diff --git a/examples/FileUpload/FileUpload.ino b/examples/FileUpload/FileUpload.ino
index 6bc4c48..eef78ca 100644
--- a/examples/FileUpload/FileUpload.ino
+++ b/examples/FileUpload/FileUpload.ino
@@ -115,10 +115,10 @@ String postUpload(AutoConnectAux& aux, PageArgument& args) {
   String  content;
   // Explicitly cast to the desired element to correctly extract
   // the element using the operator [].
-  AutoConnectFile&  filename = (AutoConnectFile&)auxUpload["filename"];
-  AutoConnectText&  aux_filename = (AutoConnectText&)aux["filename"];
-  AutoConnectText&  aux_size = (AutoConnectText&)aux["size"];
-  AutoConnectText&  aux_contentType = (AutoConnectText&)aux["content_type"];
+  AutoConnectFile&  filename = auxUpload["filename"].as<AutoConnectFile>();
+  AutoConnectText&  aux_filename = aux["filename"].as<AutoConnectText>();
+  AutoConnectText&  aux_size = aux["size"].as<AutoConnectText>();
+  AutoConnectText&  aux_contentType = aux["content_type"].as<AutoConnectText>();
   // Assignment operator can be used for the element attribute.
   aux_filename.value = filename.value;
   aux_size.value = String(filename.size);
diff --git a/examples/Simple/Simple.ino b/examples/Simple/Simple.ino
index 489fad5..ecbe93e 100644
--- a/examples/Simple/Simple.ino
+++ b/examples/Simple/Simple.ino
@@ -158,7 +158,7 @@ void setup() {
   Timezone.load(AUX_TIMEZONE);
   // Retrieve the select element that holds the time zone code and
   // register the zone mnemonic in advance.
-  AutoConnectSelect&  tz = Timezone.getElement<AutoConnectSelect>("timezone");
+  AutoConnectSelect&  tz = Timezone["timezone"].as<AutoConnectSelect>();
   for (uint8_t n = 0; n < sizeof(TZ) / sizeof(Timezone_t); n++) {
     tz.add(String(TZ[n].zone));
   }
diff --git a/examples/mqttRSSI/mqttRSSI.ino b/examples/mqttRSSI/mqttRSSI.ino
index 3052261..15d69b4 100644
--- a/examples/mqttRSSI/mqttRSSI.ino
+++ b/examples/mqttRSSI/mqttRSSI.ino
@@ -256,42 +256,38 @@ String loadParams(AutoConnectAux& aux, PageArgument& args) {
 String saveParams(AutoConnectAux& aux, PageArgument& args) {
   // The 'where()' function returns the AutoConnectAux that caused
   // the transition to this page.
-  AutoConnectAux*   mqtt_setting = portal.where();
+  AutoConnectAux&   mqtt_setting = portal.where();
 
-  AutoConnectInput& mqttserver = mqtt_setting->getElement<AutoConnectInput>("mqttserver");
+  AutoConnectInput& mqttserver = mqtt_setting["mqttserver"].as<AutoConnectInput>();
   serverName = mqttserver.value;
   serverName.trim();
 
-  AutoConnectInput& channelid = mqtt_setting->getElement<AutoConnectInput>("channelid");
-  channelId = channelid.value;
+  channelId = mqtt_setting["channelid"].value;
   channelId.trim();
 
-  AutoConnectInput& userkey = mqtt_setting->getElement<AutoConnectInput>("userkey");
-  userKey = userkey.value;
+  userKey = mqtt_setting["userkey"].value;
   userKey.trim();
 
-  AutoConnectInput& apikey = mqtt_setting->getElement<AutoConnectInput>("apikey");
-  apiKey = apikey.value;
+  apiKey = mqtt_setting["apikey"].value;
   apiKey.trim();
 
-  AutoConnectRadio& period = mqtt_setting->getElement<AutoConnectRadio>("period");
+  AutoConnectRadio& period = mqtt_setting["period"].as<AutoConnectRadio>();
   updateInterval = period.value().substring(0, 2).toInt() * 1000;
 
-  bool uniqueid = mqtt_setting->getElement<AutoConnectCheckbox>("uniqueid").checked;
+  bool uniqueid = mqtt_setting["uniqueid"].as<AutoConnectCheckbox>().checked;
 
-  AutoConnectInput& hostname = mqtt_setting->getElement<AutoConnectInput>("hostname");
-  hostName = hostname.value;
+  hostName = mqtt_setting["hostname"].value;
   hostName.trim();
 
   // The entered value is owned by AutoConnectAux of /mqtt_setting.
   // To retrieve the elements of /mqtt_setting, it is necessary to get
   // the AutoConnectAux object of /mqtt_setting.
   File param = SPIFFS.open(PARAM_FILE, "w");
-  mqtt_setting->saveElement(param, { "mqttserver", "channelid", "userkey", "apikey", "uniqueid", "hostname" });
+  mqtt_setting.saveElement(param, { "mqttserver", "channelid", "userkey", "apikey", "uniqueid", "hostname" });
   param.close();
 
   // Echo back saved parameters to AutoConnectAux page.
-  AutoConnectText&  echo = aux.getElement<AutoConnectText>("parameters");
+  AutoConnectText&  echo = aux["parameters"].as<AutoConnectText>();
   echo.value = "Server: " + serverName;
   echo.value += mqttserver.isValid() ? String(" (OK)") : String(" (ERR)");
   echo.value += "<br>Channel ID: " + channelId + "<br>";
@@ -354,9 +350,9 @@ void setup() {
   SPIFFS.begin();
 
   if (portal.load(FPSTR(AUX_mqtt_setting))) {
-    AutoConnectAux* mqtt_setting = portal.aux(AUX_SETTING_URI);
-    AutoConnectCheckbox&  uniqueidElm = mqtt_setting->getElement<AutoConnectCheckbox>("uniqueid");
-    AutoConnectInput&     hostnameElm = mqtt_setting->getElement<AutoConnectInput>("hostname");
+    AutoConnectAux& mqtt_setting = *portal.aux(AUX_SETTING_URI);
+    AutoConnectCheckbox&  uniqueidElm = mqtt_setting["uniqueid"].as<AutoConnectCheckbox>();
+    AutoConnectInput&     hostnameElm = mqtt_setting["hostname"].as<AutoConnectInput>();
     if (uniqueidElm.checked) {
       config.apid = String("ESP") + "-" + String(GET_CHIPID(), HEX);
       Serial.println("apid set to " + config.apid);
diff --git a/examples/mqttRSSI_FS/mqttRSSI_FS.ino b/examples/mqttRSSI_FS/mqttRSSI_FS.ino
index 9a3ac21..59e8bca 100644
--- a/examples/mqttRSSI_FS/mqttRSSI_FS.ino
+++ b/examples/mqttRSSI_FS/mqttRSSI_FS.ino
@@ -149,7 +149,7 @@ String saveParams(AutoConnectAux& aux, PageArgument& args) {
   param.close();
 
