diff --git a/code/espurna/alexa.cpp b/code/espurna/alexa.cpp
index e59440ab..073673e7 100644
--- a/code/espurna/alexa.cpp
+++ b/code/espurna/alexa.cpp
@@ -108,8 +108,8 @@ void _alexaWebSocketOnVisible(JsonObject& root) {
     wsPayloadModule(root, PSTR("alexa"));
 }
 
-bool _alexaWebSocketOnKeyCheck(const char * key, JsonVariant&) {
-    return (strncmp_P(key, PSTR("alexa"), 5) == 0);
+bool _alexaWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("alexa"));
 }
 
 void _alexaWebSocketOnConnected(JsonObject& root) {
diff --git a/code/espurna/api_common.cpp b/code/espurna/api_common.cpp
index 9f586f82..57af66ab 100644
--- a/code/espurna/api_common.cpp
+++ b/code/espurna/api_common.cpp
@@ -20,8 +20,8 @@ Copyright (C) 2020 by Maxim Prokhorov <prokhorov dot max at outlook dot com>
 
 namespace {
 
-bool _apiWebSocketOnKeyCheck(const char * key, JsonVariant&) {
-    return (strncmp_P(key, PSTR("api"), 3) == 0);
+bool _apiWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("api"));
 }
 
 void _apiWebSocketOnVisible(JsonObject& root) {
diff --git a/code/espurna/button.cpp b/code/espurna/button.cpp
index d0e2bf68..0af69449 100644
--- a/code/espurna/button.cpp
+++ b/code/espurna/button.cpp
@@ -567,12 +567,12 @@ template <typename T>
 T indexedThenGlobal(const String& prefix, size_t index, T defaultValue) {
     const auto key = espurna::settings::Key{prefix, index};
 
-    auto indexed = espurna::settings::internal::get(key.value());
+    const auto indexed = espurna::settings::get(key.value());
     if (indexed) {
         return espurna::settings::internal::convert<T>(indexed.ref());
     }
 
-    auto global = espurna::settings::internal::get(prefix);
+    const auto global = espurna::settings::get(prefix);
     if (global) {
         return espurna::settings::internal::convert<T>(indexed.ref());
     }
@@ -749,8 +749,7 @@ static constexpr espurna::settings::query::IndexedSetting IndexedSettings[] PROG
 };
 
 bool checkSamePrefix(StringView key) {
-    alignas(4) static constexpr char Prefix[] PROGMEM = "btn";
-    return espurna::settings::query::samePrefix(key, Prefix);
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("btn"));
 }
 
 String findValueFrom(StringView key) {
@@ -940,8 +939,8 @@ void _buttonWebSocketOnConnected(JsonObject& root) {
     }
 }
 
-bool _buttonWebSocketOnKeyCheck(const char * key, JsonVariant&) {
-    return (strncmp_P(key, PSTR("btn"), 3) == 0);
+bool _buttonWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::button::settings::query::checkSamePrefix(key);
 }
 
 } // namespace
diff --git a/code/espurna/curtain_kingart.cpp b/code/espurna/curtain_kingart.cpp
index 06edb2a6..2dc88f96 100644
--- a/code/espurna/curtain_kingart.cpp
+++ b/code/espurna/curtain_kingart.cpp
@@ -394,9 +394,8 @@ void _curtainWebSocketOnConnected(JsonObject& root) {
 }
 
 //------------------------------------------------------------------------------
-bool _curtainWebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    if (strncmp_P(key, PSTR("curtain"), __builtin_strlen("curtain")) == 0) return true;
-    return false;
+bool _curtainWebSocketOnKeyCheck(const char * key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("curtain"));
 }
 
 //------------------------------------------------------------------------------
diff --git a/code/espurna/domoticz.cpp b/code/espurna/domoticz.cpp
index 942a868b..e0baa16c 100644
--- a/code/espurna/domoticz.cpp
+++ b/code/espurna/domoticz.cpp
@@ -434,8 +434,8 @@ namespace {
 
 alignas(4) static constexpr char Prefix[] PROGMEM = "dcz";
 
-bool onKeyCheck(const char* key, JsonVariant& value) {
-    return (strncmp_P(key, Prefix, 3) == 0);
+bool onKeyCheck(const char* key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, Prefix);
 }
 
 void onVisible(JsonObject& root) {
diff --git a/code/espurna/garland.cpp b/code/espurna/garland.cpp
index 59b79490..0c6c9b55 100644
--- a/code/espurna/garland.cpp
+++ b/code/espurna/garland.cpp
@@ -65,29 +65,29 @@ namespace {
 #include "garland/palette.h"
 #include "garland/scene.h"
 
-const char* const NAME_GARLAND_ENABLED        = "garlandEnabled";
-const char* const NAME_GARLAND_BRIGHTNESS     = "garlandBrightness";
-const char* const NAME_GARLAND_SPEED          = "garlandSpeed";
+alignas(4) static constexpr char NAME_GARLAND_ENABLED[] = "garlandEnabled";
+alignas(4) static constexpr char NAME_GARLAND_BRIGHTNESS[] = "garlandBrightness";
+alignas(4) static constexpr char NAME_GARLAND_SPEED[] = "garlandSpeed";
 
-const char* const NAME_GARLAND_SWITCH         = "garland_switch";
-const char* const NAME_GARLAND_SET_BRIGHTNESS = "garland_set_brightness";
-const char* const NAME_GARLAND_SET_SPEED      = "garland_set_speed";
-const char* const NAME_GARLAND_SET_DEFAULT    = "garland_set_default";
+alignas(4) static constexpr char NAME_GARLAND_SWITCH[] = "garland_switch";
+alignas(4) static constexpr char NAME_GARLAND_SET_BRIGHTNESS[] = "garland_set_brightness";
+alignas(4) static constexpr char NAME_GARLAND_SET_SPEED[] = "garland_set_speed";
+alignas(4) static constexpr char NAME_GARLAND_SET_DEFAULT[] = "garland_set_default";
 
