diff --git a/src/lib/base/EventQueue.cpp b/src/lib/base/EventQueue.cpp
index 71c512f2c..be86841f8 100644
--- a/src/lib/base/EventQueue.cpp
+++ b/src/lib/base/EventQueue.cpp
@@ -298,16 +298,16 @@ void EventQueue::removeHandlers(void *target)
     if (index != m_handlers.end()) {
       // copy to handlers array and clear table for target
       TypeHandlerTable &typeHandlers = index->second;
-      for (auto index2 = typeHandlers.begin(); index2 != typeHandlers.end(); ++index2) {
-        handlers.push_back(index2->second);
+      for (const auto &[key, value] : typeHandlers) {
+        handlers.push_back(value);
       }
       typeHandlers.clear();
     }
   }
 
   // delete handlers
-  for (auto index = handlers.begin(); index != handlers.end(); ++index) {
-    delete *index;
+  for (auto index : handlers) {
+    delete index;
   }
 }
 
diff --git a/src/lib/deskflow/IKeyState.cpp b/src/lib/deskflow/IKeyState.cpp
index 2027d0a4f..c49a7f304 100644
--- a/src/lib/deskflow/IKeyState.cpp
+++ b/src/lib/deskflow/IKeyState.cpp
@@ -105,15 +105,15 @@ std::string IKeyState::KeyInfo::join(const std::set<std::string> &destinations)
   // which makes searching easy.  the string is empty if there are no
   // destinations and "*" means all destinations.
   std::string screens;
-  for (auto i = destinations.begin(); i != destinations.end(); ++i) {
-    if (*i == "*") {
+  for (const auto &i : destinations) {
+    if (i == "*") {
       screens = "*";
       break;
     } else {
       if (screens.empty()) {
         screens = ":";
       }
-      screens += *i;
+      screens += i;
       screens += ":";
     }
   }
diff --git a/src/lib/deskflow/KeyMap.cpp b/src/lib/deskflow/KeyMap.cpp
index 8401cdf6e..072e4b9d9 100644
--- a/src/lib/deskflow/KeyMap.cpp
+++ b/src/lib/deskflow/KeyMap.cpp
@@ -79,8 +79,8 @@ void KeyMap::addKeyEntry(const KeyItem &item)
 
   // see if we already have this item;  just return if so
   KeyEntryList &entries = groupTable[item.m_group];
-  for (size_t i = 0, n = entries.size(); i < n; ++i) {
-    if (entries[i].size() == 1 && newItem == entries[i][0]) {
+  for (const auto &entry : entries) {
+    if (entry.size() == 1 && newItem == entry.at(0)) {
       return;
     }
   }
@@ -157,10 +157,10 @@ bool KeyMap::addKeyCombinationEntry(KeyID id, int32_t group, const KeyID *keys,
     for (int32_t gd = 0; gd < n && !found; ++gd) {
       const auto eg = (group + gd) % getNumGroups();
       const KeyEntryList &entries = groupTable[eg];
-      for (size_t j = 0; j < entries.size(); ++j) {
-        if (entries[j].size() == 1) {
+      for (const auto &entry : entries) {
+        if (entry.size() == 1) {
           found = true;
-          items.push_back(entries[j][0]);
+          items.push_back(entry.at(0));
           break;
         }
       }
@@ -211,14 +211,14 @@ void KeyMap::finish()
 
 void KeyMap::foreachKey(ForeachKeyCallback cb, void *userData)
 {
-  for (auto i = m_keyIDMap.begin(); i != m_keyIDMap.end(); ++i) {
-    KeyGroupTable &groupTable = i->second;
+  for (const auto &[keyId, keyGroup] : m_keyIDMap) {
+    const KeyGroupTable &groupTable = keyGroup;
     for (size_t group = 0; group < groupTable.size(); ++group) {
-      KeyEntryList &entryList = groupTable[group];
-      for (size_t j = 0; j < entryList.size(); ++j) {
-        KeyItemList &itemList = entryList[j];
-        for (size_t k = 0; k < itemList.size(); ++k) {
-          (*cb)(i->first, static_cast<int32_t>(group), itemList[k], userData);
+      const KeyEntryList &entryList = groupTable.at(group);
+      for (auto &entry : entryList) {
+        const KeyItemList &itemList = entry;
+        for (auto item : itemList) {
+          (*cb)(keyId, static_cast<int32_t>(group), item, userData);
         }
       }
     }
@@ -334,10 +334,10 @@ KeyMap::findCompatibleKey(KeyID id, int32_t group, KeyModifierMask required, Key
   }
 
