diff --git a/usermods/Analog_Clock/Analog_Clock.cpp b/usermods/Analog_Clock/Analog_Clock.cpp
index d3a2b73b8d..3e0a1e99a6 100644
--- a/usermods/Analog_Clock/Analog_Clock.cpp
+++ b/usermods/Analog_Clock/Analog_Clock.cpp
@@ -3,7 +3,6 @@
 /*
  * Usermod for analog clock
  */
-extern Timezone* tz;
 
 class AnalogClockUsermod : public Usermod {
 private:
diff --git a/wled00/FX.cpp b/wled00/FX.cpp
index ddffeb039a..54f441da35 100644
--- a/wled00/FX.cpp
+++ b/wled00/FX.cpp
@@ -82,12 +82,12 @@
 //#define MAX_FREQ_LOG10  3.71f
 
 // effect utility functions
-uint8_t sin_gap(uint16_t in) {
+static uint8_t sin_gap(uint16_t in) {
   if (in & 0x100) return 0;
   return sin8_t(in + 192); // correct phase shift of sine so that it starts and stops at 0
 }
 
-uint16_t triwave16(uint16_t in) {
+static uint16_t triwave16(uint16_t in) {
   if (in < 0x8000) return in *2;
   return 0xFFFF - (in - 0x8000)*2;
 }
@@ -99,7 +99,7 @@ uint16_t triwave16(uint16_t in) {
  * @param attdec attack & decay, max. pulsewidth / 2
  * @returns signed waveform value
  */
-int8_t tristate_square8(uint8_t x, uint8_t pulsewidth, uint8_t attdec) {
+static int8_t tristate_square8(uint8_t x, uint8_t pulsewidth, uint8_t attdec) {
   int8_t a = 127;
   if (x > 127) {
     a = -127;
diff --git a/wled00/bus_manager.cpp b/wled00/bus_manager.cpp
index 017f1dd1f3..2ae0f5d4a0 100644
--- a/wled00/bus_manager.cpp
+++ b/wled00/bus_manager.cpp
@@ -17,21 +17,17 @@
 #include "bus_wrapper.h"
 #include "wled.h"
 
-extern char cmDNS[];
-extern bool cctICused;
-extern bool useParallelI2S;
-
 // functions to get/set bits in an array - based on functions created by Brandon for GOL
 //  toDo : make this a class that's completely defined in a header file
 // note: these functions are automatically inline by the compiler
-bool getBitFromArray(const uint8_t* byteArray, size_t position) { // get bit value
+static inline bool getBitFromArray(const uint8_t* byteArray, size_t position) { // get bit value
   size_t byteIndex = position >> 3;    // divide by 8
   unsigned bitIndex = position & 0x07; // modulo 8
   uint8_t byteValue = byteArray[byteIndex];
   return (byteValue >> bitIndex) & 1;
 }
 
-void setBitInArray(uint8_t* byteArray, size_t position, bool value) {  // set bit - with error handling for nullptr
+static inline void setBitInArray(uint8_t* byteArray, size_t position, bool value) {  // set bit - with error handling for nullptr
     //if (byteArray == nullptr) return;
     size_t byteIndex = position >> 3;    // divide by 8
     unsigned bitIndex = position & 0x07; // modulo 8
@@ -41,11 +37,11 @@ void setBitInArray(uint8_t* byteArray, size_t position, bool value) {  // set bi
         byteArray[byteIndex] &= ~(1 << bitIndex);
 }
 
-size_t getBitArrayBytes(size_t num_bits) { // number of bytes needed for an array with num_bits bits
+static inline size_t getBitArrayBytes(size_t num_bits) { // number of bytes needed for an array with num_bits bits
   return (num_bits + 7) >> 3;
 }
 
-void setBitArray(uint8_t* byteArray, size_t numBits, bool value) {  // set all bits to same value
+static inline void setBitArray(uint8_t* byteArray, size_t numBits, bool value) {  // set all bits to same value
   if (byteArray == nullptr) return;
   size_t len =  getBitArrayBytes(numBits);
   if (value) memset(byteArray, 0xFF, len);
diff --git a/wled00/cfg.cpp b/wled00/cfg.cpp
index 6e26b22200..37028130fe 100644
--- a/wled00/cfg.cpp
+++ b/wled00/cfg.cpp
@@ -38,7 +38,7 @@ static constexpr bool validatePinsAndTypes(const unsigned* types, unsigned numTy
 //simple macro for ArduinoJSON's or syntax
 #define CJSON(a,b) a = b | a
 
