARNING;
+            
+                        $sysInfoToolbarItem->addSystemInformation(
+                            'Theme mode [' . $rootSysTemplate['pid'] . ']',
+                            $themeMode,
+                            'sysinfo-application-context',
+                            $themeStatus
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Get root templates
+     *
+     * @return array
+     */
+    protected function getRootSysTemplates()
+    {
+        $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)
+            ->getQueryBuilderForTable('sys_template');
+        $rootSysTemplates = $queryBuilder
+            ->select('*')
+            ->from('sys_template')
+            ->where(
+                $queryBuilder->expr()->eq(
+                    'root',
+                    $queryBuilder->createNamedParameter(1, \PDO::PARAM_INT)
+                )
+            )
+            ->execute()
+            ->fetchAll();
+        return $rootSysTemplates;
+    }
+
+    /**
+     * Fetch theme configuration constants
+     *
+     * @param array $sysTemplate System Template
+     *
+     * @return array
+     */
+    protected function getThemeConfiguration($sysTemplate)
+    {
+        $themeConfiguration = false;
+        $templateService = GeneralUtility::makeInstance(
+            ExtendedTemplateService::class
+        );
+        $typoScriptService = GeneralUtility::makeInstance(
+            TypoScriptService::class
+        );
+        $templateService->init();
+
+        $templateUid = $sysTemplate['uid'];
+        $pageId = $sysTemplate['pid'];
+
+        $rootlineUtility = GeneralUtility::makeInstance(
+            RootlineUtility::class,
+            $pageId
+        );
+        $rootLine = $rootlineUtility->get();
+
+        $templateService->runThroughTemplates($rootLine, $templateUid);
+        $templateService->generateConfig();
+
+        $themeConfiguration = $templateService
+            ->setup_constants['themes.']['configuration.'];
+
+        if (!empty($themeConfiguration) && is_array($themeConfiguration)) {
+            $themeConfiguration = $typoScriptService
+                ->convertTypoScriptArrayToPlainArray(
+                    $themeConfiguration
+                );
+        }
+
+        return  $themeConfiguration;
+    }
+}
diff --git a/ext_localconf.php b/ext_localconf.php
index e89c923e..effca47a 100644
--- a/ext_localconf.php
+++ b/ext_localconf.php
@@ -60,3 +60,15 @@
     = \T3kit\themeT3kit\Xclass\Realurl\Utility::class;
 
 $GLOBALS['TYPO3_CONF_VARS']['BE']['interfaces'] = 'frontend,backend';
+
+// register to signal slot from SystemInformationToolbarItem to include
+// Themes Development Mode constant setting per "siteroot" to system information
+$signalSlotDispatcher = TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(
+    \TYPO3\CMS\Extbase\SignalSlot\Dispatcher::class
+);
+$signalSlotDispatcher->connect(
+    \TYPO3\CMS\Backend\Backend\ToolbarItems\SystemInformationToolbarItem::class,
+    'getSystemInformation',
+    \T3kit\themeT3kit\Slot\GetSystemInformationSlot::class,
+    'getSystemInformation'
+);