-const char* const MQTT_TOPIC_GARLAND          = "garland";
+alignas(4) static constexpr char MQTT_TOPIC_GARLAND[] = "garland";
 
-const char* const MQTT_PAYLOAD_COMMAND        = "command";
-const char* const MQTT_PAYLOAD_ENABLE         = "enable";
-const char* const MQTT_PAYLOAD_BRIGHTNESS     = "brightness";
-const char* const MQTT_PAYLOAD_ANIM_SPEED     = "speed";
-const char* const MQTT_PAYLOAD_ANIMATION      = "animation";
-const char* const MQTT_PAYLOAD_PALETTE        = "palette";
-const char* const MQTT_PAYLOAD_DURATION       = "duration";
+alignas(4) static constexpr char MQTT_PAYLOAD_COMMAND[] = "command";
+alignas(4) static constexpr char MQTT_PAYLOAD_ENABLE[] = "enable";
+alignas(4) static constexpr char MQTT_PAYLOAD_BRIGHTNESS[] = "brightness";
+alignas(4) static constexpr char MQTT_PAYLOAD_ANIM_SPEED[] = "speed";
+alignas(4) static constexpr char MQTT_PAYLOAD_ANIMATION[] = "animation";
+alignas(4) static constexpr char MQTT_PAYLOAD_PALETTE[] = "palette";
+alignas(4) static constexpr char MQTT_PAYLOAD_DURATION[] = "duration";
 
-const char* const MQTT_COMMAND_IMMEDIATE      = "immediate";
-const char* const MQTT_COMMAND_RESET          = "reset"; // reset queue
-const char* const MQTT_COMMAND_QUEUE          = "queue"; // enqueue command payload
-const char* const MQTT_COMMAND_SEQUENCE       = "sequence"; // place command to sequence
+alignas(4) static constexpr char MQTT_COMMAND_IMMEDIATE[] = "immediate";
+alignas(4) static constexpr char MQTT_COMMAND_RESET[] = "reset"; // reset queue
+alignas(4) static constexpr char MQTT_COMMAND_QUEUE[] = "queue"; // enqueue command payload
+alignas(4) static constexpr char MQTT_COMMAND_SEQUENCE[] = "sequence"; // place command to sequence
 
 #define EFFECT_UPDATE_INTERVAL_MIN      7000  // 5 sec
 #define EFFECT_UPDATE_INTERVAL_MAX      12000 // 10 sec
@@ -219,11 +219,10 @@ void _garlandWebSocketOnConnected(JsonObject& root) {
 }
 
 //------------------------------------------------------------------------------
-bool _garlandWebSocketOnKeyCheck(const char* key, JsonVariant& value) {
-    if (strncmp(key, NAME_GARLAND_ENABLED, strlen(NAME_GARLAND_ENABLED)) == 0) return true;
-    if (strncmp(key, NAME_GARLAND_BRIGHTNESS, strlen(NAME_GARLAND_BRIGHTNESS)) == 0) return true;
-    if (strncmp(key, NAME_GARLAND_SPEED, strlen(NAME_GARLAND_SPEED)) == 0) return true;
-    return false;
+bool _garlandWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, NAME_GARLAND_ENABLED)
+        || espurna::settings::query::samePrefix(key, NAME_GARLAND_BRIGHTNESS)
+        || espurna::settings::query::samePrefix(key, NAME_GARLAND_SPEED);
 }
 
 //------------------------------------------------------------------------------
diff --git a/code/espurna/homeassistant.cpp b/code/espurna/homeassistant.cpp
index f672bbef..e2c57d04 100644
--- a/code/espurna/homeassistant.cpp
+++ b/code/espurna/homeassistant.cpp
@@ -984,8 +984,8 @@ void onConnected(JsonObject& root) {
     root["haRetain"] = settings::retain();
 }
 
-bool onKeyCheck(const char* key, JsonVariant& value) {
-    return (strncmp(key, "ha", 2) == 0);
+bool onKeyCheck(espurna::StringView key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("ha"));
 }
 
 #endif
diff --git a/code/espurna/influxdb.cpp b/code/espurna/influxdb.cpp
index c07581b6..bc4881db 100644
--- a/code/espurna/influxdb.cpp
+++ b/code/espurna/influxdb.cpp
@@ -132,8 +132,8 @@ void _idbInitClient() {
 
 // -----------------------------------------------------------------------------
 
-bool _idbWebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    return (strncmp_P(key, PSTR("idb"), 3) == 0);
+bool _idbWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("idb"));
 }
 
 void _idbWebSocketOnVisible(JsonObject& root) {
diff --git a/code/espurna/ir.cpp b/code/espurna/ir.cpp
index 18b45f69..a09ee23a 100644
--- a/code/espurna/ir.cpp
+++ b/code/espurna/ir.cpp
@@ -1560,7 +1560,7 @@ void process(rx::DecodeResult& result) {
     key += F("irCmd");
     key += value;
 
-    auto cmd = espurna::settings::internal::get(key);
+    const auto cmd = espurna::settings::get(key);
     if (cmd) {
         internal::inject(cmd.ref());
     }
diff --git a/code/espurna/led.cpp b/code/espurna/led.cpp
index 46d01987..951a4e14 100644
--- a/code/espurna/led.cpp
+++ b/code/espurna/led.cpp
@@ -636,8 +636,7 @@ static constexpr espurna::settings::query::IndexedSetting IndexedSettings[] PROG
 };
 
 bool checkSamePrefix(StringView key) {
-    static constexpr char Prefix[] PROGMEM = "led";
-    return espurna::settings::query::samePrefix(key, Prefix);
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("led"));
 }
 
 String findValueFrom(StringView key) {
@@ -998,7 +997,7 @@ void callback(unsigned int type, const char* topic, char* payload) {
 namespace web {
 namespace {
 