-void getStringFromJson(char* dest, const char* src, size_t len) {
+static inline void getStringFromJson(char* dest, const char* src, size_t len) {
   if (src != nullptr) strlcpy(dest, src, len);
 }
 
diff --git a/wled00/e131.cpp b/wled00/e131.cpp
index 357e7841fe..8029feec3e 100644
--- a/wled00/e131.cpp
+++ b/wled00/e131.cpp
@@ -4,13 +4,20 @@
 #define MAX_4_CH_LEDS_PER_UNIVERSE 128
 #define MAX_CHANNELS_PER_UNIVERSE 512
 
+// forward declarations
+static void handleDDPPacket(e131_packet_t* p);
+static void handleArtnetPollReply(IPAddress ipAddress);
+static void prepareArtnetPollReply(ArtPollReply *reply);
+static void sendArtnetPollReply(ArtPollReply *reply, IPAddress ipAddress, uint16_t portAddress);
+
+
 /*
  * E1.31 handler
  */
 
 //DDP protocol support, called by handleE131Packet
 //handles RGB data only
-void handleDDPPacket(e131_packet_t* p) {
+static void handleDDPPacket(e131_packet_t* p) {
   static bool ddpSeenPush = false;  // have we seen a push yet?
   int lastPushSeq = e131LastSequenceNumber[0];
 
@@ -336,7 +343,7 @@ void handleDMXData(uint16_t uni, uint16_t dmxChannels, uint8_t* e131_data, uint8
   e131NewData = true;
 }
 
-void handleArtnetPollReply(IPAddress ipAddress) {
+static void handleArtnetPollReply(IPAddress ipAddress) {
   ArtPollReply artnetPollReply;
   prepareArtnetPollReply(&artnetPollReply);
 
@@ -402,7 +409,7 @@ void handleArtnetPollReply(IPAddress ipAddress) {
   #endif
 }
 
-void prepareArtnetPollReply(ArtPollReply *reply) {
+static void prepareArtnetPollReply(ArtPollReply *reply) {
   // Art-Net
   reply->reply_id[0] = 0x41;
   reply->reply_id[1] = 0x72;
@@ -521,7 +528,7 @@ void prepareArtnetPollReply(ArtPollReply *reply) {
   }
 }
 
-void sendArtnetPollReply(ArtPollReply *reply, IPAddress ipAddress, uint16_t portAddress) {
+static void sendArtnetPollReply(ArtPollReply *reply, IPAddress ipAddress, uint16_t portAddress) {
   reply->reply_net_sw = (uint8_t)((portAddress >> 8) & 0x007F);
   reply->reply_sub_sw = (uint8_t)((portAddress >> 4) & 0x000F);
   reply->reply_sw_out[0] = (uint8_t)(portAddress & 0x000F);
diff --git a/wled00/fcn_declare.h b/wled00/fcn_declare.h
index 8430e45cf4..84b6da9e61 100644
--- a/wled00/fcn_declare.h
+++ b/wled00/fcn_declare.h
@@ -99,9 +99,9 @@ void handleDMXInput();
 //e131.cpp
 void handleE131Packet(e131_packet_t* p, IPAddress clientIP, byte protocol);
 void handleDMXData(uint16_t uni, uint16_t dmxChannels, uint8_t* e131_data, uint8_t mde, uint8_t previousUniverses);
-void handleArtnetPollReply(IPAddress ipAddress);
-void prepareArtnetPollReply(ArtPollReply* reply);
-void sendArtnetPollReply(ArtPollReply* reply, IPAddress ipAddress, uint16_t portAddress);
+// void handleArtnetPollReply(IPAddress ipAddress);                                          // local function, only used in e131.cpp
+// void prepareArtnetPollReply(ArtPollReply* reply);                                         // local function, only used in e131.cpp
+// void sendArtnetPollReply(ArtPollReply* reply, IPAddress ipAddress, uint16_t portAddress); // local function, only used in e131.cpp
 
