diff --git a/code/espurna/button.cpp b/code/espurna/button.cpp
index 6ba233c2..bc716d65 100644
--- a/code/espurna/button.cpp
+++ b/code/espurna/button.cpp
@@ -773,7 +773,7 @@ namespace terminal {
 void button(::terminal::CommandContext&& ctx) {
     if (ctx.argv.size() == 2) {
         size_t id;
-        if (!tryParseId(ctx.argv[1].c_str(), buttonCount, id)) {
+        if (!tryParseId(ctx.argv[1], buttonCount, id)) {
             terminalError(ctx, F("Invalid button ID"));
             return;
         }
@@ -1010,35 +1010,36 @@ namespace {
 
 #if DEBUG_SUPPORT || MQTT_SUPPORT
 
-String _buttonEventString(ButtonEvent event) {
-    const __FlashStringHelper* ptr = nullptr;
+const char* _buttonEventString(ButtonEvent event) {
+    const char* out = "none";
+
     switch (event) {
     case ButtonEvent::Pressed:
-        ptr = F("pressed");
+        out = PSTR("pressed");
         break;
     case ButtonEvent::Released:
-        ptr = F("released");
+        out = PSTR("released");
         break;
     case ButtonEvent::Click:
-        ptr = F("click");
+        out = PSTR("click");
         break;
     case ButtonEvent::DoubleClick:
-        ptr = F("double-click");
+        out = PSTR("double-click");
         break;
     case ButtonEvent::LongClick:
-        ptr = F("long-click");
+        out = PSTR("long-click");
         break;
     case ButtonEvent::LongLongClick:
-        ptr = F("looong-click");
+        out = PSTR("looong-click");
         break;
     case ButtonEvent::TripleClick:
-        ptr = F("triple-click");
+        out = PSTR("triple-click");
         break;
     case ButtonEvent::None:
-        ptr = F("none");
         break;
     }
-    return String(ptr);
+
+    return out;
 }
 
 #endif
@@ -1048,7 +1049,7 @@ String _buttonEventString(ButtonEvent event) {
 void buttonEvent(size_t id, ButtonEvent event) {
 
     DEBUG_MSG_P(PSTR("[BUTTON] Button #%u event %d (%s)\n"),
-        id, static_cast<int>(event), _buttonEventString(event).c_str()
+        id, static_cast<int>(event), _buttonEventString(event)
     );
 
     if (event == ButtonEvent::None) {
@@ -1064,7 +1065,7 @@ void buttonEvent(size_t id, ButtonEvent event) {
 
 #if MQTT_SUPPORT
     if ((action != ButtonAction::None) || _buttons_mqtt_send_all[id]) {
-        mqttSend(MQTT_TOPIC_BUTTON, id, _buttonEventString(event).c_str(), false, _buttons_mqtt_retain[id]);
+        mqttSend(MQTT_TOPIC_BUTTON, id, String(_buttonEventString(event)).c_str(), false, _buttons_mqtt_retain[id]);
     }
 #endif
 
diff --git a/code/espurna/compat.h b/code/espurna/compat.h
index 7b9d81fc..6a7ad58c 100644
--- a/code/espurna/compat.h
+++ b/code/espurna/compat.h
@@ -104,7 +104,7 @@ using std::isnan;
 #endif
 
 // -----------------------------------------------------------------------------
-// std::make_unique & std::clamp backports for C++11, since we still use it
+// various backports for C++11, since we still use it with gcc v4.8
 // -----------------------------------------------------------------------------
 #if __cplusplus <= 201103L
 
@@ -141,6 +141,11 @@ constexpr auto cend(const T& value) -> decltype(std::end(value)) {
     return std::end(value);
 }
 
+template <typename T>
+constexpr std::reverse_iterator<T> make_reverse_iterator(T iterator) {
+    return std::reverse_iterator<T>(iterator);
+}
+
 } // namespace std
 
 #endif
diff --git a/code/espurna/light.cpp b/code/espurna/light.cpp
index 77962cbd..76ca0082 100644
--- a/code/espurna/light.cpp
+++ b/code/espurna/light.cpp
@@ -970,26 +970,27 @@ char _lightTag(size_t channels, size_t index) {
 }
 
 const char* _lightDesc(size_t channels, size_t index) {
-    const __FlashStringHelper* ptr { F("UNKNOWN") };
+    const char* out = PSTR("UNKNOWN");
+
     switch (_lightTag(channels, index)) {
     case 'W':
-        ptr = F("WARM WHITE");
+        out = PSTR("WARM WHITE");
         break;
     case 'C':
-        ptr = F("COLD WHITE");
+        out = PSTR("COLD WHITE");
         break;
     case 'R':
-        ptr = F("RED");
+        out = PSTR("RED");
         break;
     case 'G':
-        ptr = F("GREEN");
+        out = PSTR("GREEN");
         break;
     case 'B':
-        ptr = F("BLUE");
+        out = PSTR("BLUE");
         break;
     }
 