   const KeyEntryList &entries = i->second[group];
-  for (size_t j = 0; j < entries.size(); ++j) {
-    if ((entries[j].back().m_sensitive & sensitive) == 0 ||
-        (entries[j].back().m_required & sensitive) == (required & sensitive)) {
-      return &entries[j];
+  for (const auto &entry : entries) {
+    if ((entry.back().m_sensitive & sensitive) == 0 ||
+        (entry.back().m_required & sensitive) == (required & sensitive)) {
+      return &entry;
     }
   }
 
@@ -365,8 +365,8 @@ KeyModifierMask KeyMap::getCommandModifiers() const
 void KeyMap::collectButtons(const ModifierToKeys &mods, ButtonToKeyMap &keys)
 {
   keys.clear();
-  for (auto i = mods.begin(); i != mods.end(); ++i) {
-    keys.insert(std::make_pair(i->second.m_button, &i->second));
+  for (const auto &[modifierMask, keyItem] : mods) {
+    keys.insert(std::make_pair(keyItem.m_button, &keyItem));
   }
 }
 
@@ -440,18 +440,20 @@ void KeyMap::setModifierKeys()
 {
   m_modifierKeys.clear();
   m_modifierKeys.resize(kKeyModifierNumBits * getNumGroups());
-  for (KeyIDMap::const_iterator i = m_keyIDMap.begin(); i != m_keyIDMap.end(); ++i) {
-    const KeyGroupTable &groupTable = i->second;
-    for (size_t g = 0; g < groupTable.size(); ++g) {
-      const KeyEntryList &entries = groupTable[g];
-      for (size_t j = 0; j < entries.size(); ++j) {
+  for (const auto &[keyId, keyGroup] : m_keyIDMap) {
+    const KeyGroupTable &groupTable = keyGroup;
+    int32_t g = -1;
+    for (const auto &group : groupTable) {
+      g++;
+      const KeyEntryList &entries = group;
+      for (const auto &entry : entries) {
         // skip multi-key sequences
-        if (entries[j].size() != 1) {
+        if (entry.size() != 1) {
           continue;
         }
 
         // skip keys that don't generate a modifier
-        const KeyItem &item = entries[j].back();
+        const KeyItem &item = entry.back();
         if (item.m_generates == 0) {
           continue;
         }
@@ -460,7 +462,7 @@ void KeyMap::setModifierKeys()
         for (int32_t b = 0; b < kKeyModifierNumBits; ++b) {
           // skip if item doesn't generate bit b
           if (((1u << b) & item.m_generates) != 0) {
-            int32_t mIndex = (int32_t)g * kKeyModifierNumBits + b;
+            int32_t mIndex = g * kKeyModifierNumBits + b;
             m_modifierKeys[mIndex].push_back(&item);
           }
         }
@@ -602,8 +604,8 @@ const KeyMap::KeyItem *KeyMap::mapCharacterKey(
   int32_t newGroup = group;
 
   // add each key
-  for (size_t j = 0; j < itemList->size(); ++j) {
-    if (!keysForKeyItem(itemList->at(j), newGroup, newModifiers, newState, desiredMask, 0, isAutoRepeat, keys, lang)) {
+  for (auto &item : *itemList) {
+    if (!keysForKeyItem(item, newGroup, newModifiers, newState, desiredMask, 0, isAutoRepeat, keys, lang)) {
       LOG((CLOG_DEBUG1 "can't map key"));
       keys.clear();
       return nullptr;
@@ -680,9 +682,9 @@ const KeyMap::KeyItem *KeyMap::keyForModifier(KeyButton button, int32_t group, i
   // this is important when a shift button is modified by shift;  we
   // must use the other shift button to do the shifting.
   const ModifierKeyItemList &items = m_modifierKeys[group * kKeyModifierNumBits + modifierBit];
-  for (auto i = items.begin(); i != items.end(); ++i) {
-    if ((*i)->m_button != button) {
-      return (*i);
+  for (const auto &item : items) {
+    if (item->m_button != button) {
+      return item;
     }
   }
   return nullptr;
diff --git a/src/lib/deskflow/KeyState.cpp b/src/lib/deskflow/KeyState.cpp
index 951afd4c4..37c368d26 100644
--- a/src/lib/deskflow/KeyState.cpp
+++ b/src/lib/deskflow/KeyState.cpp
@@ -756,8 +756,8 @@ void KeyState::updateKeyState()
   // get the current keyboard state
   KeyButtonSet keysDown;
   pollPressedKeys(keysDown);
-  for (auto i = keysDown.begin(); i != keysDown.end(); ++i) {
-    m_keys[*i] = 1;
+  for (const auto &key : keysDown) {
+    m_keys[key] = 1;
   }
 
