   // cache-control 15 seconds
   // add dynamic http resources
   SERVER.on("/fs", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", FILESYSTEM.getStorageDetails());
+    SERVER.send(request, esp8266utils::TEXT_JSON, FILESYSTEM.getStorageDetails());
   });
   SERVER.on("/files", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", FILESYSTEM.getFileListing());
+    SERVER.send(request, esp8266utils::TEXT_JSON, FILESYSTEM.getFileListing());
   });
   SERVER.on("/sta", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", WIFI_STA_CFG.getDetails());
+    SERVER.send(request, esp8266utils::TEXT_JSON, WIFI_STA_CFG.getDetails());
   });
   SERVER.on("/ap", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", WIFI_AP_CFG.getDetails());
+    SERVER.send(request, esp8266utils::TEXT_JSON, WIFI_AP_CFG.getDetails());
   });
   SERVER.on("/esp", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", SYS_CFG.getDetails());
+    SERVER.send(request, esp8266utils::TEXT_JSON, SYS_CFG.getDetails());
   });
   SERVER.on("/motor_a", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", _motorA.getDetails());
+    SERVER.send(request, esp8266utils::TEXT_JSON, _motorA.getDetails());
   });
   SERVER.on("/motor_b", HTTP_GET, [](AsyncWebServerRequest *request) {
-    SERVER.send(request, "text/json", _motorB.getDetails());
+    SERVER.send(request, esp8266utils::TEXT_JSON, _motorB.getDetails());
   });
   // add web socket support
   _wsl.onTextMessage([](AsyncWebSocket *ws, AsyncWebSocketClient *client, AwsEventType type, AwsFrameInfo *info, uint8_t *data, size_t len) {

// web server settings
const static int PORT = 80;

esp8266util::MotorDriver _motorA;
esp8266util::MotorDriver _motorB;

esp8266util::WebSocketListener _wsl;

void setup() {
  // logger setup

  // setup hardware components
  _motorA.begin(MOTOR_A_PWM, MOTOR_A_DIR),
      _motorB.begin(MOTOR_B_PWM, MOTOR_B_DIR),
      esp8266utils::MotorDriver::setPWMRange(PWM_RANGE);

  // WiFi setup
  WIFI_STA_CFG.addAP(WIFI_SSID_1, WIFI_PSK_1);