-    return reinterpret_cast<const char*>(ptr);
+    return out;
 }
 
 } // namespace
@@ -1000,15 +1001,15 @@ const char* _lightDesc(size_t channels, size_t index) {
 
 namespace {
 
-void _lightFromHexPayload(const char* payload, size_t len) {
-    const bool JustRgb { (len == 6) };
-    const bool WithBrightness { (len == 8) };
+void _lightFromHexPayload(espurna::StringView payload) {
+    const bool JustRgb { (payload.length() == 6) };
+    const bool WithBrightness { (payload.length() == 8) };
     if (!JustRgb && !WithBrightness) {
         return;
     }
 
     uint8_t values[4] {0, 0, 0, 0};
-    if (hexDecode(payload, len, values, sizeof(values))) {
+    if (hexDecode(payload.begin(), payload.length(), values, sizeof(values))) {
         _light_mapping.red(values[0]);
         _light_mapping.green(values[1]);
         _light_mapping.blue(values[2]);
@@ -1018,11 +1019,11 @@ void _lightFromHexPayload(const char* payload, size_t len) {
     }
 }
 
-void _lightFromCommaSeparatedPayload(const char* payload, size_t len) {
+void _lightFromCommaSeparatedPayload(espurna::StringView payload) {
     constexpr size_t BufferSize { 16 };
-    if (len < BufferSize) {
+    if (payload.length() < BufferSize) {
         char buffer[BufferSize] = {0};
-        std::copy(payload, payload + len, buffer);
+        std::copy(payload.begin(), payload.end(), buffer);
 
         auto it = _light_channels.begin();
         char* tok = std::strtok(buffer, ",");
@@ -1048,28 +1049,27 @@ void _lightFromCommaSeparatedPayload(const char* payload, size_t len) {
     }
 }
 
-void _lightFromRgbPayload(const char* rgb) {
+void _lightFromRgbPayload(espurna::StringView payload) {
     if (!_light_has_color) {
         return;
     }
 
-    if (!rgb || (*rgb == '\0')) {
+    if (!payload.length() || (payload[0] == '\0')) {
         return;
     }
 
-    const size_t PayloadLen { strlen(rgb) };
-
     // HEX value is always prefixed, like CSS
     // - #AABBCC
     // Extra byte is interpreted like RGB + brightness
     // - #AABBCCDD
-    if (rgb[0] == '#') {
-        _lightFromHexPayload(rgb + 1, PayloadLen - 1);
+    if (payload[0] == '#') {
+        _lightFromHexPayload(
+            espurna::StringView(payload.begin() + 1, payload.end()));
         return;
     }
 
     // Otherwise, assume comma-separated decimal values
-    _lightFromCommaSeparatedPayload(rgb, PayloadLen);
+    _lightFromCommaSeparatedPayload(payload);
 }
 
 // HSV string is expected to be "H,S,V", where:
@@ -1077,17 +1077,16 @@ void _lightFromRgbPayload(const char* rgb) {
 // - S [0...100]
 // - V [0...100]
 
-void _lightFromHsvPayload(const char* hsv) {
-    if (!_light_has_color || !hsv || (*hsv == '\0')) {
+void _lightFromHsvPayload(espurna::StringView payload) {
+    if (!_light_has_color || !payload.length() || (payload[0] == '\0')) {
         return;
     }
 
-    const size_t PayloadLen { strlen(hsv) };
     constexpr size_t BufferSize { 16 };
 
-    if (PayloadLen < BufferSize) {
+    if (payload.length() < BufferSize) {
         char buffer[BufferSize] = {0};
-        std::copy(hsv, hsv + PayloadLen, buffer);
+        std::copy(payload.begin(), payload.end(), buffer);
 
         long values[3] {0, 0, 0};
         char* tok = std::strtok(buffer, ",");
@@ -1374,11 +1373,11 @@ String _lightGroupPayload() {
 // Basic value adjustments. Expression can be:
 // +offset, -offset or the new value
 
-long _lightAdjustValue(long value, const String& operation) {
+long _lightAdjustValue(long value, espurna::StringView operation) {
     if (operation.length()) {
         char* endp { nullptr };
-        auto updated = std::strtol(operation.c_str(), &endp, 10);
-        if ((endp == operation.c_str()) || (*endp != '\0')) {
+        auto updated = std::strtol(operation.begin(), &endp, 10);
+        if ((endp == operation.begin()) || (*endp != '\0')) {
             return value;
         }
 
@@ -1394,44 +1393,28 @@ long _lightAdjustValue(long value, const String& operation) {
     return value;
 }
 