   // Echo back saved parameters to AutoConnectAux page.
-  AutoConnectText&  echo = aux.getElement<AutoConnectText>("parameters");
+  AutoConnectText&  echo = aux["parameters"].as<AutoConnectText>();
   echo.value = "Server: " + serverName + "<br>";
   echo.value += "Channel ID: " + channelId + "<br>";
   echo.value += "User Key: " + userKey + "<br>";
@@ -231,9 +231,10 @@ void setup() {
   AutoConnectAux* setting = portal.aux(AUX_MQTTSETTING);
   if (setting) {
     PageArgument  args;
-    loadParams(*setting, args);
-    AutoConnectCheckbox&  uniqueidElm = setting->getElement<AutoConnectCheckbox>("uniqueid");
-    AutoConnectInput&     hostnameElm = setting->getElement<AutoConnectInput>("hostname");
+    AutoConnectAux& mqtt_setting = *setting;
+    loadParams(mqtt_setting, args);
+    AutoConnectCheckbox&  uniqueidElm = mqtt_setting["uniqueid"].as<AutoConnectCheckbox>();
+    AutoConnectInput&     hostnameElm = mqtt_setting["hostname"].as<AutoConnectInput>();
     if (uniqueidElm.checked) {
       config.apid = String("ESP") + "-" + String(GET_CHIPID(), HEX);
       Serial.println("apid set to " + config.apid);
diff --git a/src/AutoConnect.h b/src/AutoConnect.h
index 2c697e6..8519342 100644
--- a/src/AutoConnect.h
+++ b/src/AutoConnect.h
@@ -185,7 +185,7 @@ class AutoConnect {
   void  join(AutoConnectAux& aux);
   void  join(AutoConnectAuxVT auxVector);
   bool  on(const String& uri, const AuxHandlerFunctionT handler, AutoConnectExitOrder_t order = AC_EXIT_AHEAD);
-  AutoConnectAux* where(void) const { return aux(_auxUri); }
+  AutoConnectAux& where(void) const { return *aux(_auxUri); }
 
   /** For AutoConnectAux described in JSON */
 #ifdef AUTOCONNECT_USE_JSON
@@ -220,6 +220,8 @@ class AutoConnect {
   void  _purgePages(void);
   virtual PageElement*  _setupPage(String uri);
 #ifdef AUTOCONNECT_USE_JSON
+  template<typename T>
+  bool  _parseJson(T in);
   bool  _load(JsonVariant& aux);
 #endif // !AUTOCONNECT_USE_JSON
 
diff --git a/src/AutoConnectAux.cpp b/src/AutoConnectAux.cpp
index c3328cf..b00b997 100644
--- a/src/AutoConnectAux.cpp
+++ b/src/AutoConnectAux.cpp
@@ -9,8 +9,8 @@
 #include <algorithm>
 #include "AutoConnect.h"
 #include "AutoConnectAux.h"
+#include "AutoConnectAuxImpl.h"
 #include "AutoConnectUploadImpl.h"
-#include "AutoConnectElement.h"
 #include "AutoConnectElementBasisImpl.h"
 #ifdef AUTOCONNECT_USE_JSON
 #include "AutoConnectElementJsonImpl.h"
@@ -466,309 +466,7 @@ void AutoConnectAux::_storeElements(WebServerClass* webServer) {
   }
 }
 
-#ifndef AUTOCONNECT_USE_JSON
-
-/**
- * Get AutoConnectElementBasis element.
- * @param  name  an element name.
- * @return A reference of AutoConnectElement class.
- */
-template<>
-AutoConnectElementBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    return *(reinterpret_cast<AutoConnectElementBasis*>(elm));
-  }
-  return reinterpret_cast<AutoConnectElementBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectButtonBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectButton class.
- */
-template<>
-AutoConnectButtonBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Button)
-      return *(reinterpret_cast<AutoConnectButtonBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectButtonBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectCheckboxBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectCheckbox class.
- */
-template<>
-AutoConnectCheckboxBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Checkbox)
-      return *(reinterpret_cast<AutoConnectCheckboxBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectCheckboxBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectFileBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectFile class.
- */
-template<>
-AutoConnectFileBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_File)
-      return *(reinterpret_cast<AutoConnectFileBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectFileBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectInputBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectInput class.
- */
-template<>
-AutoConnectInputBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Input)
-      return *(reinterpret_cast<AutoConnectInputBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectInputBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectRadioBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectRadio class.
- */
-template<>
-AutoConnectRadioBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Radio)
-      return *(reinterpret_cast<AutoConnectRadioBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectRadioBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectSelectBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectSelect class.
- */
-template<>
-AutoConnectSelectBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Select)
-      return *(reinterpret_cast<AutoConnectSelectBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectSelectBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectSubmitBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectSubmit class.
- */
-template<>
-AutoConnectSubmitBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Submit)
-      return *(reinterpret_cast<AutoConnectSubmitBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectSubmitBasis&>(_nullElement());
-}
-
-/**
- * Get AutoConnectTextBasis element.
- * @param  name  An element name.
- * @return A reference of AutoConnectText class.
- */
-template<>
-AutoConnectTextBasis& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Text)
-      return *(reinterpret_cast<AutoConnectTextBasis*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectTextBasis&>(_nullElement());
-}
-
-#else
-
-/**
- * Get AutoConnectElementJson element.
- * @param  name  an element name.
- * @return A reference of AutoConnectElement class.
- */
-template<>
-AutoConnectElementJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    return *(reinterpret_cast<AutoConnectElementJson*>(elm));
-  }
-  return reinterpret_cast<AutoConnectElementJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectButtonJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectButton class.
- */
-template<>
-AutoConnectButtonJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Button)
-      return *(reinterpret_cast<AutoConnectButtonJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectButtonJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectCheckboxJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectCheckbox class.
- */
-template<>
-AutoConnectCheckboxJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Checkbox)
-      return *(reinterpret_cast<AutoConnectCheckboxJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectCheckboxJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectFile element.
- * @param  name  An element name.
- * @return A reference of AutoConnectFile class.
- */
-template<>
-AutoConnectFileJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_File)
-      return *(reinterpret_cast<AutoConnectFileJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectFileJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectInputJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectInput class.
- */
-template<>
-AutoConnectInputJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Input)
-      return *(reinterpret_cast<AutoConnectInputJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectInputJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectRadioJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectRadio class.
- */
-template<>
-AutoConnectRadioJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Radio)
-      return *(reinterpret_cast<AutoConnectRadioJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectRadioJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectSelectJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectSelect class.
- */
-template<>
-AutoConnectSelectJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Select)
-      return *(reinterpret_cast<AutoConnectSelectJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectSelectJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectSubmitJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectSubmit class.
- */
-template<>
-AutoConnectSubmitJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Submit)
-      return *(reinterpret_cast<AutoConnectSubmitJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectSubmitJson&>(_nullElement());
-}
-
-/**
- * Get AutoConnectTextJson element.
- * @param  name  An element name.
- * @return A reference of AutoConnectText class.
- */
-template<>
-AutoConnectTextJson& AutoConnectAux::getElement(const String& name) {
-  AutoConnectElement* elm = getElement(name);
-  if (elm) {
-    if (elm->typeOf() == AC_Text)
-      return *(reinterpret_cast<AutoConnectTextJson*>(elm));
-    else
-      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
-  }
-  return reinterpret_cast<AutoConnectTextJson&>(_nullElement());
-}
+#ifdef AUTOCONNECT_USE_JSON
 
 /**
  * Load AutoConnectAux page from JSON description stored in the sketch.
@@ -778,35 +476,29 @@ AutoConnectTextJson& AutoConnectAux::getElement(const String& name) {
  * @return true Successfully loaded.
  */
 bool AutoConnect::load(const String& aux) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonVariant jv = jsonBuffer.parse(aux);
-  return _load(jv);
+  return _parseJson<const String&>(aux);
 }
 
 /**
-* Load AutoConnectAux page from JSON description stored in PROGMEM.
-* This function can load AutoConnectAux for multiple AUX pages written
-* in JSON and is registered in AutoConnect.
-* @param  aux  JSON description to be load.
-* @return true Successfully loaded.
-*/
+ * Load AutoConnectAux page from JSON description stored in PROGMEM.
+ * This function can load AutoConnectAux for multiple AUX pages written
+ * in JSON and is registered in AutoConnect.
+ * @param  aux  JSON description to be load.
+ * @return true Successfully loaded.
+ */
 bool AutoConnect::load(const __FlashStringHelper* aux) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonVariant jv = jsonBuffer.parse(aux);
-  return _load(jv);
+  return _parseJson<const __FlashStringHelper*>(aux);
 }
 