 //file.cpp
 bool handleFileRead(AsyncWebServerRequest*, String path);
@@ -207,8 +207,8 @@ void publishMqtt();
 //ntp.cpp
 void handleTime();
 void handleNetworkTime();
-void sendNTPPacket();
-bool checkNTPResponse();
+// void sendNTPPacket();    // local function, only used in ntp.cpp
+// bool checkNTPResponse(); // local function, only used in ntp.cpp
 void updateLocalTime();
 void getTimeString(char* out);
 bool checkCountdown();
@@ -221,8 +221,8 @@ void setTimeFromAPI(uint32_t timein);
 
 //overlay.cpp
 void handleOverlayDraw();
-void _overlayAnalogCountdown();
-void _overlayAnalogClock();
+// void _overlayAnalogCountdown();  // local function, only used in overlay.cpp
+// void _overlayAnalogClock();      // local function, only used in overlay.cpp
 
 //playlist.cpp
 void shufflePlaylist();
diff --git a/wled00/improv.cpp b/wled00/improv.cpp
index 0bc7a6698f..2d2d876d6e 100644
--- a/wled00/improv.cpp
+++ b/wled00/improv.cpp
@@ -16,8 +16,8 @@
 #endif
 
 #define IMPROV_VERSION 1
-
-void parseWiFiCommand(char *rpcData);
+// forward declarations
+static void parseWiFiCommand(char* rpcData);
 
 enum ImprovPacketType {
   Current_State = 0x01,
@@ -252,7 +252,7 @@ void startImprovWifiScan() {}
 void handleImprovWifiScan() {}
 #endif
 
-void parseWiFiCommand(char* rpcData) {
+static void parseWiFiCommand(char* rpcData) {
   unsigned len = rpcData[0];
   if (!len || len > 126) return;
 
diff --git a/wled00/ir.cpp b/wled00/ir.cpp
index fe0950ab14..6c9ea3ad5b 100644
--- a/wled00/ir.cpp
+++ b/wled00/ir.cpp
@@ -7,14 +7,14 @@
  * Infrared sensor support for several generic RGB remotes and custom JSON remote
  */
 
-IRrecv* irrecv;
-decode_results results;
-unsigned long irCheckedTime = 0;
-uint32_t lastValidCode = 0;
-byte lastRepeatableAction = ACTION_NONE;
-uint8_t lastRepeatableValue = 0;
-uint16_t irTimesRepeated = 0;
-uint8_t lastIR6ColourIdx = 0;
+static IRrecv* irrecv;
+static decode_results results;
+static unsigned long irCheckedTime = 0;
+static uint32_t lastValidCode = 0;
+static byte lastRepeatableAction = ACTION_NONE;
+static uint8_t lastRepeatableValue = 0;
+static uint16_t irTimesRepeated = 0;
+static uint8_t lastIR6ColourIdx = 0;
 
 
 // brightnessSteps: a static array of brightness levels following a geometric
diff --git a/wled00/json.cpp b/wled00/json.cpp
index 3e053708c0..15b7f75922 100644
--- a/wled00/json.cpp
+++ b/wled00/json.cpp
@@ -898,7 +898,7 @@ void serializeInfo(JsonObject root)
   root["ip"] = s;
 }
 
-void setPaletteColors(JsonArray json, CRGBPalette16 palette)
+static void setPaletteColors(JsonArray json, CRGBPalette16 palette)
 {
     for (int i = 0; i < 16; i++) {
       JsonArray colors =  json.createNestedArray();
@@ -910,7 +910,7 @@ void setPaletteColors(JsonArray json, CRGBPalette16 palette)
     }
 }
 
-void setPaletteColors(JsonArray json, byte* tcp)
+static void setPaletteColors(JsonArray json, byte* tcp)
 {
     TRGBGradientPaletteEntryUnion* ent = (TRGBGradientPaletteEntryUnion*)(tcp);
     TRGBGradientPaletteEntryUnion u;
diff --git a/wled00/ntp.cpp b/wled00/ntp.cpp
index abad5c3c9d..8244961d75 100644
--- a/wled00/ntp.cpp
+++ b/wled00/ntp.cpp
@@ -2,6 +2,11 @@
 #include "wled.h"
 #include "fcn_declare.h"
 