-void _lightAdjustBrightness(const String& payload) {
+void _lightAdjustBrightness(espurna::StringView payload) {
     lightBrightness(_lightAdjustValue(_light_brightness, payload));
 }
 
-void _lightAdjustBrightness(const char* payload) {
-    _lightAdjustBrightness(String(payload));
-}
-
-void _lightAdjustChannel(LightChannel& channel, const String& payload) {
+void _lightAdjustChannel(LightChannel& channel, espurna::StringView payload) {
     channel = _lightAdjustValue(channel.inputValue, payload);
 }
 
-void _lightAdjustChannel(size_t id, const String& payload) {
+void _lightAdjustChannel(size_t id, espurna::StringView payload) {
     if (id < _light_channels.size()) {
         _lightAdjustChannel(_light_channels[id], payload);
     }
 }
 
-void _lightAdjustChannel(size_t id, const char* payload) {
-    _lightAdjustChannel(id, String(payload));
-}
-
-void _lightAdjustKelvin(const String& payload) {
+void _lightAdjustKelvin(espurna::StringView payload) {
     _fromKelvin(_lightAdjustValue(_toKelvin(_light_mireds), payload));
 }
 
-void _lightAdjustKelvin(const char* payload) {
-    _lightAdjustKelvin(String(payload));
-}
-
-void _lightAdjustMireds(const String& payload) {
+void _lightAdjustMireds(espurna::StringView payload) {
     _fromMireds(_lightAdjustValue(_light_mireds, payload));
 }
 
-void _lightAdjustMireds(const char* payload) {
-    _lightAdjustMireds(String(payload));
-}
-
 } // namespace
 
 // -----------------------------------------------------------------------------
@@ -2054,8 +2037,8 @@ bool _lightParsePayload(espurna::StringView payload) {
     return true;
 }
 
-bool _lightTryParseChannel(const char* p, size_t& id) {
-    return tryParseId(p, lightChannels, id);
+bool _lightTryParseChannel(espurna::StringView value, size_t& id) {
+    return tryParseId(value, lightChannels, id);
 }
 
 } // namespace
@@ -2190,12 +2173,10 @@ void _lightMqttCallback(unsigned int type, const char* topic, char* payload) {
         // Channel
         if (t.startsWith(MQTT_TOPIC_CHANNEL)) {
             size_t id;
-            if (!_lightTryParseChannel(t.c_str() + strlen(MQTT_TOPIC_CHANNEL) + 1, id)) {
-                return;
+            if (_lightTryParseChannel(mqttMagnitudeTail(t, MQTT_TOPIC_CHANNEL), id)) {
+                _lightAdjustChannel(id, payload);
+                _lightUpdateFromMqtt();
             }
-
-            _lightAdjustChannel(id, payload);
-            _lightUpdateFromMqtt();
             return;
         }
 
@@ -2258,9 +2239,10 @@ namespace {
 
 template <typename T>
 bool _lightApiTryHandle(ApiRequest& request, T&& callback) {
-    auto id_param = request.wildcard(0);
+    const auto param = request.wildcard(0);
+
     size_t id;
-    if (!_lightTryParseChannel(id_param.c_str(), id)) {
+    if (!_lightTryParseChannel(param, id)) {
         return false;
     }
 
@@ -2268,7 +2250,7 @@ bool _lightApiTryHandle(ApiRequest& request, T&& callback) {
 }
 
 bool _lightApiRgbSetter(ApiRequest& request) {
-    lightColor(request.param(F("value")), true);
+    lightParseRgb(request.param(F("value")));
     lightUpdate();
     return true;
 }
@@ -2297,7 +2279,7 @@ void _lightApiSetup() {
                 return true;
             },
             [](ApiRequest& request) {
-                lightColor(request.param(F("value")), false);
+                lightParseHsv(request.param(F("value")));
                 lightUpdate();
                 return true;
             }
@@ -2458,31 +2440,42 @@ void _lightWebSocketOnConnected(JsonObject& root) {
 }
 
 void _lightWebSocketOnAction(uint32_t client_id, const char* action, JsonObject& data) {
+    STRING_VIEW_INLINE(Color, "color");
+
     if (_light_has_color) {
-        if (STRING_VIEW("color") == action) {
-            if (data.containsKey(F("rgb"))) {
-                _lightFromRgbPayload(data[F("rgb")].as<const char*>());
+        if (Color == action) {
+            STRING_VIEW_INLINE(Rgb, "rgb");
+            STRING_VIEW_INLINE(Hsv, "hsv");
+
+            if (data.containsKey(Rgb)) {
+                _lightFromRgbPayload(data[Rgb].as<espurna::StringView>());
                 lightUpdate();
-            } else if (data.containsKey("hsv")) {
-                _lightFromHsvPayload(data[F("hsv")].as<const char*>());
+            } else if (data.containsKey(Hsv)) {
+                _lightFromHsvPayload(data[Hsv].as<espurna::StringView>());
                 lightUpdate();
             }
         }
     }
 