-bool onKeyCheck(const char* key, JsonVariant&) {
+bool onKeyCheck(StringView key, const JsonVariant&) {
     return settings::query::checkSamePrefix(key);
 }
 
diff --git a/code/espurna/light.cpp b/code/espurna/light.cpp
index 6064013f..73237a82 100644
--- a/code/espurna/light.cpp
+++ b/code/espurna/light.cpp
@@ -2312,10 +2312,10 @@ void _lightApiSetup() {
 
 namespace {
 
-bool _lightWebSocketOnKeyCheck(const char* key, JsonVariant&) {
-    return (strncmp(key, "light", 5) == 0)
-        || (strncmp(key, "use", 3) == 0)
-        || (strncmp(key, "lt", 2) == 0);
+bool _lightWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("light"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("use"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("lt"));
 }
 
 void _lightWebSocketStatus(JsonObject& root) {
diff --git a/code/espurna/main.cpp b/code/espurna/main.cpp
index 71e5e253..6802e5a3 100644
--- a/code/espurna/main.cpp
+++ b/code/espurna/main.cpp
@@ -307,6 +307,21 @@ void setup() {
 } // namespace main
 
 } // namespace
+
+bool StringView::compare(StringView other) const {
+    if (other._len == _len) {
+        if (inFlash(_ptr)) {
+            return memcmp_P(other._ptr, _ptr, _len) == 0;
+        } else if (inFlash(other._ptr)) {
+            return memcmp_P(_ptr, other._ptr, _len) == 0;
+        }
+
+        return __builtin_memcmp(_ptr, other._ptr, _len);
+    }
+
+    return false;
+}
+
 } // namespace espurna
 
 void espurnaRegisterLoop(LoopCallback callback) {
diff --git a/code/espurna/migrate.cpp b/code/espurna/migrate.cpp
index e183a221..95fb8be8 100644
--- a/code/espurna/migrate.cpp
+++ b/code/espurna/migrate.cpp
@@ -36,7 +36,7 @@ namespace {
 void deletePrefixes(query::StringViewIterator prefixes) {
     std::vector<String> to_purge;
 
-    internal::foreach_prefix([&](StringView, String key, const kvs_type::ReadResult&) {
+    foreach_prefix([&](StringView, String key, const kvs_type::ReadResult&) {
         to_purge.push_back(std::move(key));
     }, prefixes);
 
diff --git a/code/espurna/mqtt.cpp b/code/espurna/mqtt.cpp
index aecb6222..537ae3ab 100644
--- a/code/espurna/mqtt.cpp
+++ b/code/espurna/mqtt.cpp
@@ -430,8 +430,7 @@ static constexpr espurna::settings::query::Setting Settings[] PROGMEM {
 };
 
 bool checkSamePrefix(espurna::StringView key) {
-    alignas(4) static constexpr char Prefix[] PROGMEM = "mqtt";
-    return espurna::settings::query::samePrefix(key, Prefix);
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("mqtt"));
 }
 
 String findValueFrom(espurna::StringView key) {
@@ -907,7 +906,7 @@ namespace {
 
 #if WEB_SUPPORT
 
-bool _mqttWebSocketOnKeyCheck(const char * key, JsonVariant&) {
+bool _mqttWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
     return mqtt::settings::query::checkSamePrefix(key);
 }
 
diff --git a/code/espurna/nofuss.cpp b/code/espurna/nofuss.cpp
index b4989c8d..45d72407 100644
--- a/code/espurna/nofuss.cpp
+++ b/code/espurna/nofuss.cpp
@@ -28,8 +28,8 @@ bool _nofussEnabled = false;
 
 #if WEB_SUPPORT
 
-bool _nofussWebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    return (strncmp_P(key, PSTR("nofuss"), 6) == 0);
+bool _nofussWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("nofuss"));
 }
 
 void _nofussWebSocketOnVisible(JsonObject& root) {
diff --git a/code/espurna/ntp.cpp b/code/espurna/ntp.cpp
index e663251d..ee06a312 100644
--- a/code/espurna/ntp.cpp
+++ b/code/espurna/ntp.cpp
@@ -386,8 +386,8 @@ time_t now() {
 #if WEB_SUPPORT
 namespace web {
 
-bool onKeyCheck(const char * key, JsonVariant&) {
-    return (strncmp_P(key, PSTR("ntp"), 3) == 0);
+bool onKeyCheck(StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("ntp"));
 }
 
 void onVisible(JsonObject& root) {
@@ -399,8 +399,8 @@ void onData(JsonObject& root) {
 }
 
 void onConnected(JsonObject& root) {
-    root["ntpServer"] = ::espurna::ntp::settings::server();
-    root["ntpTZ"] = ::espurna::ntp::settings::tz();
+    root["ntpServer"] = settings::server();
+    root["ntpTZ"] = settings::tz();
 }
 
 } // namespace web
@@ -704,7 +704,7 @@ void convertLegacyOffsets() {
     bool dst { true };
     int offset { 60 };
 
-    espurna::settings::internal::foreach(
+    espurna::settings::foreach(
         [&](espurna::settings::kvs_type::KeyValueResult&& kv) {
             using namespace espurna::settings::internal;
             const auto key = kv.key.read();
diff --git a/code/espurna/relay.cpp b/code/espurna/relay.cpp
index 395ed911..0c22180d 100644
--- a/code/espurna/relay.cpp
+++ b/code/espurna/relay.cpp
@@ -345,7 +345,7 @@ alignas(4) static constexpr char Mode[] PROGMEM = "relayPulse";
 namespace {
 
