diff --git a/atom/app/uv_task_runner.cc b/atom/app/uv_task_runner.cc
index 097cc3bcda1..7857ace3a2b 100644
--- a/atom/app/uv_task_runner.cc
+++ b/atom/app/uv_task_runner.cc
@@ -21,7 +21,7 @@ UvTaskRunner::~UvTaskRunner() {
 bool UvTaskRunner::PostDelayedTask(const tracked_objects::Location& from_here,
                                    const base::Closure& task,
                                    base::TimeDelta delay) {
-  uv_timer_t* timer = new uv_timer_t;
+  auto* timer = new uv_timer_t;
   timer->data = this;
   uv_timer_init(loop_, timer);
   uv_timer_start(timer, UvTaskRunner::OnTimeout, delay.InMilliseconds(), 0);
diff --git a/atom/browser/api/atom_api_menu.cc b/atom/browser/api/atom_api_menu.cc
index 5e66850c754..54a3d4e8132 100644
--- a/atom/browser/api/atom_api_menu.cc
+++ b/atom/browser/api/atom_api_menu.cc
@@ -21,7 +21,7 @@ namespace api {
 
 Menu::Menu(v8::Isolate* isolate)
     : model_(new AtomMenuModel(this)),
-      parent_(NULL) {
+      parent_(nullptr) {
 }
 
 Menu::~Menu() {
diff --git a/atom/browser/api/atom_api_session.cc b/atom/browser/api/atom_api_session.cc
index 4a4ffba0c84..c898f5f1b33 100644
--- a/atom/browser/api/atom_api_session.cc
+++ b/atom/browser/api/atom_api_session.cc
@@ -241,10 +241,10 @@ void OnGetBackend(disk_cache::Backend** backend_ptr,
     } else if (action == Session::CacheAction::STATS) {
       base::StringPairs stats;
       (*backend_ptr)->GetStats(&stats);
-      for (size_t i = 0; i < stats.size(); ++i) {
-        if (stats[i].first == "Current size") {
+      for (const auto& stat : stats) {
+        if (stat.first == "Current size") {
           int current_size;
-          base::StringToInt(stats[i].second, &current_size);
+          base::StringToInt(stat.second, &current_size);
           RunCallbackInUI(callback, current_size);
           break;
         }
@@ -266,7 +266,7 @@ void DoCacheActionInIO(
 
   // Call GetBackend and make the backend's ptr accessable in OnGetBackend.
   using BackendPtr = disk_cache::Backend*;
-  BackendPtr* backend_ptr = new BackendPtr(nullptr);
+  auto* backend_ptr = new BackendPtr(nullptr);
   net::CompletionCallback on_get_backend =
       base::Bind(&OnGetBackend, base::Owned(backend_ptr), action, callback);
   int rv = http_cache->GetBackend(backend_ptr, on_get_backend);
diff --git a/atom/browser/api/atom_api_web_contents.cc b/atom/browser/api/atom_api_web_contents.cc
index 2b1d03dbd27..8622942668b 100644
--- a/atom/browser/api/atom_api_web_contents.cc
+++ b/atom/browser/api/atom_api_web_contents.cc
@@ -685,10 +685,10 @@ void WebContents::TitleWasSet(content::NavigationEntry* entry,
 void WebContents::DidUpdateFaviconURL(
     const std::vector<content::FaviconURL>& urls) {
   std::set<GURL> unique_urls;
-  for (auto iter = urls.begin(); iter != urls.end(); ++iter) {
-    if (iter->icon_type != content::FaviconURL::FAVICON)
+  for (const auto& iter : urls) {
+    if (iter.icon_type != content::FaviconURL::FAVICON)
       continue;
-    const GURL& url = iter->icon_url;
+    const GURL& url = iter.icon_url;
     if (url.is_valid())
       unique_urls.insert(url);
   }
diff --git a/atom/browser/api/event.cc b/atom/browser/api/event.cc
index 2554e4ad0da..8c60eda2471 100644
--- a/atom/browser/api/event.cc
+++ b/atom/browser/api/event.cc
@@ -12,8 +12,8 @@
 namespace mate {
 
 Event::Event(v8::Isolate* isolate)
-    : sender_(NULL),
-      message_(NULL) {
+    : sender_(nullptr),
+      message_(nullptr) {
   Init(isolate);
 }
 
@@ -31,8 +31,8 @@ void Event::SetSenderAndMessage(content::WebContents* sender,
 }
 
 void Event::WebContentsDestroyed() {
-  sender_ = NULL;
-  message_ = NULL;
+  sender_ = nullptr;
+  message_ = nullptr;
 }
 
 void Event::PreventDefault(v8::Isolate* isolate) {
@@ -41,13 +41,13 @@ void Event::PreventDefault(v8::Isolate* isolate) {
 }
 
 bool Event::SendReply(const base::string16& json) {
-  if (message_ == NULL || sender_ == NULL)
+  if (message_ == nullptr || sender_ == nullptr)
     return false;
 
   AtomViewHostMsg_Message_Sync::WriteReplyParams(message_, json);
   bool success = sender_->Send(message_);
-  message_ = NULL;
-  sender_ = NULL;
+  message_ = nullptr;
+  sender_ = nullptr;
   return success;
 }
 
diff --git a/atom/browser/atom_browser_main_parts.cc b/atom/browser/atom_browser_main_parts.cc
index b933d1073bb..66c1bd8303a 100644
--- a/atom/browser/atom_browser_main_parts.cc
+++ b/atom/browser/atom_browser_main_parts.cc
@@ -32,7 +32,7 @@ void Erase(T* container, typename T::iterator iter) {
 }
 