+// forward declarations
+static void sendNTPPacket();
+static bool checkNTPResponse();
+
+
 // WARNING: may cause errors in sunset calculations on ESP8266, see #3400
 // building with `-D WLED_USE_REAL_MATH` will prevent those errors at the expense of flash and RAM
 
@@ -11,7 +16,7 @@
 //#define WLED_DEBUG_NTP
 #define NTP_SYNC_INTERVAL 42000UL //Get fresh NTP time about twice per day
 
-Timezone* tz;
+static Timezone* tz;
 
 #define TZ_UTC                  0
 #define TZ_UK                   1
@@ -42,7 +47,7 @@ Timezone* tz;
 #define TZ_COUNT               25
 #define TZ_INIT               255
 
-byte tzCurrent = TZ_INIT; //uninitialized
+static byte tzCurrent = TZ_INIT; //uninitialized
 
 /* C++11 form -- static std::array<std::pair<TimeChangeRule, TimeChangeRule>, TZ_COUNT> TZ_TABLE PROGMEM = {{ */
 static const std::pair<TimeChangeRule, TimeChangeRule> TZ_TABLE[] PROGMEM = {
@@ -199,7 +204,7 @@ void handleNetworkTime()
   }
 }
 
-void sendNTPPacket()
+static void sendNTPPacket()
 {
   if (!ntpServerIP.fromString(ntpServerName)) //see if server is IP or domain
   {
@@ -245,7 +250,7 @@ static bool isValidNtpResponse(const byte* ntpPacket) {
   return true;
 }
 
-bool checkNTPResponse()
+static bool checkNTPResponse()
 {
   int cb = ntpUdp.parsePacket();
   if (cb < NTP_MIN_PACKET_SIZE) {
diff --git a/wled00/overlay.cpp b/wled00/overlay.cpp
index 3f6e631214..f5366f3b71 100644
--- a/wled00/overlay.cpp
+++ b/wled00/overlay.cpp
@@ -1,10 +1,13 @@
 #include "wled.h"
 
+// forward declarations
+static void _overlayAnalogCountdown();
+
 /*
  * Used to draw clock overlays over the strip
  */
 
-void _overlayAnalogClock()
+static void _overlayAnalogClock()
 {
   int overlaySize = overlayMax - overlayMin +1;
   if (countdownMode)
@@ -47,7 +50,7 @@ void _overlayAnalogClock()
 }
 
 
-void _overlayAnalogCountdown()
+static void _overlayAnalogCountdown()
 {
   if ((unsigned long)toki.second() < countdownTime)
   {
diff --git a/wled00/remote.cpp b/wled00/remote.cpp
index b5aaa5211c..9685e52fe4 100644
--- a/wled00/remote.cpp
+++ b/wled00/remote.cpp
@@ -109,7 +109,7 @@ static void setOff() {
   }
 }
 
-void presetWithFallback(uint8_t presetID, uint8_t effectID, uint8_t paletteID) {
+static void presetWithFallback(uint8_t presetID, uint8_t effectID, uint8_t paletteID) {
   resetNightMode();
   applyPresetWithFallback(presetID, CALL_MODE_BUTTON_PRESET, effectID, paletteID);
 }
diff --git a/wled00/set.cpp b/wled00/set.cpp
index ab3060d06d..d69bda905e 100644
--- a/wled00/set.cpp
+++ b/wled00/set.cpp
@@ -570,16 +570,16 @@ void handleSettingsSet(AsyncWebServerRequest *request, byte subPage)
     macroAlexaOff = request->arg(F("A1")).toInt();
     macroCountdown = request->arg(F("MC")).toInt();
     macroNl = request->arg(F("MN")).toInt();
-    int i = 0;
+    int ii = 0;
     for (auto &button : buttons) {
-      char mp[4] = "MP"; mp[2] = (i<10?'0':'A'-10)+i; mp[3] = 0; // short
-      char ml[4] = "ML"; ml[2] = (i<10?'0':'A'-10)+i; ml[3] = 0; // long
-      char md[4] = "MD"; md[2] = (i<10?'0':'A'-10)+i; md[3] = 0; // double
+      char mp[4] = "MP"; mp[2] = (ii<10?'0':'A'-10)+ii; mp[3] = 0; // short
+      char ml[4] = "ML"; ml[2] = (ii<10?'0':'A'-10)+ii; ml[3] = 0; // long
+      char md[4] = "MD"; md[2] = (ii<10?'0':'A'-10)+ii; md[3] = 0; // double
       //if (!request->hasArg(mp)) break;
       button.macroButton = request->arg(mp).toInt();      // these will default to 0 if not present
       button.macroLongPress = request->arg(ml).toInt();
       button.macroDoublePress = request->arg(md).toInt();
-      i++;
+      ii++;
     }
 