 Result time(size_t index) {
-    auto time = espurna::settings::internal::get(espurna::settings::Key{keys::Time, index}.value());
+    const auto time = espurna::settings::get(espurna::settings::Key{keys::Time, index}.value());
     if (!time) {
         return Result(std::chrono::duration_cast<Duration>(build::time(index)));
     }
@@ -2163,8 +2163,8 @@ void _relayConfigure() {
 
 namespace {
 
-bool _relayWebSocketOnKeyCheck(const char* key, JsonVariant&) {
-    return strncmp_P(key, PSTR("relay"), 5) == 0;
+bool _relayWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("relay"));
 }
 
 void _relayWebSocketUpdate(JsonObject& root) {
@@ -2933,7 +2933,7 @@ String findIndexedValueFrom(StringView key) {
 
 bool checkExact(StringView key) {
     for (const auto& setting : Settings) {
-        if (setting.key().compareFlash(key)) {
+        if (key == setting.key()) {
             return true;
         }
     }
diff --git a/code/espurna/rfbridge.cpp b/code/espurna/rfbridge.cpp
index 31b1a752..18ddcb72 100644
--- a/code/espurna/rfbridge.cpp
+++ b/code/espurna/rfbridge.cpp
@@ -457,8 +457,8 @@ void _rfbWebSocketOnAction(uint32_t client_id, const char* action, JsonObject& d
 #endif
 }
 
-bool _rfbWebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    return strncmp_P(key, PSTR("rfb"), 3) == 0;
+bool _rfbWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("rfb"));
 }
 
 #endif // WEB_SUPPORT
diff --git a/code/espurna/rfm69.cpp b/code/espurna/rfm69.cpp
index 6773c780..9db2c1be 100644
--- a/code/espurna/rfm69.cpp
+++ b/code/espurna/rfm69.cpp
@@ -241,8 +241,8 @@ void _rfm69WebSocketOnConnected(JsonObject& root) {
     }
 }
 
-bool _rfm69WebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    return (strncmp(key, "rfm69", 5) == 0);
+bool _rfm69WebSocketOnKeyCheck(espurna::StringView key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("rfm69"));
 }
 
 void _rfm69WebSocketOnAction(uint32_t client_id, const char* action, JsonObject& data) {
diff --git a/code/espurna/rpnrules.cpp b/code/espurna/rpnrules.cpp
index c993b132..b501c156 100644
--- a/code/espurna/rpnrules.cpp
+++ b/code/espurna/rpnrules.cpp
@@ -354,8 +354,8 @@ void setup() {
 #if WEB_SUPPORT
 namespace web {
 
-bool onKeyCheck(const char * key, JsonVariant& value) {
-    return strncmp_P(key, PSTR("rpn"), 3) == 0;
+bool onKeyCheck(espurna::StringView key, const JsonVariant& value) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("rpn"));
 }
 
 void onVisible(JsonObject& root) {
diff --git a/code/espurna/scheduler.cpp b/code/espurna/scheduler.cpp
index 422f9a2b..07ca8b0c 100644
--- a/code/espurna/scheduler.cpp
+++ b/code/espurna/scheduler.cpp
@@ -563,8 +563,8 @@ void setup() {
 #if WEB_SUPPORT
 namespace web {
 
-bool onKey(const char* key, JsonVariant&) {
-    return strncmp_P(key, PSTR("sch"), 3) == 0;
+bool onKey(StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("sch"));
 }
 
 void onVisible(JsonObject& root) {
diff --git a/code/espurna/sensor.cpp b/code/espurna/sensor.cpp
index 2a3b7382..d0166f93 100644
--- a/code/espurna/sensor.cpp
+++ b/code/espurna/sensor.cpp
@@ -3074,7 +3074,7 @@ void migrate(int version) {
 namespace web {
 namespace {
 
-bool onKeyCheck(const char* key, JsonVariant&) {
+bool onKeyCheck(StringView key, const JsonVariant&) {
     return settings::query::check(key);
 }
 
diff --git a/code/espurna/settings.cpp b/code/espurna/settings.cpp
index 66e01065..b8cd023b 100644
--- a/code/espurna/settings.cpp
+++ b/code/espurna/settings.cpp
@@ -131,8 +131,6 @@ bool EnumerationNumericHelper::check(const String& value) {
 
 } // namespace options
 
-namespace internal {
-
 ValueResult get(const String& key) {
     return kv_store.get(key);
 }
@@ -183,6 +181,8 @@ void foreach_prefix(PrefixResultCallback&& callback, query::StringViewIterator p
 
 // --------------------------------------------------------------------------
 
+namespace internal {
+
 template <>
 float convert(const String& value) {
     return atof(value.c_str());
@@ -261,13 +261,14 @@ unsigned char convert(const String& value) {
 } // namespace internal
 
 // TODO: UI needs this to avoid showing keys in storage order
-std::vector<String> keys() {
-    auto keys = internal::keys();
-    std::sort(keys.begin(), keys.end(), [](const String& rhs, const String& lhs) -> bool {
-        return lhs.compareTo(rhs) > 0;
-    });
+std::vector<String> sorted_keys() {
+    auto values = keys();
+    std::sort(values.begin(), values.end(),
+        [](const String& lhs, const String& rhs) -> bool {
+            return rhs.compareTo(lhs) > 0;
+        });
 
-    return keys;
+    return values;
 }
 
 #if TERMINAL_SUPPORT
@@ -300,18 +301,22 @@ void config(::terminal::CommandContext&& ctx) {
 }
 
 void keys(::terminal::CommandContext&& ctx) {
-    auto keys = settingsKeys();
+    const auto keys = settings::sorted_keys();
 
     String value;
-    for (unsigned int i=0; i<keys.size(); i++) {
-        value = getSetting(keys[i]);
-        ctx.output.printf_P(PSTR("> %s => \"%s\"\n"), (keys[i]).c_str(), value.c_str());
+    for (const auto& key : keys) {
+        value = getSetting(key);
+        ctx.output.printf_P(PSTR("> %s => \"%s\"\n"),
+            key.c_str(), value.c_str());
     }
 