 /**
-* Load AutoConnectAux page from JSON description from the stream.
-* This function can load AutoConnectAux for multiple AUX pages written
-* in JSON and is registered in AutoConnect.
-* @param  aux  Stream for read AutoConnectAux elements.
-* @return true Successfully loaded.
-*/
+ * Load AutoConnectAux page from JSON description from the stream.
+ * This function can load AutoConnectAux for multiple AUX pages written
+ * in JSON and is registered in AutoConnect.
+ * @param  aux  Stream for read AutoConnectAux elements.
+ * @return true Successfully loaded.
+ */
 bool AutoConnect::load(Stream& aux) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonVariant jv = jsonBuffer.parse(aux);
-  return _load(jv);
+  return _parseJson<Stream&>(aux);
 }
 
 /**
@@ -815,34 +507,29 @@ bool AutoConnect::load(Stream& aux) {
  * @return true Successfully loaded.
  */
 bool AutoConnect::_load(JsonVariant& auxJson) {
-  bool  rc = auxJson.success();
-  if (rc) {
-    if (auxJson.is<JsonArray>()) {
-      JsonArray& jb = auxJson.as<JsonArray>();
-      for (JsonObject& auxJson : jb) {
-        AutoConnectAux* newAux = new AutoConnectAux;
-        if (newAux->_load(auxJson))
-          join(*newAux);
-        else {
-          delete newAux;
-          rc = false;
-          break;
-        }
-      }
-    }
-    else {
-      JsonObject& jb = auxJson.as<JsonObject>();
+  bool  rc = true;
+  if (auxJson.is<JsonArray>()) {
+    ArduinoJsonArray  jb = auxJson.as<JsonArray>();
+    for (ArduinoJsonObject  auxJson : jb) {
       AutoConnectAux* newAux = new AutoConnectAux;
-      if (newAux->_load(jb))
+      if (newAux->_load(auxJson))
         join(*newAux);
       else {
         delete newAux;
         rc = false;
+        break;
       }
     }
   }
   else {
-    AC_DBG("JSON parse error\n");
+    ArduinoJsonObject jb = auxJson.as<JsonObject>();
+    AutoConnectAux* newAux = new AutoConnectAux;
+    if (newAux->_load(jb))
+      join(*newAux);
+    else {
+      delete newAux;
+      rc = false;
+    }
   }
   return rc;
 }
@@ -854,7 +541,7 @@ bool AutoConnect::_load(JsonVariant& auxJson) {
  */
 AutoConnectElement* AutoConnectAux::_createElement(const JsonObject& json) {
   AutoConnectElement* elm = nullptr;
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
 
   switch (_asElementType(type)) {
   case AC_Element:
@@ -906,9 +593,7 @@ AutoConnectElement* AutoConnectAux::_createElement(const JsonObject& json) {
  * @return false Invalid JSON data occurred. 
  */
 bool AutoConnectAux::load(const String& in) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonObject& jb = jsonBuffer.parseObject(in);
-  return _load(jb);
+  return _parseJson<const String&>(in);
 }
 
 /**
@@ -920,9 +605,7 @@ bool AutoConnectAux::load(const String& in) {
  * @return false Invalid JSON data occurred. 
  */
 bool AutoConnectAux::load(const __FlashStringHelper* in) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonObject& jb = jsonBuffer.parseObject(in);
-  return _load(jb);
+  return _parseJson<const __FlashStringHelper*>(in);
 }
 
 /**
@@ -934,9 +617,7 @@ bool AutoConnectAux::load(const __FlashStringHelper* in) {
  * @return false Invalid JSON data occurred. 
  */
 bool AutoConnectAux::load(Stream& in) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonObject& jb = jsonBuffer.parseObject(in);
-  return _load(jb);
+  return _parseJson<Stream&>(in);
 }
 
 /**
@@ -946,15 +627,10 @@ bool AutoConnectAux::load(Stream& in) {
  * @return false loading unsuccessful, JSON parsing error occurred.
  */
 bool AutoConnectAux::_load(JsonObject& jb) {
-  if (!jb.success()) {
-    AC_DBG("json parse error\n");
-    return false;
-  }
-
-  _title = jb.get<String>(F(AUTOCONNECT_JSON_KEY_TITLE));
-  _uriStr = jb.get<String>(F(AUTOCONNECT_JSON_KEY_URI));
+  _title = jb[F(AUTOCONNECT_JSON_KEY_TITLE)].as<String>();
+  _uriStr = jb[F(AUTOCONNECT_JSON_KEY_URI)].as<String>();
   _uri = _uriStr.c_str();
-  _menu = jb.get<bool>(F(AUTOCONNECT_JSON_KEY_MENU));
+  _menu = jb[F(AUTOCONNECT_JSON_KEY_MENU)].as<bool>();
   JsonVariant elements = jb[F(AUTOCONNECT_JSON_KEY_ELEMENT)];
   (void)_loadElement(elements, "");
   return true;
@@ -971,49 +647,41 @@ bool AutoConnectAux::_load(JsonObject& jb) {
  * @return A reference of loaded AutoConnectElement instance.
  */
 bool AutoConnectAux::loadElement(const String& in, const String& name) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonVariant jb = jsonBuffer.parse(in);
-  return _loadElement(jb, name);
+  return _parseElement<const String&>(in, name);
 }
 
 bool AutoConnectAux::loadElement(const __FlashStringHelper* in, const String& name) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonVariant jb = jsonBuffer.parse(in);
-  return _loadElement(jb, name);
+  return _parseElement<const __FlashStringHelper*>(in, name);
 }
 
 bool AutoConnectAux::loadElement(Stream& in, const String& name) {
-  DynamicJsonBuffer jsonBuffer(AUTOCONNECT_JSON_BUFFER_SIZE);
-  JsonVariant jb = jsonBuffer.parse(in);
-  return _loadElement(jb, name);
+  return _parseElement<Stream&>(in, name);
 }
 
 bool AutoConnectAux::_loadElement(JsonVariant& jb, const String& name) {
-  bool  rc = jb.success();
-  if (rc) {
-    if (jb.is<JsonArray>()) {
-      JsonArray&  elements = jb.as<JsonArray>();
-      for (JsonObject& element : elements) {
-        AutoConnectElement& elm = _loadElement(element, name);
-        if (!elm.name.length()) {
-          rc = false;
-          break;
-        }
-      }
-    }
-    else {
-      JsonObject& element = jb.as<JsonObject>();
+  bool  rc = true;
+  if (jb.is<JsonArray>()) {
+    ArduinoJsonArray  elements = jb.as<JsonArray>();
+    for (ArduinoJsonObject  element : elements) {
       AutoConnectElement& elm = _loadElement(element, name);
-      if (!elm.name.length())
+      if (!elm.name.length()) {
         rc = false;
+        break;
+      }
     }
   }
+  else {
+    ArduinoJsonObject element = jb.as<JsonObject>();
+    AutoConnectElement& elm = _loadElement(element, name);
+    if (!elm.name.length())
+      rc = false;
+  }
   return rc;
 }
 
 AutoConnectElement& AutoConnectAux::_loadElement(JsonObject& element, const String& name) {
   AutoConnectElement* auxElm = nullptr;
-  String  elmName = element.get<String>(F(AUTOCONNECT_JSON_KEY_NAME));
+  String  elmName = element[F(AUTOCONNECT_JSON_KEY_NAME)].as<String>();
   if (!name.length() || name.equalsIgnoreCase(elmName)) {
     // The specified element is defined in the JSON stream.
     // Loads from JSON object.
@@ -1067,40 +735,43 @@ size_t AutoConnectAux::saveElement(Stream& out, std::vector<String> const& names
         bufferSize += elm.getObjectSize();
         break;
       }
+  // Round up to 16 boundary
+  bufferSize = bufferSize > 0 ? ((bufferSize + 16) & (~0xf)) : bufferSize;
 