-    if (STRING_VIEW("mireds") == action) {
-        if (data.containsKey(F("mireds"))) {
-            _fromMireds(data[F("mireds")].as<long>());
+    STRING_VIEW_INLINE(Mireds, "mireds");
+    STRING_VIEW_INLINE(Brightness, "brightness");
+    STRING_VIEW_INLINE(Id, "id");
+    STRING_VIEW_INLINE(Channel, "channel");
+    STRING_VIEW_INLINE(Value, "value");
+
+    if (Mireds == action) {
+        if (data.containsKey(Mireds)) {
+            _fromMireds(data[Mireds].as<long>());
             lightUpdate();
         }
-    } else if (STRING_VIEW("channel") == action) {
-        if (data.containsKey(F("id")) && data.containsKey(F("value"))) {
-            lightChannel(data[F("id")].as<size_t>(), data[F("value")].as<long>());
+    } else if (Channel == action) {
+        if (data.containsKey(Id) && data.containsKey(Value)) {
+            lightChannel(data[Id].as<size_t>(), data[Value].as<long>());
             lightUpdate();
         }
-    } else if (STRING_VIEW("brightness") == action) {
-        if (data.containsKey(F("value"))) {
-            lightBrightness(data[F("value")].as<long>());
+    } else if (Brightness == action) {
+        if (data.containsKey(Value)) {
+            lightBrightness(data[Value].as<long>());
             lightUpdate();
         }
     }
@@ -2557,7 +2550,7 @@ static void _lightCommandNotify(::terminal::CommandContext&& ctx) {
     }
 
     size_t channel;
-    if (!_lightTryParseChannel(ctx.argv[1].c_str(), channel)) {
+    if (!_lightTryParseChannel(ctx.argv[1], channel)) {
         terminalError(ctx, F("Invalid channel ID"));
         return;
     }
@@ -2649,7 +2642,8 @@ static void _lightCommandChannel(::terminal::CommandContext&& ctx) {
 
     auto description = [&](size_t channel) {
         ctx.output.printf_P(PSTR("#%zu (%s) input:%ld value:%ld target:%ld current:%s\n"),
-                channel, _lightDesc(Channels, channel),
+                channel,
+                _lightDesc(Channels, channel),
                 _light_channels[channel].inputValue,
                 _light_channels[channel].value,
                 _light_channels[channel].target,
@@ -2658,7 +2652,7 @@ static void _lightCommandChannel(::terminal::CommandContext&& ctx) {
 
     if (ctx.argv.size() > 2) {
         size_t id;
-        if (!_lightTryParseChannel(ctx.argv[1].c_str(), id)) {
+        if (!_lightTryParseChannel(ctx.argv[1], id)) {
             terminalError(ctx, F("Invalid channel ID"));
             return;
         }
@@ -2679,7 +2673,7 @@ alignas(4) static constexpr char LightCommandRgb[] PROGMEM = "RGB";
 
 static void _lightCommandRgb(::terminal::CommandContext&& ctx) {
     if (ctx.argv.size() > 1) {
-        _lightFromRgbPayload(ctx.argv[1].c_str());
+        _lightFromRgbPayload(ctx.argv[1]);
         lightUpdate();
     }
 
@@ -2692,7 +2686,7 @@ alignas(4) static constexpr char LightCommandHsv[] PROGMEM = "HSV";
 
 static void _lightCommandHsv(::terminal::CommandContext&& ctx) {
     if (ctx.argv.size() > 1) {
-        _lightFromHsvPayload(ctx.argv[1].c_str());
+        _lightFromHsvPayload(ctx.argv[1]);
         lightUpdate();
     }
 
@@ -3081,25 +3075,12 @@ bool lightState() {
     return _light_state;
 }
 
-void lightColor(const char* color, bool rgb) {
-    DEBUG_MSG_P(PSTR("[LIGHT] %s: %s\n"), rgb ? "RGB" : "HSV", color);
-    if (rgb) {
-        _lightFromRgbPayload(color);
-    } else {
-        _lightFromHsvPayload(color);
-    }
+void lightParseHsv(espurna::StringView value) {
+    _lightFromHsvPayload(value);
 }
 
-void lightColor(const String& color, bool rgb) {
-    lightColor(color.c_str(), rgb);
-}
-
-void lightColor(const char* color) {
-    lightColor(color, true);
-}
-
-void lightColor(const String& color) {
-    lightColor(color.c_str());
+void lightParseRgb(espurna::StringView value) {
+    _lightFromRgbPayload(value);
 }
 