-    auto available [[gnu::unused]] = internal::available();
-    ctx.output.printf_P(PSTR("Number of keys: %u\n"), keys.size());
-    ctx.output.printf_P(PSTR("Available: %u bytes (%u%%)\n"),
-            available, (100 * available) / internal::size());
+    const auto size = settings::size();
+    if (size > 0) {
+        const auto available = settings::available();
+        ctx.output.printf_P(PSTR("Number of keys: %u\n"), keys.size());
+        ctx.output.printf_P(PSTR("Available: %u bytes (%u%%)\n"),
+                available, (100 * available) / size);
+    }
 
     terminalOK(ctx);
 }
@@ -324,7 +329,7 @@ void del(::terminal::CommandContext&& ctx) {
 
     int result = 0;
     for (auto it = (ctx.argv.begin() + 1); it != ctx.argv.end(); ++it) {
-        result += settings::internal::del(*it);
+        result += settings::del(*it);
     }
 
     if (result) {
@@ -340,7 +345,7 @@ void set(::terminal::CommandContext&& ctx) {
         return;
     }
 
-    if (espurna::settings::internal::set(ctx.argv[1], ctx.argv[2])) {
+    if (settings::set(ctx.argv[1], ctx.argv[2])) {
         terminalOK(ctx);
         return;
     }
@@ -355,7 +360,7 @@ void get(::terminal::CommandContext&& ctx) {
     }
 
     for (auto it = (ctx.argv.cbegin() + 1); it != ctx.argv.cend(); ++it) {
-        auto result = internal::get(*it);
+        auto result = settings::get(*it);
         if (!result) {
             const auto maybeValue = query::find(*it);
             if (maybeValue.length()) {
@@ -383,6 +388,7 @@ void factory_reset(::terminal::CommandContext&& ctx) {
     terminalOK(ctx);
 }
 
+[[gnu::unused]]
 void save(::terminal::CommandContext&& ctx) {
     eepromCommit();
     terminalOK(ctx);
@@ -418,11 +424,11 @@ void setup() {
 // -----------------------------------------------------------------------------
 
 size_t settingsSize() {
-    return espurna::settings::internal::size() - espurna::settings::internal::available();
+    return espurna::settings::size() - espurna::settings::available();
 }
 
-std::vector<String> settingsKeys() {
-    return espurna::settings::keys();
+espurna::settings::Keys settingsKeys() {
+    return espurna::settings::sorted_keys();
 }
 
 void settingsRegisterQueryHandler(espurna::settings::query::Handler handler) {
@@ -434,36 +440,45 @@ String settingsQuery(espurna::StringView key) {
 }
 
 void moveSetting(const String& from, const String& to) {
-    auto result = espurna::settings::internal::get(from);
+    const auto result = espurna::settings::get(from);
     if (result) {
         setSetting(to, result.ref());
+        delSetting(from);
     }
-    delSetting(from);
 }
 
-using SettingsKeyPair = std::pair<espurna::settings::Key, espurna::settings::Key>;
+struct SettingsKeyPair {
+    espurna::settings::Key from;
+    espurna::settings::Key to;
+};
 
 void moveSetting(const String& from, const String& to, size_t index) {
-    const SettingsKeyPair keys = {{from, index}, {to, index}};
+    const auto keys = SettingsKeyPair{
+        .from = {from, index},
+        .to = {to, index}
+    };
 
-    auto result = espurna::settings::internal::get(keys.first.value());
+    const auto result = espurna::settings::get(keys.from.value());
     if (result) {
-        setSetting(keys.second, result.ref());
+        setSetting(keys.to, result.ref());
+        delSetting(keys.from);
     }
-
-    delSetting(keys.first);
 }
 
 void moveSettings(const String& from, const String& to) {
     for (size_t index = 0; index < 100; ++index) {
-        const SettingsKeyPair keys = {{from, index}, {to, index}};
-        auto result = espurna::settings::internal::get(keys.first.value());
+        const auto keys = SettingsKeyPair{
+            .from = {from, index},
+            .to = {to, index}
+        };
+
+        const auto result = espurna::settings::get(keys.from.value());
         if (!result) {
             break;
         }
 
-        setSetting(keys.second, result.ref());
-        delSetting(keys.first);
+        setSetting(keys.to, result.ref());
+        delSetting(keys.from);
     }
 }
 
@@ -495,7 +510,7 @@ template
 double getSetting(const espurna::settings::Key& key, double defaultValue);
 
 String getSetting(const String& key) {
-    return std::move(espurna::settings::internal::get(key)).get();
+    return std::move(espurna::settings::get(key)).get();
 }
 
 String getSetting(const __FlashStringHelper* key) {
@@ -520,7 +535,7 @@ String getSetting(const espurna::settings::Key& key, const __FlashStringHelper*
 }
 
 String getSetting(const espurna::settings::Key& key, const String& defaultValue) {
-    auto result = espurna::settings::internal::get(key.value());
+    auto result = espurna::settings::get(key.value());
     if (result) {
         return std::move(result).get();
     }
@@ -529,7 +544,7 @@ String getSetting(const espurna::settings::Key& key, const String& defaultValue)
 }
 
 String getSetting(const espurna::settings::Key& key, String&& defaultValue) {
-    auto result = espurna::settings::internal::get(key.value());
+    auto result = espurna::settings::get(key.value());
     if (result) {
         return std::move(result).get();
     }
@@ -538,7 +553,7 @@ String getSetting(const espurna::settings::Key& key, String&& defaultValue) {
 }
 
 bool delSetting(const String& key) {
-    return espurna::settings::internal::del(key);
+    return espurna::settings::del(key);
 }
 
 bool delSetting(const espurna::settings::Key& key) {
@@ -554,7 +569,7 @@ bool delSetting(const __FlashStringHelper* key) {
 }
 
 bool hasSetting(const String& key) {
-    return espurna::settings::internal::has(key);
+    return espurna::settings::has(key);
 }
 
 bool hasSetting(const espurna::settings::Key& key) {
@@ -636,16 +651,11 @@ bool settingsRestoreJson(char* json_string, size_t json_buffer_size) {
  }
 
 void settingsGetJson(JsonObject& root) {
-
-    // Get sorted list of keys
-    auto keys = settingsKeys();
-
-    // Add the key-values to the json object
-    for (unsigned int i=0; i<keys.size(); i++) {
-        String value = getSetting(keys[i]);
-        root[keys[i]] = value;
+    auto keys = espurna::settings::sorted_keys();
+    for (const auto& key : keys) {
+        auto value = getSetting(key);
+        root[key] = value;
     }
-
 }
 