+  // Serialization
   if (bufferSize > 0) {
-    DynamicJsonBuffer jb(bufferSize);
+    ArduinoJsonBuffer jb(bufferSize);
     if (amount == 1) {
-      JsonObject& element = jb.createObject();
+      ArduinoJsonObject element = ARDUINOJSON_CREATEOBJECT(jb);
       for (AutoConnectElement& elm : _addonElm)
         if (elm.name.equalsIgnoreCase(names[0])) {
           elm.serialize(element);
           break;
         }
-      size_n = element.printTo(out);
+      size_n = ARDUINOJSON_PRINT(element, out);
     }
     else if (amount == 0) {
-      JsonObject& json = jb.createObject();
+      ArduinoJsonObject json = ARDUINOJSON_CREATEOBJECT(jb);
       json[F(AUTOCONNECT_JSON_KEY_TITLE)] = _title;
       json[F(AUTOCONNECT_JSON_KEY_URI)] = _uriStr;
       json[F(AUTOCONNECT_JSON_KEY_MENU)] = _menu;
-      JsonArray&  elements = json.createNestedArray(F(AUTOCONNECT_JSON_KEY_ELEMENT));
+      ArduinoJsonArray  elements = json.createNestedArray(F(AUTOCONNECT_JSON_KEY_ELEMENT));
       for (AutoConnectElement& elm : _addonElm) {
-        JsonObject& element = elements.createNestedObject();
+        ArduinoJsonObject element = elements.createNestedObject();
         elm.serialize(element);
       }
-      size_n = json.prettyPrintTo(out);
+      size_n = ARDUINOJSON_PRETTYPRINT(json, out);
     }
     else if (amount >= 2) {
-      JsonArray& elements = jb.createArray();
+      ArduinoJsonArray  elements = ARDUINOJSON_CREATEARRAY(jb);
       for (String name : names)
         for (AutoConnectElement& elm : _addonElm)
           if (elm.name.equalsIgnoreCase(name)) {
-            JsonObject& element = elements.createNestedObject();
+            ArduinoJsonObject element = elements.createNestedObject();
             elm.serialize(element);
             break;
           }
-      size_n = elements.prettyPrintTo(out);
+      size_n = ARDUINOJSON_PRETTYPRINT(elements, out);
     }
   }
   return size_n;
@@ -1136,4 +807,4 @@ ACElement_t AutoConnectAux::_asElementType(const String& type) {
   return t;
 }
 
-#endif // AUTOCONNECT_USE_JSON
+#endif // !AUTOCONNECT_USE_JSON
diff --git a/src/AutoConnectAux.h b/src/AutoConnectAux.h
index 352e30d..5d7ac7d 100644
--- a/src/AutoConnectAux.h
+++ b/src/AutoConnectAux.h
@@ -88,8 +88,12 @@ class AutoConnectAux : public PageBuilder {
   static AutoConnectElement&  _nullElement(void);                       /**< A static returning value as invalid */
 