   // get the current modifier state
@@ -872,9 +872,9 @@ bool KeyState::fakeKeyRepeat(KeyID id, KeyModifierMask mask, int32_t count, KeyB
   if (localID != oldLocalID) {
     // replace key up with previous KeyButton but leave key down
     // alone so it uses the new KeyButton.
-    for (auto index = keys.begin(); index != keys.end(); ++index) {
-      if (index->m_type == Keystroke::kButton && index->m_data.m_button.m_button == localID) {
-        index->m_data.m_button.m_button = oldLocalID;
+    for (auto &key : keys) {
+      if (key.m_type == Keystroke::kButton && key.m_data.m_button.m_button == localID) {
+        key.m_data.m_button.m_button = oldLocalID;
         break;
       }
     }
@@ -1099,11 +1099,11 @@ void KeyState::updateModifierKeyState(
   // get the pressed modifier buttons before and after
   deskflow::KeyMap::ButtonToKeyMap oldKeys;
   deskflow::KeyMap::ButtonToKeyMap newKeys;
-  for (auto i = oldModifiers.begin(); i != oldModifiers.end(); ++i) {
-    oldKeys.insert(std::make_pair(i->second.m_button, &i->second));
+  for (const auto &[modifier, keyItem] : oldModifiers) {
+    oldKeys.insert(std::make_pair(keyItem.m_button, &keyItem));
   }
-  for (auto i = newModifiers.begin(); i != newModifiers.end(); ++i) {
-    newKeys.insert(std::make_pair(i->second.m_button, &i->second));
+  for (const auto &[modifier, keyItem] : newModifiers) {
+    newKeys.insert(std::make_pair(keyItem.m_button, &keyItem));
   }
 
   // get the modifier buttons that were pressed or released
diff --git a/src/lib/net/SecureUtils.cpp b/src/lib/net/SecureUtils.cpp
index 74f7a8c11..8ad24e56e 100644
--- a/src/lib/net/SecureUtils.cpp
+++ b/src/lib/net/SecureUtils.cpp
@@ -209,13 +209,12 @@ QString generateFingerprintArt(const QByteArray &rawDigest)
   int y = rows / 2;
 
   /* process raw key */
-  for (size_t i = 0; i < rawDigest.size(); i++) {
+  for (int byte : rawDigest) {
     /* each byte conveys four 2-bit move commands */
-    int input = rawDigest[i];
     for (uint32_t b = 0; b < 4; b++) {
       /* evaluate 2 bit, rest is shifted later */
-      x += (input & 0x1) ? 1 : -1;
-      y += (input & 0x2) ? 1 : -1;
+      x += (byte & 0x1) ? 1 : -1;
+      y += (byte & 0x2) ? 1 : -1;
 