 String lightRgbPayload() {
diff --git a/code/espurna/light.h b/code/espurna/light.h
index 7a754a27..3ec4ac04 100644
--- a/code/espurna/light.h
+++ b/code/espurna/light.h
@@ -202,11 +202,8 @@ using LightSequenceCallbacks = std::forward_list<espurna::Callback>;
 void lightSequence(LightSequenceCallbacks);
 void lightUpdateSequence(LightTransition);
 
-void lightColor(const char* color, bool rgb);
-void lightColor(const String& color, bool rgb);
-
-void lightColor(const char* color);
-void lightColor(const String& color);
+void lightParseHsv(espurna::StringView);
+void lightParseRgb(espurna::StringView);
 
 String lightRgbPayload();
 String lightHsvPayload();
diff --git a/code/espurna/mqtt.cpp b/code/espurna/mqtt.cpp
index b16c8f84..edc91ba6 100644
--- a/code/espurna/mqtt.cpp
+++ b/code/espurna/mqtt.cpp
@@ -1274,6 +1274,11 @@ String mqttMagnitude(const char* topic) {
     return output;
 }
 
+// Retrieve lefthand side of the extracted magnitude value
+espurna::StringView mqttMagnitudeTail(espurna::StringView magnitude, espurna::StringView topic) {
+    return espurna::StringView(magnitude.begin() + topic.length(), magnitude.end());
+}
+
 /**
     Returns a full MQTT topic from the magnitude
 
diff --git a/code/espurna/mqtt.h b/code/espurna/mqtt.h
index a17a4eca..06fc5f0f 100644
--- a/code/espurna/mqtt.h
+++ b/code/espurna/mqtt.h
@@ -70,6 +70,7 @@ String mqttTopic(const String& magnitude, unsigned int index, bool is_set);
 String mqttTopic(const char* magnitude, unsigned int index, bool is_set);
 
 String mqttMagnitude(const char* topic);
+espurna::StringView mqttMagnitudeTail(espurna::StringView magnitude, espurna::StringView topic);
 
 uint16_t mqttSendRaw(const char * topic, const char * message, bool retain, int qos);
 uint16_t mqttSendRaw(const char * topic, const char * message, bool retain);
diff --git a/code/espurna/relay.cpp b/code/espurna/relay.cpp
index 275ecfb4..5eb82684 100644
--- a/code/espurna/relay.cpp
+++ b/code/espurna/relay.cpp
@@ -217,41 +217,33 @@ constexpr RelayMqttTopicMode mqttTopicMode(size_t index) {
     );
 }
 
-const __FlashStringHelper* payloadOn() {
-    return F(RELAY_MQTT_ON);
-}
+alignas(4) static constexpr char PayloadOn[] PROGMEM = RELAY_MQTT_ON;
+alignas(4) static constexpr char PayloadOff[] PROGMEM = RELAY_MQTT_OFF;
+alignas(4) static constexpr char PayloadToggle[] PROGMEM = RELAY_MQTT_TOGGLE;
 
-const __FlashStringHelper* payloadOff() {
-    return F(RELAY_MQTT_OFF);
-}
-
-const __FlashStringHelper* payloadToggle() {
-    return F(RELAY_MQTT_TOGGLE);
-}
-
-constexpr const char* mqttTopicSub(size_t index) {
+constexpr espurna::StringView mqttTopicSub(size_t index) {
     return (
-        (index == 0) ? (RELAY1_MQTT_TOPIC_SUB) :
-        (index == 1) ? (RELAY2_MQTT_TOPIC_SUB) :
-        (index == 2) ? (RELAY3_MQTT_TOPIC_SUB) :
-        (index == 3) ? (RELAY4_MQTT_TOPIC_SUB) :
-        (index == 4) ? (RELAY5_MQTT_TOPIC_SUB) :
-        (index == 5) ? (RELAY6_MQTT_TOPIC_SUB) :
-        (index == 6) ? (RELAY7_MQTT_TOPIC_SUB) :
-        (index == 7) ? (RELAY8_MQTT_TOPIC_SUB) : ""
+        (index == 0) ? STRING_VIEW(RELAY1_MQTT_TOPIC_SUB) :
+        (index == 1) ? STRING_VIEW(RELAY2_MQTT_TOPIC_SUB) :
+        (index == 2) ? STRING_VIEW(RELAY3_MQTT_TOPIC_SUB) :
+        (index == 3) ? STRING_VIEW(RELAY4_MQTT_TOPIC_SUB) :
+        (index == 4) ? STRING_VIEW(RELAY5_MQTT_TOPIC_SUB) :
+        (index == 5) ? STRING_VIEW(RELAY6_MQTT_TOPIC_SUB) :
+        (index == 6) ? STRING_VIEW(RELAY7_MQTT_TOPIC_SUB) :
+        (index == 7) ? STRING_VIEW(RELAY8_MQTT_TOPIC_SUB) : ""
     );
 }
 