 #ifdef AUTOCONNECT_USE_JSON
+  template<typename T>
+  bool  _parseJson(T in);
   bool  _load(JsonObject& in);                                          /**< Load all elements from JSON object */
   bool  _loadElement(JsonVariant& in, const String& name);              /**< Load an element as specified name from JSON object */
+  template<typename T>
+  bool  _parseElement(T in, const String& name);
   AutoConnectElement& _loadElement(JsonObject& in, const String& name); /**< Load an element as specified name from JSON object */
   AutoConnectElement* _createElement(const JsonObject& json);           /**< Create an AutoConnectElement instance from JSON object */
   static ACElement_t  _asElementType(const String& type);         /**< Convert a string of element type to the enumeration value */
diff --git a/src/AutoConnectAuxImpl.h b/src/AutoConnectAuxImpl.h
new file mode 100644
index 0000000..799afbe
--- /dev/null
+++ b/src/AutoConnectAuxImpl.h
@@ -0,0 +1,416 @@
+/**
+ * Implementation of template functions of AutoConnect and AutoConnectAux. 
+ * This implementation instantiates completely the void AutoConnectElement
+ * as each type and also absorbs interface differences due to ArduinoJson
+ * version differences. 
+ * @file AutoConnectAuxImpl.h
+ * @author hieromon@gmail.com
+ * @version  0.9.8
+ * @date 2019-03-21
+ * @copyright  MIT license.
+ */
+
+#ifndef _AUTOCONNECTAUXIMPL_H_
+#define _AUTOCONNECTAUXIMPL_H_
+
+#include "AutoConnectDefs.h"
+
+#ifndef AUTOCONNECT_USE_JSON
+
+/**
+ * Get AutoConnectElementBasis element.
+ * @param  name  an element name.
+ * @return A reference of AutoConnectElement class.
+ */
+template<>
+AutoConnectElementBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    return *(reinterpret_cast<AutoConnectElementBasis*>(elm));
+  }
+  return reinterpret_cast<AutoConnectElementBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectButtonBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectButton class.
+ */
+template<>
+AutoConnectButtonBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Button)
+      return *(reinterpret_cast<AutoConnectButtonBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectButtonBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectCheckboxBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectCheckbox class.
+ */
+template<>
+AutoConnectCheckboxBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Checkbox)
+      return *(reinterpret_cast<AutoConnectCheckboxBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectCheckboxBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectFileBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectFile class.
+ */
+template<>
+AutoConnectFileBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_File)
+      return *(reinterpret_cast<AutoConnectFileBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectFileBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectInputBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectInput class.
+ */
+template<>
+AutoConnectInputBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Input)
+      return *(reinterpret_cast<AutoConnectInputBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectInputBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectRadioBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectRadio class.
+ */
+template<>
+AutoConnectRadioBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Radio)
+      return *(reinterpret_cast<AutoConnectRadioBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectRadioBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectSelectBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectSelect class.
+ */
+template<>
+AutoConnectSelectBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Select)
+      return *(reinterpret_cast<AutoConnectSelectBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectSelectBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectSubmitBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectSubmit class.
+ */
+template<>
+AutoConnectSubmitBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Submit)
+      return *(reinterpret_cast<AutoConnectSubmitBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectSubmitBasis&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectTextBasis element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectText class.
+ */
+template<>
+AutoConnectTextBasis& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Text)
+      return *(reinterpret_cast<AutoConnectTextBasis*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectTextBasis&>(_nullElement());
+}
+
+#else
+
+/**
+ * Parse and load a JSON document which marks up multiple custom web
+ * pages. The compiler instantiates this template according to the stored
+ * data type that contains the JSON document.
+ * This template also generates different parsing function calls
+ * depending on the ArduinoJson version.
+ * @param  T  An object type of the JSON document which must be a
+ * passable object to ArduinoJson.
+ * @param  in An instance of a source JSON document to load.
+ */
+template<typename T>
+bool AutoConnect::_parseJson(T in) {
+  ArduinoJsonBuffer jsonBuffer(AUTOCONNECT_JSONBUFFER_PRIMITIVE_SIZE);
+  JsonVariant jv;
+#if ARDUINOJSON_VERSION_MAJOR<=5
+  jv = jsonBuffer.parse(in);
+  if (!jv.success()) {
+    AC_DBG("JSON parse error\n");
+    return false;
+  }
+#else
+  DeserializationError  err = deserializeJson(jsonBuffer, in);
+  if (err) {
+    AC_DBG("Deserialize error:%s\n", err.c_str());
+    return false;
+  }
+  jv = jsonBuffer.as<JsonVariant>();
+#endif
+  return _load(jv);
+}
+
+/**
+ * Parse and load a JSON document which marks up a custom web page.
+ * The compiler instantiates this template according to the stored data
+ * type that contains the JSON document.
+ * This template also generates different parsing function calls
+ * depending on the ArduinoJson version.
+ * @param  T  An object type of the JSON document which must be a
+ * passable object to ArduinoJson.
+ * @param  in An instance of a source JSON document to load.
+ */
+template<typename T>
+bool AutoConnectAux::_parseJson(T in) {
+  ArduinoJsonBuffer jsonBuffer(AUTOCONNECT_JSONBUFFER_PRIMITIVE_SIZE);
+#if ARDUINOJSON_VERSION_MAJOR<=5
+  JsonObject& jb = jsonBuffer.parseObject(in);
+  if (!jb.success()) {
+    AC_DBG("JSON parse error\n");
+    return false;
+  }
+#else
+  DeserializationError  err = deserializeJson(jsonBuffer, in);
+  if (err) {
+    AC_DBG("Deserialize:%s\n", err.c_str());
+    return false;
+  }
+  JsonObject jb = jsonBuffer.as<JsonObject>();
+#endif
+  return _load(jb);
+}
+
+/**
+ * Parse and load a JSON document which declares one of the AutoConnectElement.
+ * The compiler instantiates this template according to the stored data
+ * type that contains the JSON document.
+ * This template also generates different parsing function calls
+ * depending on the ArduinoJson version.
+ * @param  T  An object type of the JSON document which must be a
+ * passable object to ArduinoJson.
+ * @param  in An instance of a source JSON document to load.
+ */
+template<typename T>
+bool AutoConnectAux::_parseElement(T in, const String& name) {
+  ArduinoJsonBuffer jsonBuffer(AUTOCONNECT_JSONBUFFER_PRIMITIVE_SIZE);
+  JsonVariant jb;
+#if ARDUINOJSON_VERSION_MAJOR<=5
+  jb = jsonBuffer.parse(in);
+  if (!jb.success()) {
+    AC_DBG("JSON parse error\n");
+    return false;
+  }
+#else
+  DeserializationError  err = deserializeJson(jsonBuffer, in);
+  if (err) {
+    AC_DBG("Deserialize:%s\n", err.c_str());
+    return false;
+  }
+  jb = jsonBuffer.as<JsonObject>();
+#endif
+  return _loadElement(jb, name);
+}
+
+/**
+ * Get AutoConnectElementJson element.
+ * @param  name  an element name.
+ * @return A reference of AutoConnectElement class.
+ */
+template<>
+AutoConnectElementJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    return *(reinterpret_cast<AutoConnectElementJson*>(elm));
+  }
+  return reinterpret_cast<AutoConnectElementJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectButtonJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectButton class.
+ */
+template<>
+AutoConnectButtonJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Button)
+      return *(reinterpret_cast<AutoConnectButtonJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectButtonJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectCheckboxJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectCheckbox class.
+ */
+template<>
+AutoConnectCheckboxJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Checkbox)
+      return *(reinterpret_cast<AutoConnectCheckboxJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectCheckboxJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectFile element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectFile class.
+ */
+template<>
+AutoConnectFileJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_File)
+      return *(reinterpret_cast<AutoConnectFileJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectFileJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectInputJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectInput class.
+ */
+template<>
+AutoConnectInputJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Input)
+      return *(reinterpret_cast<AutoConnectInputJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectInputJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectRadioJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectRadio class.
+ */
+template<>
+AutoConnectRadioJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Radio)
+      return *(reinterpret_cast<AutoConnectRadioJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectRadioJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectSelectJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectSelect class.
+ */
+template<>
+AutoConnectSelectJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Select)
+      return *(reinterpret_cast<AutoConnectSelectJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectSelectJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectSubmitJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectSubmit class.
+ */
+template<>
+AutoConnectSubmitJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Submit)
+      return *(reinterpret_cast<AutoConnectSubmitJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectSubmitJson&>(_nullElement());
+}
+
+/**
+ * Get AutoConnectTextJson element.
+ * @param  name  An element name.
+ * @return A reference of AutoConnectText class.
+ */
+template<>
+AutoConnectTextJson& AutoConnectAux::getElement(const String& name) {
+  AutoConnectElement* elm = getElement(name);
+  if (elm) {
+    if (elm->typeOf() == AC_Text)
+      return *(reinterpret_cast<AutoConnectTextJson*>(elm));
+    else
+      AC_DBG("Element<%s> type mismatch<%d>\n", name.c_str(), elm->typeOf());
+  }
+  return reinterpret_cast<AutoConnectTextJson&>(_nullElement());
+}
+
+#endif // !AUTOCONNECT_USE_JSON
+
+#endif // !_AUTOCONNECTAUXIMPL_H_
diff --git a/src/AutoConnectDefs.h b/src/AutoConnectDefs.h
index 90b30a1..dc35053 100644
--- a/src/AutoConnectDefs.h
+++ b/src/AutoConnectDefs.h
@@ -149,6 +149,18 @@
 #define AUTOCONNECT_SD_SPEED    4000000
 #endif
 #endif // !AUTOCONNECT_SD_SPEED
+
+// ArduinoJson buffer size
+#ifndef AUTOCONNECT_JSONBUFFER_SIZE
+#define AUTOCONNECT_JSONBUFFER_SIZE     256
+#endif // !AUTOCONNECT_JSONBUFFER_SIZE
+#ifndef AUTOCONNECT_JSONDOCUMENT_SIZE
+#define AUTOCONNECT_JSONDOCUMENT_SIZE   (8 * 1024)
+#endif // !AUTOCONNECT_JSONDOCUMENT_SIZE
+#ifndef AUTOCONNECT_JSONPSRAM_SIZE
+#define AUTOCONNECT_JSONPSRAM_SIZE      (16* 1024)
+#endif // !AUTOCONNECT_JSONPSRAM_SIZE
+
 // Explicitly avoiding unused warning with token handler of PageBuilder
 #define AC_UNUSED(expr) do { (void)(expr); } while (0)
 
diff --git a/src/AutoConnectElementBasis.h b/src/AutoConnectElementBasis.h
index a718b7e..58643f1 100644
--- a/src/AutoConnectElementBasis.h
+++ b/src/AutoConnectElementBasis.h
@@ -52,6 +52,10 @@ class AutoConnectElementBasis {
   virtual ~AutoConnectElementBasis() {}
   virtual const String  toHTML(void) const { return value; }
   ACElement_t typeOf(void) const { return _type; }
+#ifndef AUTOCONNECT_USE_JSON
+  template<typename T>
+  T&  as(void);
+#endif
 
   String  name;       /**< Element name */
   String  value;      /**< Element value */
@@ -249,4 +253,66 @@ class AutoConnectTextBasis : virtual public AutoConnectElementBasis {
   String  format;     /**< C string that contains the text to be written */
 };
 