       /* assure we are still in bounds */
       x = std::clamp(x, 0, columns - 1);
@@ -224,7 +223,7 @@ QString generateFingerprintArt(const QByteArray &rawDigest)
       /* augment the field */
       if (field[x][y] < len - 2)
         field[x][y]++;
-      input = input >> 2;
+      byte = byte >> 2;
     }
   }
 
diff --git a/src/lib/platform/XWindowsClipboard.cpp b/src/lib/platform/XWindowsClipboard.cpp
index 8ced66459..07470c9f6 100644
--- a/src/lib/platform/XWindowsClipboard.cpp
+++ b/src/lib/platform/XWindowsClipboard.cpp
@@ -1063,8 +1063,8 @@ void XWindowsClipboard::clearReplies()
 
 void XWindowsClipboard::clearReplies(ReplyList &replies)
 {
-  for (auto index = replies.begin(); index != replies.end(); ++index) {
-    delete *index;
+  for (auto reply : replies) {
+    delete reply;
   }
   replies.clear();
 }
diff --git a/src/lib/platform/XWindowsEventQueueBuffer.cpp b/src/lib/platform/XWindowsEventQueueBuffer.cpp
index 1d2c13c5a..942034fca 100644
--- a/src/lib/platform/XWindowsEventQueueBuffer.cpp
+++ b/src/lib/platform/XWindowsEventQueueBuffer.cpp
@@ -210,8 +210,8 @@ void XWindowsEventQueueBuffer::flush()
   // note -- m_mutex must be locked on entry
 
   // flush the posted event list to the X server
-  for (size_t i = 0; i < m_postedEvents.size(); ++i) {
-    XSendEvent(m_display, m_window, False, 0, &m_postedEvents[i]);
+  for (auto &event : m_postedEvents) {
+    XSendEvent(m_display, m_window, False, 0, &event);
   }
   XFlush(m_display);
   m_postedEvents.clear();
diff --git a/src/lib/platform/XWindowsScreen.cpp b/src/lib/platform/XWindowsScreen.cpp
index 0f19f1e19..1afdfa703 100644
--- a/src/lib/platform/XWindowsScreen.cpp
+++ b/src/lib/platform/XWindowsScreen.cpp
@@ -200,8 +200,8 @@ XWindowsScreen::~XWindowsScreen()
 
   m_events->adoptBuffer(nullptr);
   m_events->removeHandler(EventTypes::System, m_events->getSystemTarget());
-  for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
-    delete m_clipboard[id];
+  for (auto clipboard : m_clipboard) {
+    delete clipboard;
   }
   delete m_keyState;
   delete m_screensaver;
@@ -700,9 +700,9 @@ uint32_t XWindowsScreen::registerHotKey(KeyID key, KeyModifierMask mask)
 
   if (err) {
     // if any failed then unregister any we did get
-    for (auto j = hotKeys.begin(); j != hotKeys.end(); ++j) {
-      XUngrabKey(m_display, j->first, j->second, m_root);
-      m_hotKeyToIDMap.erase(HotKeyItem(j->first, j->second));
+    for (const auto &[keyCode, keyMask] : hotKeys) {
+      XUngrabKey(m_display, keyCode, keyMask, m_root);
+      m_hotKeyToIDMap.erase(HotKeyItem(keyCode, keyMask));
     }
 
