diff --git a/examples/HelloWorld/HelloWorld.ino b/examples/HelloWorld/HelloWorld.ino
index df4bf7e..d84238a 100644
--- a/examples/HelloWorld/HelloWorld.ino
+++ b/examples/HelloWorld/HelloWorld.ino
@@ -22,14 +22,27 @@ typedef ESP8266WebServer WEBServer;
 #include <SPIFFS.h>
 typedef WebServer WEBServer;
 #endif
-#include <FS.h>
 #include <AutoConnect.h>
 
+/*
+  AC_USE_SPIFFS indicates SPIFFS or LittleFS as available file systems that
+  will become the AUTOCONNECT_USE_SPIFFS identifier and is exported as showng
+  the valid file system. After including AutoConnect.h, the Sketch can determine
+  whether to use FS.h or LittleFS.h by AUTOCONNECT_USE_SPIFFS definition.
+*/
+#ifdef AUTOCONNECT_USE_SPIFFS
+#include <FS.h>
+FS& FlashFS = SPIFFS;
+#else
+#include <LittleFS.h>
+FS& FlashFS = LittleFS;
+#endif
+
 #define HELLO_URI   "/hello"
 #define PARAM_STYLE "/style.json"
 
 // Declare AutoConnectText with only a value.
-// Qualify the Caption by reading style attributes from the SPIFFS style.json file.
+// Qualify the Caption by reading style attributes from the style.json file.
 ACText(Caption, "Hello, world");
 
 //AutoConnectAux for the custom Web page.
@@ -54,15 +67,15 @@ String onHello(AutoConnectAux& aux, PageArgument& args) {
   return String();
 }
 
-// Load the element from specified file in SPIFFS.
+// Load the element from specified file in the flash on board.
 void loadParam(const char* fileName) {
-  SPIFFS.begin();
-  File param = SPIFFS.open(fileName, "r");
+  Flash.begin();
+  File param = FlashFS.open(fileName, "r");
   if (param) {
     ElementJson = param.readString();
     param.close();
   }
-  SPIFFS.end();
+  FlashFS.end();
 }
 
 void setup() {
diff --git a/examples/mqttRSSI/mqttRSSI.ino b/examples/mqttRSSI/mqttRSSI.ino
index d389b31..8862f42 100644
--- a/examples/mqttRSSI/mqttRSSI.ino
+++ b/examples/mqttRSSI/mqttRSSI.ino
@@ -23,10 +23,23 @@ https://opensource.org/licenses/MIT
 #include <HTTPClient.h>
 #define GET_CHIPID()  ((uint16_t)(ESP.getEfuseMac()>>32))
 #endif
-#include <FS.h>
 #include <PubSubClient.h>
 #include <AutoConnect.h>
 
+/*
+  AC_USE_SPIFFS indicates SPIFFS or LittleFS as available file systems that
+  will become the AUTOCONNECT_USE_SPIFFS identifier and is exported as showng
+  the valid file system. After including AutoConnect.h, the Sketch can determine
+  whether to use FS.h or LittleFS.h by AUTOCONNECT_USE_SPIFFS definition.
+*/
+#ifdef AUTOCONNECT_USE_SPIFFS
+#include <FS.h>
+FS& FlashFS = SPIFFS;
+#else
+#include <LittleFS.h>
+FS& FlashFS = LittleFS;
+#endif
+
 #define PARAM_FILE      "/param.json"
 #define AUX_SETTING_URI "/mqtt_setting"
 #define AUX_SAVE_URI    "/mqtt_save"
@@ -253,7 +266,7 @@ void getParams(AutoConnectAux& aux) {
 // elements defined in /mqtt_setting JSON.
 String loadParams(AutoConnectAux& aux, PageArgument& args) {
   (void)(args);
-  File param = SPIFFS.open(PARAM_FILE, "r");
+  File param = FlashFS.open(PARAM_FILE, "r");
   if (param) {
     if (aux.loadElement(param)) {
       getParams(aux);
@@ -287,7 +300,7 @@ String saveParams(AutoConnectAux& aux, PageArgument& args) {
   // 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");
+  File param = FlashFS.open(PARAM_FILE, "w");
   mqtt_setting.saveElement(param, { "mqttserver", "channelid", "userkey", "apikey", "uniqueid", "period", "hostname" });
   param.close();
 