+#ifndef AUTOCONNECT_USE_JSON
+/**
+ * Casts only a class derived from the AutoConnectElement class to the
+ * actual element class.
+ */
+template<>
+inline AutoConnectButtonBasis& AutoConnectElementBasis::as<AutoConnectButtonBasis>(void) {
+  if (typeOf() != AC_Button)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectButtonBasis*>(this));
+}
+
+template<>
+inline AutoConnectCheckboxBasis& AutoConnectElementBasis::as<AutoConnectCheckboxBasis>(void) {
+  if (typeOf() != AC_Checkbox)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectCheckboxBasis*>(this));
+}
+
+template<>
+inline AutoConnectFileBasis& AutoConnectElementBasis::as<AutoConnectFileBasis>(void) {
+  if (typeOf() != AC_File)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectFileBasis*>(this));
+}
+
+template<>
+inline AutoConnectInputBasis& AutoConnectElementBasis::as<AutoConnectInputBasis>(void) {
+  if (typeOf() != AC_Input)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectInputBasis*>(this));
+}
+
+template<>
+inline AutoConnectRadioBasis& AutoConnectElementBasis::as<AutoConnectRadioBasis>(void) {
+  if (typeOf() != AC_Radio)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectRadioBasis*>(this));
+}
+
+template<>
+inline AutoConnectSelectBasis& AutoConnectElementBasis::as<AutoConnectSelectBasis>(void) {
+  if (typeOf() != AC_Select)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectSelectBasis*>(this));
+}
+
+template<>
+inline AutoConnectSubmitBasis& AutoConnectElementBasis::as<AutoConnectSubmitBasis>(void) {
+  if (typeOf() != AC_Submit)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectSubmitBasis*>(this));
+}
+
+template<>
+inline AutoConnectTextBasis& AutoConnectElementBasis::as<AutoConnectTextBasis>(void) {
+  if (typeOf() != AC_Text)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectTextBasis*>(this));
+}
+#endif
+
 #endif // _AUTOCONNECTELEMENTBASIS_H_
diff --git a/src/AutoConnectElementBasisImpl.h b/src/AutoConnectElementBasisImpl.h
index 8437da0..43c4cf3 100644
--- a/src/AutoConnectElementBasisImpl.h
+++ b/src/AutoConnectElementBasisImpl.h
@@ -19,6 +19,66 @@
 #endif
 #include "AutoConnectElementBasis.h"
 
+/**
+ * Casts only a class derived from the AutoConnectElement class to the
+ * actual element class.
+ */
+// template<>
+// inline AutoConnectButtonBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Button)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectButtonBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectCheckboxBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Checkbox)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectCheckboxBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectFileBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_File)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectFileBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectInputBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Input)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectInputBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectRadioBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Radio)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectRadioBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectSelectBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Select)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectSelectBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectSubmitBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Submit)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectSubmitBasis&>(*this);
+// }
+
+// template<>
+// inline AutoConnectTextBasis& AutoConnectElementBasis::as(void) {
+//   if (typeOf() != AC_Text)
+//     AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+//   return reinterpret_cast<AutoConnectTextBasis&>(*this);
+// }
+
 /**
  * Generate an HTML <button> element. The onclick behavior depends on
  * the code held in factionf member.
diff --git a/src/AutoConnectElementJson.h b/src/AutoConnectElementJson.h
index bffb427..20b5797 100644
--- a/src/AutoConnectElementJson.h
+++ b/src/AutoConnectElementJson.h
@@ -2,8 +2,8 @@
  * Declaration of AutoConnectElement extended classes using JSON.
  * @file AutoConnectElementJson.h
  * @author hieromon@gmail.com
- * @version  0.9.7
- * @date 2018-11-17
+ * @version  0.9.8
+ * @date 2019-03-11
  * @copyright  MIT license.
  */
 
@@ -45,6 +45,50 @@
 #define AUTOCONNECT_JSON_VALUE_SD         "sd"
 #define AUTOCONNECT_JSON_VALUE_VERTICAL   "vertical"
 
+/**
+ * Make the Json types and functions consistent with the ArduinoJson
+ * version. These declarations share the following type definitions:
+ * - Difference between reference and proxy of JsonObject and JsonArray.
+ * - Difference of check whether the parsing succeeded or not.
+ * - The print function name difference.
+ * - The buffer class difference.
+ * - When PSRAM present, enables the buffer allocation it with ESP32 and
+ *   supported version.
+ */
+#if ARDUINOJSON_VERSION_MAJOR<=5
+#define ARDUINOJSON_CREATEOBJECT(doc)     doc.createObject()
+#define ARDUINOJSON_CREATEARRAY(doc)      doc.createArray()
+#define ARDUINOJSON_PRETTYPRINT(doc, out) ({ size_t s = doc.prettyPrintTo(out); s; })
+#define ARDUINOJSON_PRINT(doc, out)       ({ size_t s = doc.printTo(out); s; })
+using ArduinoJsonObject = JsonObject&;
+using ArduinoJsonArray = JsonArray&;
+using ArduinoJsonBuffer = DynamicJsonBuffer;
+#define AUTOCONNECT_JSONBUFFER_PRIMITIVE_SIZE AUTOCONNECT_JSONBUFFER_SIZE
+#else
+#define ARDUINOJSON_CREATEOBJECT(doc)     doc.to<JsonObject>()
+#define ARDUINOJSON_CREATEARRAY(doc)      doc.to<JsonArray>()
+#define ARDUINOJSON_PRETTYPRINT(doc, out) ({ size_t s = serializeJsonPretty(doc, out); s; })
+#define ARDUINOJSON_PRINT(doc, out)       ({ size_t s = serializeJson(doc, out); s; })
+using ArduinoJsonObject = JsonObject;
+using ArduinoJsonArray = JsonArray;
+#if defined(BOARD_HAS_PSRAM) && ((ARDUINOJSON_VERSION_MAJOR==6 && ARDUINOJSON_VERSION_MINOR>=10) || ARDUINOJSON_VERSION_MAJOR>6)
+// JsonDocument is assigned to PSRAM by ArduinoJson's custom allocator.
+struct SpiRamAllocatorST {
+  void* allocate(size_t size) {
+    return heap_caps_malloc(size, MALLOC_CAP_SPIRAM);
+  }
+  void  deallocate(void* pointer) {
+    heap_caps_free(pointer);
+  }
+};
+#define AUTOCONNECT_JSONBUFFER_PRIMITIVE_SIZE AUTOCONNECT_JSONPSRAM_SIZE
+using ArduinoJsonBuffer = BasicJsonDocument<SpiRamAllocatorST>;
+#else
+#define AUTOCONNECT_JSONBUFFER_PRIMITIVE_SIZE AUTOCONNECT_JSONDOCUMENT_SIZE
+using ArduinoJsonBuffer = DynamicJsonDocument;
+#endif
+#endif
+
 /**
  * AutoConnectAux element base with handling with JSON object.
  * Placed a raw text that can be added by user sketch.
@@ -61,6 +105,8 @@ class AutoConnectElementJson : virtual public AutoConnectElementBasis {
   virtual size_t  getObjectSize(void) const;
   virtual bool  loadMember(const JsonObject& json);
   virtual void  serialize(JsonObject& json);
+  template<typename T>
+  T&  as(void);
 
  protected:
   void  _setMember(const JsonObject& json);
@@ -247,4 +293,64 @@ class AutoConnectTextJson : public AutoConnectElementJson, public AutoConnectTex
   void  serialize(JsonObject& json) override;
 };
 