-constexpr const char* mqttTopicPub(size_t index) {
+constexpr espurna::StringView mqttTopicPub(size_t index) {
     return (
-        (index == 0) ? (RELAY1_MQTT_TOPIC_PUB) :
-        (index == 1) ? (RELAY2_MQTT_TOPIC_PUB) :
-        (index == 2) ? (RELAY3_MQTT_TOPIC_PUB) :
-        (index == 3) ? (RELAY4_MQTT_TOPIC_PUB) :
-        (index == 4) ? (RELAY5_MQTT_TOPIC_PUB) :
-        (index == 5) ? (RELAY6_MQTT_TOPIC_PUB) :
-        (index == 6) ? (RELAY7_MQTT_TOPIC_PUB) :
-        (index == 7) ? (RELAY8_MQTT_TOPIC_PUB) : ""
+        (index == 0) ? STRING_VIEW(RELAY1_MQTT_TOPIC_PUB) :
+        (index == 1) ? STRING_VIEW(RELAY2_MQTT_TOPIC_PUB) :
+        (index == 2) ? STRING_VIEW(RELAY3_MQTT_TOPIC_PUB) :
+        (index == 3) ? STRING_VIEW(RELAY4_MQTT_TOPIC_PUB) :
+        (index == 4) ? STRING_VIEW(RELAY5_MQTT_TOPIC_PUB) :
+        (index == 5) ? STRING_VIEW(RELAY6_MQTT_TOPIC_PUB) :
+        (index == 6) ? STRING_VIEW(RELAY7_MQTT_TOPIC_PUB) :
+        (index == 7) ? STRING_VIEW(RELAY8_MQTT_TOPIC_PUB) : ""
     );
 }
 
@@ -872,17 +864,17 @@ RelaySync syncMode() {
 
 [[gnu::unused]]
 String payloadOn() {
-    return getSetting(keys::PayloadOn, build::payloadOn());
+    return getSetting(keys::PayloadOn, StringView(build::PayloadOn));
 }
 
 [[gnu::unused]]
 String payloadOff() {
-    return getSetting(keys::PayloadOff, build::payloadOff());
+    return getSetting(keys::PayloadOff, StringView(build::PayloadOff));
 }
 
 [[gnu::unused]]
 String payloadToggle() {
-    return getSetting(keys::PayloadToggle, build::payloadToggle());
+    return getSetting(keys::PayloadToggle, StringView(build::PayloadToggle));
 }
 
 #if MQTT_SUPPORT
@@ -1466,24 +1458,27 @@ Stream* StmProvider::_port = nullptr;
 // UTILITY
 // -----------------------------------------------------------------------------
 
-bool _relayTryParseId(const char* p, size_t& id) {
-    return tryParseId(p, relayCount, id);
+bool _relayTryParseId(espurna::StringView value, size_t& id) {
+    return tryParseId(value, relayCount, id);
 }
 
 [[gnu::unused]]
-bool _relayTryParseIdFromPath(const String& endpoint, size_t& id) {
-    int next_slash { endpoint.lastIndexOf('/') };
-    if (next_slash < 0) {
+bool _relayTryParseIdFromPath(espurna::StringView endpoint, size_t& id) {
+    const auto begin = std::make_reverse_iterator(endpoint.end());
+    const auto end = std::make_reverse_iterator(endpoint.begin());
+
+    auto next_slash = std::find(begin, end, '/');
+    if (next_slash == end) {
         return false;
     }
 
-    const char* p { endpoint.c_str() + next_slash + 1 };
-    if (*p == '\0') {
+    espurna::StringView tail { next_slash.base() + 1, endpoint.end() };
+    if ((*tail.begin()) == '\0') {
         DEBUG_MSG_P(PSTR("[RELAY] relayID was not specified\n"));
         return false;
     }
 
-    return _relayTryParseId(p, id);
+    return _relayTryParseId(tail, id);
 }
 
 void _relayHandleStatus(size_t id, PayloadStatus status) {
@@ -2201,9 +2196,10 @@ namespace {
 
 template <typename T>
 bool _relayApiTryHandle(ApiRequest& request, T&& callback) {
-    auto id_param = request.wildcard(0);
+    const auto param = request.wildcard(0);
+
     size_t id;
-    if (!_relayTryParseId(id_param.c_str(), id)) {
+    if (!_relayTryParseId(param, id)) {
         return false;
     }
 
@@ -2514,7 +2510,7 @@ void relayMQTTCallback(unsigned int type, const char* topic, char* payload) {
         auto is_pulse = t.startsWith(MQTT_TOPIC_PULSE);
         if (is_relay || is_pulse) {
             size_t id;
-            if (!_relayTryParseIdFromPath(t.c_str(), id)) {
+            if (!_relayTryParseIdFromPath(t, id)) {
                 return;
             }
 