     m_oldHotKeyIDs.push_back(id);
@@ -733,10 +733,10 @@ void XWindowsScreen::unregisterHotKey(uint32_t id)
   bool err = false;
   {
     XWindowsUtil::ErrorLock lock(m_display, &err);
-    HotKeyList &hotKeys = i->second;
-    for (auto j = hotKeys.begin(); j != hotKeys.end(); ++j) {
-      XUngrabKey(m_display, j->first, j->second, m_root);
-      m_hotKeyToIDMap.erase(HotKeyItem(j->first, j->second));
+    const HotKeyList &hotKeys = i->second;
+    for (const auto &[keyCode, keyMask] : hotKeys) {
+      XUngrabKey(m_display, keyCode, keyMask, m_root);
+      m_hotKeyToIDMap.erase(HotKeyItem(keyCode, keyMask));
     }
   }
   if (err) {
@@ -1644,8 +1644,8 @@ ClipboardID XWindowsScreen::getClipboardID(Atom selection) const
 void XWindowsScreen::processClipboardRequest(Window requestor, Time time, Atom property) const
 {
   // check every clipboard until one returns success
-  for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
-    if (m_clipboard[id] != nullptr && m_clipboard[id]->processRequest(requestor, time, property)) {
+  for (const auto &clipboard : m_clipboard) {
+    if (clipboard != nullptr && clipboard->processRequest(requestor, time, property)) {
       break;
     }
   }
@@ -1654,8 +1654,8 @@ void XWindowsScreen::processClipboardRequest(Window requestor, Time time, Atom p
 void XWindowsScreen::destroyClipboardRequest(Window requestor) const
 {
   // check every clipboard until one returns success
-  for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
-    if (m_clipboard[id] != nullptr && m_clipboard[id]->destroyRequest(requestor)) {
+  for (const auto &clipboard : m_clipboard) {
+    if (clipboard != nullptr && clipboard->destroyRequest(requestor)) {
       break;
     }
   }
diff --git a/src/lib/server/Config.cpp b/src/lib/server/Config.cpp
index 344c36b69..1be7b9ec5 100644
--- a/src/lib/server/Config.cpp
+++ b/src/lib/server/Config.cpp
@@ -1599,13 +1599,13 @@ std::ostream &operator<<(std::ostream &s, const Config &config)
 {
   // screens section
   s << "section: screens" << std::endl;
-  for (auto screen = config.begin(); screen != config.end(); ++screen) {
-    s << "\t" << screen->c_str() << ":" << std::endl;
-    const Config::ScreenOptions *options = config.getOptions(*screen);
+  for (const auto &screen : config) {
+    s << "\t" << screen.c_str() << ":" << std::endl;
+    const auto options = config.getOptions(screen);
     if (options != nullptr && options->size() > 0) {
-      for (auto option = options->begin(); option != options->end(); ++option) {
-        const char *name = Config::getOptionName(option->first);
-        std::string value = Config::getOptionValue(option->first, option->second);
+      for (auto [optionId, optionValue] : *options) {
+        const char *name = Config::getOptionName(optionId);
+        std::string value = Config::getOptionValue(optionId, optionValue);
         if (name != nullptr && !value.empty()) {
           s << "\t\t" << name << " = " << value << std::endl;
         }
@@ -1617,10 +1617,10 @@ std::ostream &operator<<(std::ostream &s, const Config &config)
   // links section
   std::string neighbor;
   s << "section: links" << std::endl;
-  for (auto screen = config.begin(); screen != config.end(); ++screen) {
-    s << "\t" << screen->c_str() << ":" << std::endl;
+  for (const auto &screen : config) {
+    s << "\t" << screen.c_str() << ":" << std::endl;
 
-    for (Config::link_const_iterator link = config.beginNeighbor(*screen), nend = config.endNeighbor(*screen);
+    for (Config::link_const_iterator link = config.beginNeighbor(screen), nend = config.endNeighbor(screen);
          link != nend; ++link) {
       s << "\t\t" << Config::dirName(link->first.getSide()) << Config::formatInterval(link->first.getInterval())
         << " = " << link->second.getName().c_str() << Config::formatInterval(link->second.getInterval()) << std::endl;
@@ -1655,9 +1655,9 @@ std::ostream &operator<<(std::ostream &s, const Config &config)
   // options section
   s << "section: options" << std::endl;
   if (const Config::ScreenOptions *options = config.getOptions(""); options && options->size() > 0) {
-    for (auto option = options->begin(); option != options->end(); ++option) {
-      const char *name = Config::getOptionName(option->first);
-      std::string value = Config::getOptionValue(option->first, option->second);
+    for (auto [optionId, optionValue] : *options) {
+      const char *name = Config::getOptionName(optionId);
+      std::string value = Config::getOptionValue(optionId, optionValue);
       if (name != nullptr && !value.empty()) {
         s << "\t" << name << " = " << value << std::endl;
       }
diff --git a/src/lib/server/InputFilter.cpp b/src/lib/server/InputFilter.cpp
index 0d81ef852..0ebcc3fe0 100644
--- a/src/lib/server/InputFilter.cpp
+++ b/src/lib/server/InputFilter.cpp
@@ -662,9 +662,9 @@ bool InputFilter::Rule::handleEvent(const Event &event)
   }
 