 // -----------------------------------------------------------------------------
diff --git a/code/espurna/settings.h b/code/espurna/settings.h
index 4f69eea5..4d9e7bcd 100644
--- a/code/espurna/settings.h
+++ b/code/espurna/settings.h
@@ -50,17 +50,19 @@ public:
 
 using kvs_type = embedis::KeyValueStore<EepromStorage>;
 
-namespace internal {
+namespace traits {
 
-template <typename T>
+template<typename T>
 using is_arduino_string = std::is_same<String, typename std::decay<T>::type>;
 
-template <typename T>
+template<typename T>
 using enable_if_arduino_string = std::enable_if<is_arduino_string<T>::value>;
 
-template <typename T>
+template<typename T>
 using enable_if_not_arduino_string = std::enable_if<!is_arduino_string<T>::value>;
 
+} // namespace types
+
 ValueResult get(const String& key);
 bool set(const String& key, const String& value);
 bool del(const String& key);
@@ -80,6 +82,8 @@ void foreach_prefix(PrefixResultCallback&&, settings::query::StringViewIterator)
 
 // --------------------------------------------------------------------------
 
+namespace internal {
+
 template <typename T>
 T convert(const String& value);
 
@@ -228,22 +232,21 @@ String getSetting(const espurna::settings::Key& key, const String& defaultValue)
 String getSetting(const espurna::settings::Key& key, const String& defaultValue);
 String getSetting(const espurna::settings::Key& key, String&& defaultValue);
 
-template <typename T, typename = typename espurna::settings::internal::enable_if_not_arduino_string<T>::type>
+template <typename T, typename = typename espurna::settings::traits::enable_if_not_arduino_string<T>::type>
 T getSetting(const espurna::settings::Key& key, T defaultValue) {
-    using namespace espurna::settings::internal;
-    auto result = get(key.value());
+    auto result = espurna::settings::get(key.value());
     if (result) {
-        return convert<T>(result.ref());
+        return espurna::settings::internal::convert<T>(result.ref());
     }
     return defaultValue;
 }
 
-template<typename T, typename = typename espurna::settings::internal::enable_if_arduino_string<T>::type>
+template <typename T, typename = typename espurna::settings::traits::enable_if_arduino_string<T>::type>
 bool setSetting(const espurna::settings::Key& key, T&& value) {
-    return espurna::settings::internal::set(key.value(), value);
+    return espurna::settings::set(key.value(), value);
 }
 
-template<typename T, typename = typename espurna::settings::internal::enable_if_not_arduino_string<T>::type>
+template <typename T, typename = typename espurna::settings::traits::enable_if_not_arduino_string<T>::type>
 bool setSetting(const espurna::settings::Key& key, T value) {
     return setSetting(key, String(value));
 }
@@ -283,7 +286,7 @@ bool settingsRestoreJson(char* json_string, size_t json_buffer_size = 1024);
 bool settingsRestoreJson(JsonObject& data);
 
 size_t settingsKeyCount();
-std::vector<String> settingsKeys();
+espurna::settings::Keys settingsKeys();
 
 size_t settingsSize();
 
@@ -303,7 +306,7 @@ void migrate();
 // Deprecated implementation
 // -----------------------------------------------------------------------------
 
-template <typename T>
+template<typename T>
 String getSetting(const String& key, unsigned char index, T defaultValue)
 __attribute__((deprecated("getSetting({key, index}, default) should be used instead")));
 
diff --git a/code/espurna/settings_helpers.h b/code/espurna/settings_helpers.h
index cd0c6be4..da89e41c 100644
--- a/code/espurna/settings_helpers.h
+++ b/code/espurna/settings_helpers.h
@@ -365,8 +365,8 @@ struct alignas(8) Setting {
         return _key == key;
     }
 
-    bool operator==(const StringView& key) const {
-        return _key.compareFlash(key);
+    bool operator==(StringView key) const {
+        return _key == key;
     }
 
     static String findValueFrom(const Setting* begin, const Setting* end, StringView key);
diff --git a/code/espurna/system.cpp b/code/espurna/system.cpp
index 7e7add05..6544c1ec 100644
--- a/code/espurna/system.cpp
+++ b/code/espurna/system.cpp
@@ -775,10 +775,9 @@ void onConnected(JsonObject& root) {
       espurna::settings::internal::serialize(heartbeat::settings::mode());
 }
 
-bool onKeyCheck(const char* key, JsonVariant&) {
-    const auto view = StringView(key);
-    return espurna::settings::query::samePrefix(view, STRING_VIEW("sys"))
-        || espurna::settings::query::samePrefix(view, STRING_VIEW("hb"));
+bool onKeyCheck(StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("sys"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("hb"));
 }
 
 void init() {
diff --git a/code/espurna/telnet.cpp b/code/espurna/telnet.cpp
index d6e1a624..4bb6782f 100644
--- a/code/espurna/telnet.cpp
+++ b/code/espurna/telnet.cpp
@@ -97,8 +97,8 @@ bool _telnetClientsAuth[TELNET_MAX_CLIENTS];
 