@@ -2591,7 +2587,7 @@ static void _relayCommand(::terminal::CommandContext&& ctx) {
     }
 
     size_t id;
-    if (!_relayTryParseId(ctx.argv[1].c_str(), id)) {
+    if (!_relayTryParseId(ctx.argv[1], id)) {
         terminalError(ctx, F("Invalid relayID"));
         return;
     }
@@ -2622,7 +2618,7 @@ static void _relayCommandPulse(::terminal::CommandContext&& ctx) {
     }
 
     size_t id;
-    if (!_relayTryParseId(ctx.argv[1].c_str(), id)) {
+    if (!_relayTryParseId(ctx.argv[1], id)) {
         terminalError(ctx, F("Invalid relayID"));
         return;
     }
diff --git a/code/espurna/rfbridge.cpp b/code/espurna/rfbridge.cpp
index 06fdb7fa..8649bc9d 100644
--- a/code/espurna/rfbridge.cpp
+++ b/code/espurna/rfbridge.cpp
@@ -524,13 +524,13 @@ RfbRelayMatch _rfbMatch(const char* code) {
                 return;
             }
 
-            const char* id_ptr = key.c_str() + prefix.length();
-            if (*id_ptr == '\0') {
+            espurna::StringView id_view(key.begin() + prefix.length(), key.end());
+            if (!id_view.length() || (*id_view.begin()) == '\0') {
                 return;
             }
 
             size_t id;
-            if (!tryParseId(id_ptr, relayCount, id)) {
+            if (!tryParseId(id_view, relayCount, id)) {
                 return;
             }
 
@@ -1185,7 +1185,7 @@ static void _rfbCommandLearn(::terminal::CommandContext&& ctx) {
     }
 
     size_t id;
-    if (!tryParseId(ctx.argv[1].c_str(), relayCount, id)) {
+    if (!tryParseId(ctx.argv[1], relayCount, id)) {
         terminalError(ctx, F("Invalid relay ID"));
         return;
     }
@@ -1202,7 +1202,7 @@ static void _rfbCommandForget(::terminal::CommandContext&& ctx) {
     }
 
     size_t id;
-    if (!tryParseId(ctx.argv[1].c_str(), relayCount, id)) {
+    if (!tryParseId(ctx.argv[1], relayCount, id)) {
         terminalError(ctx, F("Invalid relay ID"));
         return;
     }
diff --git a/code/espurna/rpnrules.cpp b/code/espurna/rpnrules.cpp
index 1ad1eaf7..9bba5bb4 100644
--- a/code/espurna/rpnrules.cpp
+++ b/code/espurna/rpnrules.cpp
@@ -763,8 +763,17 @@ void init(rpn_context& context) {
         return 0;
     });
 
-    rpn_operator_set(context, "black", 0, [](rpn_context& ctxt) -> rpn_error {
-        ::lightColor(0ul);
+    rpn_operator_set(context, "brightness", 0, [](rpn_context& ctxt) -> rpn_error {
+        rpn_value value { static_cast<rpn_int>(::lightBrightness()) };
+        rpn_stack_push(ctxt, value);
+        return 0;
+    });
+
+    rpn_operator_set(context, "set_brightness", 1, [](rpn_context& ctxt) -> rpn_error {
+        rpn_value value;
+        rpn_stack_pop(ctxt, value);
+
+        ::lightBrightness(value.toInt());
         return 0;
     });
 
diff --git a/code/espurna/scheduler.cpp b/code/espurna/scheduler.cpp
index 5f0baa7e..d52ff9e6 100644
--- a/code/espurna/scheduler.cpp
+++ b/code/espurna/scheduler.cpp
@@ -532,8 +532,10 @@ bool set(ApiRequest&, JsonObject& root) {
 namespace schedule {
 
 bool get(ApiRequest& req, JsonObject& root) {
+    const auto param = req.wildcard(0);
+
     size_t id;
-    if (tryParseId(req.wildcard(0).c_str(), build::max, id)) {
+    if (tryParseId(param, build::max, id)) {
         print(root, settings::schedule(id));
         return true;
     }
@@ -542,8 +544,10 @@ bool get(ApiRequest& req, JsonObject& root) {
 }
 
 bool set(ApiRequest& req, JsonObject& root) {
+    const auto param = req.wildcard(0);
+
     size_t id;
-    if (tryParseId(req.wildcard(0).c_str(), build::max, id)) {
+    if (tryParseId(param, build::max, id)) {
         return api::set(root, id);
     }
 
diff --git a/code/espurna/types.h b/code/espurna/types.h
index 420813b7..e59760dd 100644
--- a/code/espurna/types.h
+++ b/code/espurna/types.h
@@ -209,7 +209,7 @@ private:
 };
 
 struct StringView {
-    StringView() = delete;
+    StringView() noexcept = default;
     ~StringView() = default;
 
     constexpr StringView(const StringView&) noexcept = default;
@@ -251,7 +251,6 @@ struct StringView {
         _len(0)
     {}
 