   // perform actions
-  for (auto i = actions->begin(); i != actions->end(); ++i) {
-    LOG((CLOG_DEBUG1 "hotkey: %s", (*i)->format().c_str()));
-    (*i)->perform(event);
+  for (auto action : *actions) {
+    LOG((CLOG_DEBUG1 "hotkey: %s", action->format().c_str()));
+    action->perform(event);
   }
 
   return true;
diff --git a/src/lib/server/PrimaryClient.cpp b/src/lib/server/PrimaryClient.cpp
index 4e6c18919..cc97b8672 100644
--- a/src/lib/server/PrimaryClient.cpp
+++ b/src/lib/server/PrimaryClient.cpp
@@ -20,10 +20,7 @@ PrimaryClient::PrimaryClient(const std::string &name, deskflow::Screen *screen)
       m_screen(screen),
       m_fakeInputCount(0)
 {
-  // all clipboards are clean
-  for (uint32_t i = 0; i < kClipboardEnd; ++i) {
-    m_clipboardDirty[i] = false;
-  }
+  // do nothing
 }
 
 void PrimaryClient::reconfigure(uint32_t activeSides)
diff --git a/src/lib/server/PrimaryClient.h b/src/lib/server/PrimaryClient.h
index 7f8045a83..da60fa0ce 100644
--- a/src/lib/server/PrimaryClient.h
+++ b/src/lib/server/PrimaryClient.h
@@ -142,6 +142,6 @@ public:
 
 private:
   deskflow::Screen *m_screen;
-  bool m_clipboardDirty[kClipboardEnd];
+  bool m_clipboardDirty[kClipboardEnd] = {false, false};
   int32_t m_fakeInputCount;
 };
diff --git a/src/lib/server/Server.cpp b/src/lib/server/Server.cpp
index e931752d2..1d6fb5fef 100644
--- a/src/lib/server/Server.cpp
+++ b/src/lib/server/Server.cpp
@@ -83,8 +83,7 @@ Server::Server(
   std::string primaryName = getName(primaryClient);
 
   // clear clipboards
-  for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
-    ClipboardInfo &clipboard = m_clipboards[id];
+  for (auto &clipboard : m_clipboards) {
     clipboard.m_clipboardOwner = primaryName;
     clipboard.m_clipboardSeqNum = m_seqNum;
     if (clipboard.m_clipboard.open(0)) {
@@ -1062,9 +1061,9 @@ void Server::sendOptions(BaseClientProxy *client) const
   if (options != nullptr) {
     // convert options to a more convenient form for sending
     optionsList.reserve(2 * options->size());
-    for (auto index = options->begin(); index != options->end(); ++index) {
-      optionsList.push_back(index->first);
-      optionsList.push_back(static_cast<uint32_t>(index->second));
+    for (auto [optionId, optionValue] : *options) {
+      optionsList.push_back(optionId);
+      optionsList.push_back(static_cast<uint32_t>(optionValue));
     }
   }
 
@@ -1073,9 +1072,9 @@ void Server::sendOptions(BaseClientProxy *client) const
   if (options != nullptr) {
     // convert options to a more convenient form for sending
     optionsList.reserve(optionsList.size() + 2 * options->size());
-    for (auto index = options->begin(); index != options->end(); ++index) {
-      optionsList.push_back(index->first);
-      optionsList.push_back(static_cast<uint32_t>(index->second));
+    for (auto [optionId, optionValue] : *options) {
+      optionsList.push_back(optionId);
+      optionsList.push_back(static_cast<uint32_t>(optionValue));
     }
   }
 
@@ -1096,9 +1095,9 @@ void Server::processOptions()
   m_switchNeedsAlt = false;     // doesnt' work correct.
 
   bool newRelativeMoves = m_relativeMoves;
-  for (auto index = options->begin(); index != options->end(); ++index) {
-    const OptionID id = index->first;
-    const OptionValue value = index->second;
+  for (auto [optionId, optionValue] : *options) {
+    const OptionID id = optionId;
+    const OptionValue value = optionValue;
     if (id == kOptionProtocol) {
       using enum ENetworkProtocol;
       const auto enumValue = static_cast<ENetworkProtocol>(value);
@@ -2010,8 +2009,8 @@ void Server::closeClients(const ServerConfig &config)
 
   // now close them.  we collect the list then close in two steps
   // because closeClient() modifies the collection we iterate over.
-  for (auto index = removed.begin(); index != removed.end(); ++index) {
-    closeClient(*index, kMsgCClose);
+  for (auto &client : removed) {
+    closeClient(client, kMsgCClose);
   }
 }