 #if WEB_SUPPORT
 
-bool _telnetWebSocketOnKeyCheck(const char * key, JsonVariant&) {
-    return strncmp_P(key, PSTR("telnet"), 6) == 0;
+bool _telnetWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("telnet"));
 }
 
 void _telnetWebSocketOnVisible(JsonObject& root) {
diff --git a/code/espurna/thermostat.cpp b/code/espurna/thermostat.cpp
index 9b3ba8fd..d21d1709 100644
--- a/code/espurna/thermostat.cpp
+++ b/code/espurna/thermostat.cpp
@@ -813,18 +813,18 @@ void _thermostatWebSocketOnConnected(JsonObject& root) {
 }
 
 //------------------------------------------------------------------------------
-bool _thermostatWebSocketOnKeyCheck(const char * key, JsonVariant& value) {
-    if (strncmp(key, NAME_THERMOSTAT_ENABLED,   strlen(NAME_THERMOSTAT_ENABLED))   == 0) return true;
-    if (strncmp(key, NAME_THERMOSTAT_MODE,      strlen(NAME_THERMOSTAT_MODE))      == 0) return true;
-    if (strncmp(key, NAME_TEMP_RANGE_MIN,       strlen(NAME_TEMP_RANGE_MIN))       == 0) return true;
-    if (strncmp(key, NAME_TEMP_RANGE_MAX,       strlen(NAME_TEMP_RANGE_MAX))       == 0) return true;
-    if (strncmp(key, NAME_REMOTE_SENSOR_NAME,   strlen(NAME_REMOTE_SENSOR_NAME))   == 0) return true;
-    if (strncmp(key, NAME_REMOTE_TEMP_MAX_WAIT, strlen(NAME_REMOTE_TEMP_MAX_WAIT)) == 0) return true;
-    if (strncmp(key, NAME_MAX_ON_TIME,          strlen(NAME_MAX_ON_TIME))          == 0) return true;
-    if (strncmp(key, NAME_MIN_OFF_TIME,         strlen(NAME_MIN_OFF_TIME))         == 0) return true;
-    if (strncmp(key, NAME_ALONE_ON_TIME,        strlen(NAME_ALONE_ON_TIME))        == 0) return true;
-    if (strncmp(key, NAME_ALONE_OFF_TIME,       strlen(NAME_ALONE_OFF_TIME))       == 0) return true;
-    return false;
+bool _thermostatWebSocketOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return key == NAME_THERMOSTAT_ENABLED
+        || key == NAME_THERMOSTAT_ENABLED
+        || key == NAME_THERMOSTAT_MODE
+        || key == NAME_TEMP_RANGE_MIN
+        || key == NAME_TEMP_RANGE_MAX
+        || key == NAME_REMOTE_SENSOR_NAME
+        || key == NAME_REMOTE_TEMP_MAX_WAIT
+        || key == NAME_MAX_ON_TIME
+        || key == NAME_MIN_OFF_TIME
+        || key == NAME_ALONE_ON_TIME
+        || key == NAME_ALONE_OFF_TIME;
 }
 
 //------------------------------------------------------------------------------
diff --git a/code/espurna/thingspeak.cpp b/code/espurna/thingspeak.cpp
index 4cfc0d32..62c6b640 100644
--- a/code/espurna/thingspeak.cpp
+++ b/code/espurna/thingspeak.cpp
@@ -676,8 +676,8 @@ void loop() {
 namespace web {
 namespace {
 
-bool onKeyCheck(const char* key, JsonVariant& value) {
-    return (strncmp_P(key, PSTR("tspk"), 4) == 0);
+bool onKeyCheck(StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("tspk"));
 }
 
 void onVisible(JsonObject& root) {
diff --git a/code/espurna/types.h b/code/espurna/types.h
index 4e15bd23..f147ae71 100644
--- a/code/espurna/types.h
+++ b/code/espurna/types.h
@@ -8,6 +8,10 @@ Copyright (C) 2019-2021 by Maxim Prokhorov <prokhorov dot max at outlook dot com
 #pragma once
 
 #include <Arduino.h>
+#include <sys/pgmspace.h>
+
+// missing in our original header
+extern "C" int memcmp_P(const void*, const void*, size_t);
 
 namespace espurna {
 
@@ -88,16 +92,6 @@ struct StringView {
         return _len;
     }
 
-    bool compareRam(const StringView& other) const {
-        return (other._len == _len)
-            && (strncmp(other._ptr, _ptr, _len) == 0);
-    }
-
-    bool compareFlash(const StringView& other) const {
-        return (other._len == _len)
-            && (strncmp_P(other._ptr, _ptr, _len) == 0);
-    }
-
     String toString() const {
         String out;
         out.concat(_ptr, _len);
@@ -108,17 +102,23 @@ struct StringView {
         return toString();
     }
 
+    bool compare(StringView other) const;
+
 private:
+    static bool inFlash(const char* ptr) {
+        // common comparison would use >=0x40000000
+        // instead, slightly reduce the footprint by
+        // checking *only* for numbers below it
+        static constexpr uintptr_t Mask { 1 << 30 };
+        return (reinterpret_cast<uintptr_t>(ptr) & Mask) > 0;
+    }
+
     const char* _ptr;
     size_t _len;
 };
 
-inline bool operator==(const StringView& lhs, const char* rhs) {
-    return lhs.compareFlash(rhs);
-}
-
-inline bool operator==(const StringView& lhs, const String& rhs) {
-    return lhs.compareFlash(rhs);
+inline bool operator==(StringView lhs, StringView rhs) {
+    return lhs.compare(rhs);
 }
 
 inline String operator+(String&& lhs, StringView rhs) {
diff --git a/code/espurna/web.cpp b/code/espurna/web.cpp
index a94dd79c..798d4e5e 100644
--- a/code/espurna/web.cpp
+++ b/code/espurna/web.cpp
@@ -339,7 +339,7 @@ void _onGetConfig(AsyncWebServerRequest *request) {
     }
     out->concat(buffer, prefix_len);
 