-    StringView(const String&&) = delete;
     StringView(const String& string) noexcept :
         StringView(string.c_str(), string.length())
     {}
@@ -281,6 +280,10 @@ struct StringView {
         return _ptr;
     }
 
+    constexpr const char& operator[](size_t offset) const {
+        return *(_ptr + offset);
+    }
+
     constexpr size_t length() const {
         return _len;
     }
@@ -340,4 +343,8 @@ inline String operator+=(String& lhs, StringView rhs) {
         ::espurna::StringView{__pstr__};\
     })
 
+#define STRING_VIEW_INLINE(NAME, X)\
+        alignas(4) static constexpr char __pstr__ ## NAME ##  __ [] PROGMEM = (X);\
+        constexpr auto NAME = ::espurna::StringView(__pstr__ ## NAME ## __)
+
 } // namespace espurna
diff --git a/code/espurna/utils.cpp b/code/espurna/utils.cpp
index 52ef3bf6..bae8c66e 100644
--- a/code/espurna/utils.cpp
+++ b/code/espurna/utils.cpp
@@ -13,12 +13,12 @@ Copyright (C) 2017-2019 by Xose Pérez <xose dot perez at gmail dot com>
 #include <limits>
 #include <random>
 
-bool tryParseId(const char* p, TryParseIdFunc limit, size_t& out) {
+bool tryParseId(espurna::StringView value, TryParseIdFunc limit, size_t& out) {
     static_assert(std::numeric_limits<size_t>::max() >= std::numeric_limits<unsigned long>::max(), "");
 
     char* endp { nullptr };
-    out = strtoul(p, &endp, 10);
-    if ((endp == p) || (*endp != '\0') || (out >= limit())) {
+    out = strtoul(value.begin(), &endp, 10); // TODO from_chars
+    if ((endp == value.begin()) || (*endp != '\0') || (out >= limit())) {
         return false;
     }
 
diff --git a/code/espurna/utils.h b/code/espurna/utils.h
index 5ad10782..1be39683 100644
--- a/code/espurna/utils.h
+++ b/code/espurna/utils.h
@@ -51,6 +51,6 @@ uint8_t* hexDecode(const char* in_begin, const char* in_end, uint8_t* out_begin,
 size_t hexDecode(const char* in, size_t in_size, uint8_t* out, size_t out_size);
 
 using TryParseIdFunc = size_t(*)();
-bool tryParseId(const char* ptr, TryParseIdFunc limit, size_t& out);
+bool tryParseId(espurna::StringView, TryParseIdFunc limit, size_t& out);
 
 espurna::StringView stripNewline(espurna::StringView);
diff --git a/code/espurna/wifi.cpp b/code/espurna/wifi.cpp
index d1f4a8ea..b2c86039 100644
--- a/code/espurna/wifi.cpp
+++ b/code/espurna/wifi.cpp
@@ -2526,32 +2526,45 @@ String event(wifi::Event value) {
 
 [[gnu::unused]]
 const char* state(wifi::State value) {
+    const char* out = "?";
+
     switch (value) {
     case wifi::State::Boot:
-        return "Boot";
+        out = PSTR("Boot");
+        break;
     case wifi::State::Connect:
-        return "Connect";
+        out = PSTR("Connect");
+        break;
     case wifi::State::TryConnectBetter:
-        return "TryConnectBetter";
+        out = PSTR("TryConnectBetter");
+        break;
     case wifi::State::Fallback:
-        return "Fallback";
+        out = PSTR("Fallback");
+        break;
     case wifi::State::Connected:
-        return "Connected";
+        out = PSTR("Connected");
+        break;
     case wifi::State::Idle:
-        return "Idle";
+        out = PSTR("Idle");
+        break;
     case wifi::State::Init:
-        return "Init";
+        out = PSTR("Init");
+        break;
     case wifi::State::Timeout:
-        return "Timeout";
+        out = PSTR("Timeout");
+        break;
     case wifi::State::WaitScan:
-        return "WaitScan";
+        out = PSTR("WaitScan");
+        break;
     case wifi::State::WaitScanWithoutCurrent:
-        return "WaitScanWithoutCurrent";
+        out = PSTR("WaitScanWithoutCurrent");
+        break;
     case wifi::State::WaitConnected:
-        return "WaitConnected";
+        out = PSTR("WaitConnected");
+        break;
     }
 
-    return "";
+    return out;
 }
 
 } // namespace debug