@@ -352,7 +365,7 @@ void setup() {
   delay(1000);
   Serial.begin(115200);
   Serial.println();
-  SPIFFS.begin();
+  FlashFS.begin();
 
   if (portal.load(FPSTR(AUX_mqtt_setting))) {
     AutoConnectAux& mqtt_setting = *portal.aux(AUX_SETTING_URI);
diff --git a/examples/mqttRSSI_FS/mqttRSSI_FS.ino b/examples/mqttRSSI_FS/mqttRSSI_FS.ino
index 1fa1f9f..f736190 100644
--- a/examples/mqttRSSI_FS/mqttRSSI_FS.ino
+++ b/examples/mqttRSSI_FS/mqttRSSI_FS.ino
@@ -29,10 +29,23 @@
 #include <HTTPClient.h>
 #define GET_CHIPID()  ((uint16_t)(ESP.getEfuseMac()>>32))
 #endif
-#include <FS.h>
 #include <PubSubClient.h>
 #include <AutoConnect.h>
 
+/*
+  AC_USE_SPIFFS indicates SPIFFS or LittleFS as available file systems that
+  will become the AUTOCONNECT_USE_SPIFFS identifier and is exported as showng
+  the valid file system. After including AutoConnect.h, the Sketch can determine
+  whether to use FS.h or LittleFS.h by AUTOCONNECT_USE_SPIFFS definition.
+*/
+#ifdef AUTOCONNECT_USE_SPIFFS
+#include <FS.h>
+FS& FlashFS = SPIFFS;
+#else
+#include <LittleFS.h>
+FS& FlashFS = LittleFS;
+#endif
+
 #define PARAM_FILE      "/param.json"
 #define AUX_MQTTSETTING "/mqtt_setting"
 #define AUX_MQTTSAVE    "/mqtt_save"
@@ -110,7 +123,7 @@ int getStrength(uint8_t points) {
 
 String loadParams(AutoConnectAux& aux, PageArgument& args) {
   (void)(args);
-  File param = SPIFFS.open(PARAM_FILE, "r");
+  File param = FlashFS.open(PARAM_FILE, "r");
   if (param) {
     aux.loadElement(param);
     param.close();
@@ -144,7 +157,7 @@ String saveParams(AutoConnectAux& aux, PageArgument& args) {
   // 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");
+  File param = FlashFS.open(PARAM_FILE, "w");
   portal.aux("/mqtt_setting")->saveElement(param, { "mqttserver", "channelid", "userkey", "apikey", "period", "uniqueid", "hostname" });
   param.close();
 
@@ -205,17 +218,17 @@ void handleClearChannel() {
   webServer.client().stop();
 }
 
-// Load AutoConnectAux JSON from SPIFFS.
+// Load AutoConnectAux JSON from the flash on the board.
 bool loadAux(const String auxName) {
   bool  rc = false;
   String  fn = auxName + ".json";
-  File fs = SPIFFS.open(fn.c_str(), "r");
+  File fs = FlashFS.open(fn.c_str(), "r");
   if (fs) {
     rc = portal.load(fs);
     fs.close();
   }
   else
-    Serial.println("SPIFFS open failed: " + fn);
+    Serial.println("Filesystem open failed: " + fn);
   return rc;
 }
 
diff --git a/examples/mqttRSSI_NA/mqttRSSI_NA.ino b/examples/mqttRSSI_NA/mqttRSSI_NA.ino
index 9ffa751..24101ea 100644
--- a/examples/mqttRSSI_NA/mqttRSSI_NA.ino
+++ b/examples/mqttRSSI_NA/mqttRSSI_NA.ino
@@ -23,10 +23,23 @@ https://opensource.org/licenses/MIT
 #include <HTTPClient.h>
 #define GET_CHIPID()  ((uint16_t)(ESP.getEfuseMac()>>32))
 #endif
-#include <FS.h>
 #include <PubSubClient.h>
 #include <AutoConnect.h>
 
+/*
+  AC_USE_SPIFFS indicates SPIFFS or LittleFS as available file systems that
+  will become the AUTOCONNECT_USE_SPIFFS identifier and is exported as showng
+  the valid file system. After including AutoConnect.h, the Sketch can determine
+  whether to use FS.h or LittleFS.h by AUTOCONNECT_USE_SPIFFS definition.
+*/
+#ifdef AUTOCONNECT_USE_SPIFFS
+#include <FS.h>
+FS& FlashFS = SPIFFS;
+#else
+#include <LittleFS.h>
+FS& FlashFS = LittleFS;
+#endif
+
 #define PARAM_FILE      "/param.json"
 #define AUX_SETTING_URI "/mqtt_setting"
 #define AUX_SAVE_URI    "/mqtt_save"
@@ -214,7 +227,7 @@ void setup() {
   delay(1000);
   Serial.begin(115200);
   Serial.println();
-  SPIFFS.begin();
+  FlashFS.begin();
 
   if (uniqueid.checked) {
     config.apid = String("ESP") + "-" + String(GET_CHIPID(), HEX);