     char k[3]; k[2] = 0;
diff --git a/wled00/udp.cpp b/wled00/udp.cpp
index f0e0ea7ea0..fab67bc600 100644
--- a/wled00/udp.cpp
+++ b/wled00/udp.cpp
@@ -457,7 +457,7 @@ void exitRealtime() {
 
 #define TMP2NET_OUT_PORT 65442
 
-void sendTPM2Ack() {
+static void sendTPM2Ack() {
   notifierUdp.beginPacket(notifierUdp.remoteIP(), TMP2NET_OUT_PORT);
   uint8_t response_ack = 0xac;
   notifierUdp.write(&response_ack, 1);
diff --git a/wled00/util.cpp b/wled00/util.cpp
index bccb2d6920..f3c1b31825 100644
--- a/wled00/util.cpp
+++ b/wled00/util.cpp
@@ -370,7 +370,7 @@ int16_t extractModeDefaults(uint8_t mode, const char *segVar)
 void checkSettingsPIN(const char* pin) {
   if (!pin) return;
   if (!correctPIN && millis() - lastEditTime < PIN_RETRY_COOLDOWN) return; // guard against PIN brute force
-  bool correctBefore = correctPIN;
+  //bool correctBefore = correctPIN; // unused
   correctPIN = (strlen(settingsPIN) == 0 || strncmp(settingsPIN, pin, 4) == 0);
   lastEditTime = millis();
 }
diff --git a/wled00/wled_serial.cpp b/wled00/wled_serial.cpp
index 7675976ba8..dd04788df3 100644
--- a/wled00/wled_serial.cpp
+++ b/wled00/wled_serial.cpp
@@ -1,5 +1,8 @@
 #include "wled.h"
 
+// forward declarations
+static void sendBytes();
+
 /*
  * Adalight and TPM2 handler
  */
@@ -19,9 +22,9 @@ enum class AdaState {
   TPM2_Header_CountLo,
 };
 
-uint16_t currentBaud = 1152; //default baudrate 115200 (divided by 100)
-bool continuousSendLED = false;
-uint32_t lastUpdate = 0;
+static uint16_t currentBaud = 1152; //default baudrate 115200 (divided by 100)
+static bool continuousSendLED = false;
+static uint32_t lastUpdate = 0;
 
 void updateBaudRate(uint32_t rate){
   unsigned rate100 = rate/100;
@@ -37,7 +40,7 @@ void updateBaudRate(uint32_t rate){
 }
 
 // RGB LED data return as JSON array. Slow, but easy to use on the other end.
-void sendJSON(){
+static inline void sendJSON(){
   if (serialCanTX) {
     unsigned used = strip.getLengthTotal();
     Serial.write('[');
@@ -50,7 +53,7 @@ void sendJSON(){
 }
 
 // RGB LED data returned as bytes in TPM2 format. Faster, and slightly less easy to use on the other end.
-void sendBytes(){
+static void sendBytes(){
   if (serialCanTX) {
     Serial.write(0xC9); Serial.write(0xDA);
     unsigned used = strip.getLengthTotal();
diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index 687d734855..bcf7487fcf 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -19,6 +19,9 @@
 #include "html_cpal.h"
 #include "html_edit.h"
 
+// forward declarations
+static void createEditHandler();
+
 
 // define flash strings once (saves flash memory)
 static const char s_redirecting[] PROGMEM = "Redirecting...";
@@ -222,7 +225,7 @@ static void handleUpload(AsyncWebServerRequest *request, const String& filename,
 
 static const char _edit_htm[] PROGMEM = "/edit.htm";
 