+/**
+ * Casts only a class derived from the AutoConnectElement class to the
+ * actual element class.
+ */
+template<>
+inline AutoConnectButtonJson& AutoConnectElementJson::as<AutoConnectButtonJson>(void) {
+  if (typeOf() != AC_Button)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectButtonJson*>(this));
+}
+
+template<>
+inline AutoConnectCheckboxJson& AutoConnectElementJson::as<AutoConnectCheckboxJson>(void) {
+  if (typeOf() != AC_Checkbox)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectCheckboxJson*>(this));
+}
+
+template<>
+inline AutoConnectFileJson& AutoConnectElementJson::as<AutoConnectFileJson>(void) {
+  if (typeOf() != AC_File)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectFileJson*>(this));
+}
+
+template<>
+inline AutoConnectInputJson& AutoConnectElementJson::as<AutoConnectInputJson>(void) {
+  if (typeOf() != AC_Input)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectInputJson*>(this));
+}
+
+template<>
+inline AutoConnectRadioJson& AutoConnectElementJson::as<AutoConnectRadioJson>(void) {
+  if (typeOf() != AC_Radio)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectRadioJson*>(this));
+}
+
+template<>
+inline AutoConnectSelectJson& AutoConnectElementJson::as<AutoConnectSelectJson>(void) {
+  if (typeOf() != AC_Select)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectSelectJson*>(this));
+}
+
+template<>
+inline AutoConnectSubmitJson& AutoConnectElementJson::as<AutoConnectSubmitJson>(void) {
+  if (typeOf() != AC_Submit)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectSubmitJson*>(this));
+}
+
+template<>
+inline AutoConnectTextJson& AutoConnectElementJson::as<AutoConnectTextJson>(void) {
+  if (typeOf() != AC_Text)
+    AC_DBG("%s mismatched type as <%d>\n", name.c_str(), (int)typeOf());
+  return *(reinterpret_cast<AutoConnectTextJson*>(this));
+}
+
 #endif // _AUTOCONNECTELEMENTJSON_H_
diff --git a/src/AutoConnectElementJsonImpl.h b/src/AutoConnectElementJsonImpl.h
index eb53214..285a29f 100644
--- a/src/AutoConnectElementJsonImpl.h
+++ b/src/AutoConnectElementJsonImpl.h
@@ -27,7 +27,7 @@ size_t AutoConnectElementJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectElementJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACELEMENT))) {
     _setMember(json);
     return true;
@@ -41,8 +41,8 @@ bool AutoConnectElementJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectElementJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACELEMENT));
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACELEMENT));
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
 }
 
 /**
@@ -51,7 +51,7 @@ void AutoConnectElementJson::serialize(JsonObject& json) {
  * @param  json  JSON object to be serialized.
  */
 void AutoConnectElementJson::_serialize(JsonObject& json) {
-  json.set(F(AUTOCONNECT_JSON_KEY_NAME), name);
+  json[F(AUTOCONNECT_JSON_KEY_NAME)] = name;
 }
 
 /**
@@ -59,9 +59,9 @@ void AutoConnectElementJson::_serialize(JsonObject& json) {
  * @param  json  JSON object with the definition of AutoConnectElement.
  */
 void AutoConnectElementJson::_setMember(const JsonObject& json) {
-  name = json.get<String>(F(AUTOCONNECT_JSON_KEY_NAME));
+  name = json[F(AUTOCONNECT_JSON_KEY_NAME)].as<String>();
   if (json.containsKey(F(AUTOCONNECT_JSON_KEY_VALUE)))
-    value = json.get<String>(F(AUTOCONNECT_JSON_KEY_VALUE));
+    value = json[F(AUTOCONNECT_JSON_KEY_VALUE)].as<String>();
 }
 
 /**
@@ -79,11 +79,11 @@ size_t AutoConnectButtonJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectButtonJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACBUTTON))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_ACTION)))
-      action = json.get<String>(F(AUTOCONNECT_JSON_KEY_ACTION));
+      action = json[F(AUTOCONNECT_JSON_KEY_ACTION)].as<String>();
     return true;
   }
   return false;
@@ -95,9 +95,9 @@ bool AutoConnectButtonJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectButtonJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACBUTTON));
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
-  json.set(F(AUTOCONNECT_JSON_KEY_ACTION), action);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACBUTTON));
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
+  json[F(AUTOCONNECT_JSON_KEY_ACTION)] = action;
 }
 
 /**
@@ -115,13 +115,13 @@ size_t AutoConnectCheckboxJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectCheckboxJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACCHECKBOX))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_LABEL)))
-      label = json.get<String>(F(AUTOCONNECT_JSON_KEY_LABEL));
+      label = json[F(AUTOCONNECT_JSON_KEY_LABEL)].as<String>();
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_CHECKED)))
-      checked = json.get<bool>(F(AUTOCONNECT_JSON_KEY_CHECKED));
+      checked = json[F(AUTOCONNECT_JSON_KEY_CHECKED)].as<bool>();
     return true;
   }
   return false;
@@ -133,11 +133,11 @@ bool AutoConnectCheckboxJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectCheckboxJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACCHECKBOX));
-  json.set(F(AUTOCONNECT_JSON_KEY_NAME), name);
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
-  json.set(F(AUTOCONNECT_JSON_KEY_LABEL), label);
-  json.set(F(AUTOCONNECT_JSON_KEY_CHECKED), checked);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACCHECKBOX));
+  json[F(AUTOCONNECT_JSON_KEY_NAME)] = name;
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
+  json[F(AUTOCONNECT_JSON_KEY_LABEL)] = label;
+  json[F(AUTOCONNECT_JSON_KEY_CHECKED)] = checked;
 }
 
 /**
@@ -155,13 +155,13 @@ size_t AutoConnectFileJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectFileJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACFILE))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_LABEL)))
-      label = json.get<String>(F(AUTOCONNECT_JSON_KEY_LABEL));
+      label = json[F(AUTOCONNECT_JSON_KEY_LABEL)].as<String>();
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_STORE))) {
-      String  media = json.get<String>(F(AUTOCONNECT_JSON_KEY_STORE));
+      String  media = json[F(AUTOCONNECT_JSON_KEY_STORE)].as<String>();
       if (media.equalsIgnoreCase(F(AUTOCONNECT_JSON_VALUE_FS)))
         store = AC_File_FS;
       else if (media.equalsIgnoreCase(F(AUTOCONNECT_JSON_VALUE_SD)))
@@ -184,18 +184,18 @@ bool AutoConnectFileJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectFileJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACFILE));
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
-  json.set(F(AUTOCONNECT_JSON_KEY_LABEL), label);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACFILE));
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
+  json[F(AUTOCONNECT_JSON_KEY_LABEL)] = label;
   switch (store) {
   case AC_File_FS:
-    json.set(F(AUTOCONNECT_JSON_KEY_STORE), AUTOCONNECT_JSON_VALUE_FS);
+    json[F(AUTOCONNECT_JSON_KEY_STORE)] = AUTOCONNECT_JSON_VALUE_FS;
     break;
   case AC_File_SD:
-    json.set(F(AUTOCONNECT_JSON_KEY_STORE), AUTOCONNECT_JSON_VALUE_SD);
+    json[F(AUTOCONNECT_JSON_KEY_STORE)] = AUTOCONNECT_JSON_VALUE_SD;
     break;
   case AC_File_Ext:
-    json.set(F(AUTOCONNECT_JSON_KEY_STORE), AUTOCONNECT_JSON_VALUE_EXTERNAL);
+    json[F(AUTOCONNECT_JSON_KEY_STORE)] = AUTOCONNECT_JSON_VALUE_EXTERNAL;
     break;
   }
 }
@@ -215,15 +215,15 @@ size_t AutoConnectInputJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectInputJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACINPUT))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_LABEL)))
-      label = json.get<String>(F(AUTOCONNECT_JSON_KEY_LABEL));
+      label = json[F(AUTOCONNECT_JSON_KEY_LABEL)].as<String>();
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_PATTERN)))
-      pattern = json.get<String>(F(AUTOCONNECT_JSON_KEY_PATTERN));
+      pattern = json[F(AUTOCONNECT_JSON_KEY_PATTERN)].as<String>();
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_PLACEHOLDER)))
-      placeholder = json.get<String>(F(AUTOCONNECT_JSON_KEY_PLACEHOLDER));
+      placeholder = json[F(AUTOCONNECT_JSON_KEY_PLACEHOLDER)].as<String>();
     return true;
   }
   return false;
@@ -235,11 +235,11 @@ bool AutoConnectInputJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectInputJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACINPUT));
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
-  json.set(F(AUTOCONNECT_JSON_KEY_LABEL), label);
-  json.set(F(AUTOCONNECT_JSON_KEY_PATTERN), pattern);
-  json.set(F(AUTOCONNECT_JSON_KEY_PLACEHOLDER), placeholder);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACINPUT));
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
+  json[F(AUTOCONNECT_JSON_KEY_LABEL)] = label;
+  json[F(AUTOCONNECT_JSON_KEY_PATTERN)] = pattern;
+  json[F(AUTOCONNECT_JSON_KEY_PLACEHOLDER)] = placeholder;
 }
 