-    espurna::settings::internal::foreach([&](espurna::settings::kvs_type::KeyValueResult&& kv) {
+    espurna::settings::foreach([&](espurna::settings::kvs_type::KeyValueResult&& kv) {
         auto key = kv.key.read();
         auto value = kv.value.read();
 
diff --git a/code/espurna/wifi.cpp b/code/espurna/wifi.cpp
index 03b24a38..1da49356 100644
--- a/code/espurna/wifi.cpp
+++ b/code/espurna/wifi.cpp
@@ -2388,10 +2388,9 @@ void onConnected(JsonObject& root) {
     container[F("max")] = wifi::sta::build::NetworksMax;
 }
 
-bool onKeyCheck(const char* key, JsonVariant&) {
-    const auto key_view = StringView(key);
-    return wifi::settings::query::checkExactPrefix(key_view)
-        || wifi::settings::query::checkIndexedPrefix(key_view);
+bool onKeyCheck(StringView key, const JsonVariant&) {
+    return wifi::settings::query::checkExactPrefix(key)
+        || wifi::settings::query::checkIndexedPrefix(key);
 }
 
 void onScan(uint32_t client_id) {
diff --git a/code/espurna/ws.cpp b/code/espurna/ws.cpp
index 6670b7f0..3f820e8e 100644
--- a/code/espurna/ws.cpp
+++ b/code/espurna/ws.cpp
@@ -427,10 +427,10 @@ namespace {
 
 // Check the existing setting before saving it
 // (we only care about the settings storage, don't mind the build values)
-bool _wsStore(const String& key, const String& value) {
-    auto current = espurna::settings::internal::get(key);
+bool _wsStore(String key, const String& value) {
+    const auto current = espurna::settings::get(key);
     if (!current || (current.ref() != value)) {
-        return espurna::settings::internal::set(key, value);
+        return espurna::settings::set(key, value);
     }
 
     return false;
@@ -438,15 +438,15 @@ bool _wsStore(const String& key, const String& value) {
 
 // TODO: generate "accepted" keys in the initial phase of the connection?
 // TODO: is value ever used... by anything?
-bool _wsCheckKey(const char* key, JsonVariant& value) {
+bool _wsCheckKey(const String& key, const JsonVariant& value) {
 #if NTP_SUPPORT
-    if (strncmp_P(key, PSTR("ntpTZ"), strlen(key)) == 0) {
+    if (key == STRING_VIEW("ntpTZ")) {
         _wsResetUpdateTimer();
         return true;
     }
 #endif
 
-    if (strncmp_P(key, PSTR("adminPass"), strlen(key)) == 0) {
+    if (key == STRING_VIEW("adminPass")) {
         const auto pass = getAdminPass();
         return !pass.equalsConstantTime(value.as<String>());
     }
@@ -579,27 +579,23 @@ void _wsParse(AsyncWebSocketClient *client, uint8_t * payload, size_t length) {
     // TODO: pass key as string, we always attempt to use it as such
     JsonObject& toAssign = settings["set"];
     for (auto& kv : toAssign) {
-        String key = kv.key;
-        JsonVariant& value = kv.value;
-        if (!_wsCheckKey(key.c_str(), value)) {
-            continue;
-        }
-
-        if (_wsStore(key, value.as<String>())) {
-            save = true;
+        const String key = kv.key;
+        if (_wsCheckKey(key, kv.value)) {
+            if (_wsStore(key, kv.value.as<String>())) {
+                save = true;
+            }
         }
     }
 
     _wsPostParse(client_id, save, reload);
 }
 
-bool _wsOnKeyCheck(const char* key, JsonVariant&) {
-    const auto keylen = strlen(key);
-    return (strncmp_P(key, PSTR("ws"), 2) == 0)
-        || (strncmp_P(key, PSTR("adminPass"), keylen) == 0)
-        || (strncmp_P(key, PSTR("hostname"), keylen) == 0)
-        || (strncmp_P(key, PSTR("desc"), keylen) == 0)
-        || (strncmp_P(key, PSTR("webPort"), keylen) == 0);
+bool _wsOnKeyCheck(espurna::StringView key, const JsonVariant&) {
+    return espurna::settings::query::samePrefix(key, STRING_VIEW("ws"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("adminPass"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("hostname"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("desc"))
+        || espurna::settings::query::samePrefix(key, STRING_VIEW("webPort"));
 }
 
 void _wsOnConnected(JsonObject& root) {
diff --git a/code/espurna/ws.h b/code/espurna/ws.h
index caeb63f1..aa865c52 100644
--- a/code/espurna/ws.h
+++ b/code/espurna/ws.h
@@ -32,8 +32,8 @@ Copyright (C) 2019 by Maxim Prokhorov <prokhorov dot max at outlook dot com>
 // - on_keycheck will be used to determine if we can handle specific settings keys
 
 using ws_on_send_callback_f = std::function<void(JsonObject& root)>;
-using ws_on_action_callback_f = std::function<void(uint32_t client_id, const char * action, JsonObject& data)>;
-using ws_on_keycheck_callback_f = std::function<bool(const char * key, JsonVariant& value)>;
+using ws_on_action_callback_f = std::function<void(uint32_t client_id, const char* action, JsonObject& data)>;
+using ws_on_keycheck_callback_f = std::function<bool(espurna::StringView key, const JsonVariant& value)>;
 
 // TODO: use iterators as inputs for Post(), avoid depending on vector / any specific container
 using ws_on_send_callback_list_t = std::vector<ws_on_send_callback_f>;
@@ -49,7 +49,7 @@ struct ws_callbacks_t {
     using on_action_f = void(*)(uint32_t, const char*, JsonObject&);
     ws_callbacks_t& onAction(on_action_f);
 
-    using on_keycheck_f = bool(*)(const char*, JsonVariant&);
+    using on_keycheck_f = bool(*)(espurna::StringView, const JsonVariant&);
     ws_callbacks_t& onKeyCheck(on_keycheck_f);
 
     ws_on_send_callback_list_t on_visible;