-void createEditHandler() {
+static void createEditHandler() {
   if (editHandler != nullptr) server.removeHandler(editHandler);
 
   editHandler = &server.on(F("/edit"), static_cast<WebRequestMethod>(HTTP_GET), [](AsyncWebServerRequest *request) {
diff --git a/wled00/ws.cpp b/wled00/ws.cpp
index 6d74a5a0b8..5c4edcd352 100644
--- a/wled00/ws.cpp
+++ b/wled00/ws.cpp
@@ -5,15 +5,18 @@
  */
 #ifdef WLED_ENABLE_WEBSOCKETS
 
+// forward declarations
+static bool sendLiveLedsWs(uint32_t wsClient);
+
 // define some constants for binary protocols, dont use defines but C++ style constexpr
 constexpr uint8_t BINARY_PROTOCOL_GENERIC = 0xFF; // generic / auto detect NOT IMPLEMENTED
 constexpr uint8_t BINARY_PROTOCOL_E131    = P_E131; // = 0, untested!
 constexpr uint8_t BINARY_PROTOCOL_ARTNET  = P_ARTNET; // = 1, untested!
 constexpr uint8_t BINARY_PROTOCOL_DDP     = P_DDP; // = 2
 
-uint16_t wsLiveClientId = 0;
-unsigned long wsLastLiveTime = 0;
-//uint8_t* wsFrameBuffer = nullptr;
+static uint16_t wsLiveClientId = 0;
+static unsigned long wsLastLiveTime = 0;
+//static uint8_t* wsFrameBuffer = nullptr;
 
 #define WS_LIVE_INTERVAL 40
 
@@ -185,7 +188,7 @@ void sendDataWs(AsyncWebSocketClient * client)
   releaseJSONBufferLock();
 }
 
-bool sendLiveLedsWs(uint32_t wsClient)
+static bool sendLiveLedsWs(uint32_t wsClient)
 {
   AsyncWebSocketClient * wsc = ws.client(wsClient);
   if (!wsc || wsc->queueLength() > 0) return false; //only send if queue free
diff --git a/wled00/xml.cpp b/wled00/xml.cpp
index 0b6eafa4ec..ce5dec73d8 100644
--- a/wled00/xml.cpp
+++ b/wled00/xml.cpp
@@ -5,6 +5,9 @@
  * Sending XML status files to client
  */
 
+// forward declarations
+static void appendGPIOinfo(Print& settingsScript);
+
 //build XML response to HTTP /win API request
 void XML_response(Print& dest)
 {
@@ -38,7 +41,7 @@ static void extractPin(Print& settingsScript, const JsonObject &obj, const char
   }
 }
 
-void fillWLEDVersion(char *buf, size_t len)
+static void fillWLEDVersion(char *buf, size_t len)
 {
   if (!buf || len == 0) return;
 
@@ -89,7 +92,7 @@ static void fillUMPins(Print& settingsScript, const JsonObject &mods)
   }
 }
 
-void appendGPIOinfo(Print& settingsScript)
+static void appendGPIOinfo(Print& settingsScript)
 {
   settingsScript.print(F("d.um_p=[-1")); // has to have 1 element
   if (i2c_sda > -1 && i2c_scl > -1) {
@@ -593,9 +596,9 @@ void getSettingsJS(byte subPage, Print& settingsScript)
     printSetFormValue(settingsScript,PSTR("A1"),macroAlexaOff);
     printSetFormValue(settingsScript,PSTR("MC"),macroCountdown);
     printSetFormValue(settingsScript,PSTR("MN"),macroNl);
-    int i = 0;
+    int ii = 0;
     for (const auto &button : buttons) {
-      settingsScript.printf_P(PSTR("addRow(%d,%d,%d,%d);"), i++, button.macroButton, button.macroLongPress, button.macroDoublePress);
+      settingsScript.printf_P(PSTR("addRow(%d,%d,%d,%d);"), ii++, button.macroButton, button.macroLongPress, button.macroDoublePress);
     }
 
     char k[4];