 /**
@@ -257,15 +257,15 @@ size_t AutoConnectRadioJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectRadioJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACRADIO))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_LABEL)))
-      label = json.get<String>(F(AUTOCONNECT_JSON_KEY_LABEL));
+      label = json[F(AUTOCONNECT_JSON_KEY_LABEL)].as<String>();
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_CHECKED)))
-      checked = static_cast<uint8_t>(json.get<int>(F(AUTOCONNECT_JSON_KEY_CHECKED)));
+      checked = static_cast<uint8_t>(json[F(AUTOCONNECT_JSON_KEY_CHECKED)].as<int>());
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_ARRANGE))) {
-      String  arrange = json.get<String>(F(AUTOCONNECT_JSON_KEY_ARRANGE));
+      String  arrange = json[F(AUTOCONNECT_JSON_KEY_ARRANGE)].as<String>();
       if (arrange.equalsIgnoreCase(F(AUTOCONNECT_JSON_VALUE_VERTICAL)))
         order = AC_Vertical;
       else if (arrange.equalsIgnoreCase(F(AUTOCONNECT_JSON_VALUE_HORIZONTAL)))
@@ -277,7 +277,8 @@ bool AutoConnectRadioJson::loadMember(const JsonObject& json) {
     }
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_VALUE))) {
       empty();
-      JsonArray& optionArray = json[AUTOCONNECT_JSON_KEY_VALUE];
+      // JsonArray& optionArray = json[AUTOCONNECT_JSON_KEY_VALUE];
+      ArduinoJsonArray optionArray = json[AUTOCONNECT_JSON_KEY_VALUE];
       for (auto value : optionArray)
         add(value.as<String>());
     }
@@ -292,20 +293,20 @@ bool AutoConnectRadioJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectRadioJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACRADIO));
-  json.set(F(AUTOCONNECT_JSON_KEY_LABEL), label);
-  JsonArray&  values = json.createNestedArray(F(AUTOCONNECT_JSON_KEY_VALUE));
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACRADIO));
+  json[F(AUTOCONNECT_JSON_KEY_LABEL)] = label;
+  ArduinoJsonArray  values = json.createNestedArray(F(AUTOCONNECT_JSON_KEY_VALUE));
   for (String v : _values)
     values.add(v);
   switch (order) {
   case AC_Horizontal:
-    json.set(F(AUTOCONNECT_JSON_KEY_ARRANGE), AUTOCONNECT_JSON_VALUE_HORIZONTAL);
+    json[F(AUTOCONNECT_JSON_KEY_ARRANGE)] = String(F(AUTOCONNECT_JSON_VALUE_HORIZONTAL));
     break;
   case AC_Vertical:
-    json.set(F(AUTOCONNECT_JSON_KEY_ARRANGE), AUTOCONNECT_JSON_VALUE_VERTICAL);
+    json[F(AUTOCONNECT_JSON_KEY_ARRANGE)] = String(F(AUTOCONNECT_JSON_VALUE_VERTICAL));
     break;
   }
-  json.set(F(AUTOCONNECT_JSON_KEY_CHECKED), checked);
+  json[F(AUTOCONNECT_JSON_KEY_CHECKED)] = checked;
 }
 
 /**
@@ -323,15 +324,15 @@ size_t AutoConnectSelectJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectSelectJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACSELECT))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_LABEL))) {
-      label = json.get<String>(F(AUTOCONNECT_JSON_KEY_LABEL));
+      label = json[F(AUTOCONNECT_JSON_KEY_LABEL)].as<String>();
     }
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_OPTION))) {
       empty();
-      JsonArray& optionArray = json[AUTOCONNECT_JSON_KEY_OPTION];
+      ArduinoJsonArray optionArray = json[AUTOCONNECT_JSON_KEY_OPTION];
       for (auto value : optionArray)
         add(value.as<String>());
       return true;
@@ -346,11 +347,11 @@ bool AutoConnectSelectJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectSelectJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACSELECT));
-  JsonArray&  options = json.createNestedArray(F(AUTOCONNECT_JSON_KEY_OPTION));
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACSELECT));
+  ArduinoJsonArray options = json.createNestedArray(F(AUTOCONNECT_JSON_KEY_OPTION));
   for (String o : _options)
     options.add(o);
-  json.set(F(AUTOCONNECT_JSON_KEY_LABEL), label);
+  json[F(AUTOCONNECT_JSON_KEY_LABEL)] = label;
 }
 
 /**
@@ -368,11 +369,11 @@ size_t AutoConnectSubmitJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectSubmitJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACSUBMIT))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_URI)))
-      uri = json.get<String>(F(AUTOCONNECT_JSON_KEY_URI));
+      uri = json[F(AUTOCONNECT_JSON_KEY_URI)].as<String>();
     return true;
   }
   return false;
@@ -384,9 +385,9 @@ bool AutoConnectSubmitJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectSubmitJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACSUBMIT));
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
-  json.set(F(AUTOCONNECT_JSON_KEY_URI), uri);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACSUBMIT));
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
+  json[F(AUTOCONNECT_JSON_KEY_URI)] = uri;
 }
 
 /**
@@ -404,13 +405,13 @@ size_t AutoConnectTextJson::getObjectSize() const {
  * @return false Type of AutoConnectElement is mismatched.
  */
 bool AutoConnectTextJson::loadMember(const JsonObject& json) {
-  String  type = json.get<String>(F(AUTOCONNECT_JSON_KEY_TYPE));
+  String  type = json[F(AUTOCONNECT_JSON_KEY_TYPE)].as<String>();
   if (type.equalsIgnoreCase(F(AUTOCONNECT_JSON_TYPE_ACTEXT))) {
     _setMember(json);
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_STYLE)))
-      style = json.get<String>(F(AUTOCONNECT_JSON_KEY_STYLE));
+      style = json[F(AUTOCONNECT_JSON_KEY_STYLE)].as<String>();
     if (json.containsKey(F(AUTOCONNECT_JSON_KEY_FORMAT)))
-      format = json.get<String>(F(AUTOCONNECT_JSON_KEY_FORMAT));
+      format = json[F(AUTOCONNECT_JSON_KEY_FORMAT)].as<String>();
     return true;
   }
   return false;
@@ -422,10 +423,10 @@ bool AutoConnectTextJson::loadMember(const JsonObject& json) {
  */
 void AutoConnectTextJson::serialize(JsonObject& json) {
   _serialize(json);
-  json.set(F(AUTOCONNECT_JSON_KEY_TYPE), F(AUTOCONNECT_JSON_TYPE_ACTEXT));
-  json.set(F(AUTOCONNECT_JSON_KEY_VALUE), value);
-  json.set(F(AUTOCONNECT_JSON_KEY_STYLE), style);
-  json.set(F(AUTOCONNECT_JSON_KEY_FORMAT), format);
+  json[F(AUTOCONNECT_JSON_KEY_TYPE)] = String(F(AUTOCONNECT_JSON_TYPE_ACTEXT));
+  json[F(AUTOCONNECT_JSON_KEY_VALUE)] = value;
+  json[F(AUTOCONNECT_JSON_KEY_STYLE)] = style;
+  json[F(AUTOCONNECT_JSON_KEY_FORMAT)] = format;
 }
 
 #endif // _AUTOCONNECTELEMENTJSONIMPL_H_