 // static
-AtomBrowserMainParts* AtomBrowserMainParts::self_ = NULL;
+AtomBrowserMainParts* AtomBrowserMainParts::self_ = nullptr;
 
 AtomBrowserMainParts::AtomBrowserMainParts()
     : fake_browser_process_(new BrowserProcess),
diff --git a/atom/browser/atom_browser_main_parts_posix.cc b/atom/browser/atom_browser_main_parts_posix.cc
index 2a0dddc4748..8c96f91bfe6 100644
--- a/atom/browser/atom_browser_main_parts_posix.cc
+++ b/atom/browser/atom_browser_main_parts_posix.cc
@@ -43,7 +43,7 @@ void GracefulShutdownHandler(int signal) {
   struct sigaction action;
   memset(&action, 0, sizeof(action));
   action.sa_handler = SIG_DFL;
-  RAW_CHECK(sigaction(signal, &action, NULL) == 0);
+  RAW_CHECK(sigaction(signal, &action, nullptr) == 0);
 
   RAW_CHECK(g_pipe_pid == getpid());
   RAW_CHECK(g_shutdown_pipe_write_fd != -1);
@@ -171,7 +171,7 @@ void AtomBrowserMainParts::HandleSIGCHLD() {
   struct sigaction action;
   memset(&action, 0, sizeof(action));
   action.sa_handler = SIGCHLDHandler;
-  CHECK_EQ(sigaction(SIGCHLD, &action, NULL), 0);
+  CHECK_EQ(sigaction(SIGCHLD, &action, nullptr), 0);
 }
 
 void AtomBrowserMainParts::HandleShutdownSignals() {
@@ -211,15 +211,15 @@ void AtomBrowserMainParts::HandleShutdownSignals() {
   struct sigaction action;
   memset(&action, 0, sizeof(action));
   action.sa_handler = SIGTERMHandler;
-  CHECK_EQ(sigaction(SIGTERM, &action, NULL), 0);
+  CHECK_EQ(sigaction(SIGTERM, &action, nullptr), 0);
   // Also handle SIGINT - when the user terminates the browser via Ctrl+C. If
   // the browser process is being debugged, GDB will catch the SIGINT first.
   action.sa_handler = SIGINTHandler;
-  CHECK_EQ(sigaction(SIGINT, &action, NULL), 0);
+  CHECK_EQ(sigaction(SIGINT, &action, nullptr), 0);
   // And SIGHUP, for when the terminal disappears. On shutdown, many Linux
   // distros send SIGHUP, SIGTERM, and then SIGKILL.
   action.sa_handler = SIGHUPHandler;
-  CHECK_EQ(sigaction(SIGHUP, &action, NULL), 0);
+  CHECK_EQ(sigaction(SIGHUP, &action, nullptr), 0);
 }
 
 }  // namespace atom
diff --git a/atom/browser/common_web_contents_delegate.cc b/atom/browser/common_web_contents_delegate.cc
index c275d4aee74..f2f0ee8aec5 100644
--- a/atom/browser/common_web_contents_delegate.cc
+++ b/atom/browser/common_web_contents_delegate.cc
@@ -94,7 +94,7 @@ FileSystem CreateFileSystemStruct(
 }
 
 base::DictionaryValue* CreateFileSystemValue(const FileSystem& file_system) {
-  base::DictionaryValue* file_system_value = new base::DictionaryValue();
+  auto* file_system_value = new base::DictionaryValue();
   file_system_value->SetString("fileSystemName", file_system.file_system_name);
   file_system_value->SetString("rootURL", file_system.root_url);
   file_system_value->SetString("fileSystemPath", file_system.file_system_path);
@@ -377,7 +377,7 @@ content::SecurityStyle CommonWebContentsDelegate::GetSecurityStyle(
 void CommonWebContentsDelegate::DevToolsSaveToFile(
     const std::string& url, const std::string& content, bool save_as) {
   base::FilePath path;
-  PathsMap::iterator it = saved_files_.find(url);
+  auto it = saved_files_.find(url);
   if (it != saved_files_.end() && !save_as) {
     path = it->second;
   } else {
@@ -402,7 +402,7 @@ void CommonWebContentsDelegate::DevToolsSaveToFile(
 
 void CommonWebContentsDelegate::DevToolsAppendToFile(
     const std::string& url, const std::string& content) {
-  PathsMap::iterator it = saved_files_.find(url);
+  auto it = saved_files_.find(url);
   if (it == saved_files_.end())
     return;
 
@@ -435,8 +435,8 @@ void CommonWebContentsDelegate::DevToolsRequestFileSystems() {
   }
 
   base::ListValue file_system_value;
-  for (size_t i = 0; i < file_systems.size(); ++i)
-    file_system_value.Append(CreateFileSystemValue(file_systems[i]));
+  for (const auto& file_system : file_systems)
+    file_system_value.Append(CreateFileSystemValue(file_system));
   web_contents_->CallClientFunction("DevToolsAPI.fileSystemsLoaded",
                                     &file_system_value, nullptr, nullptr);
 }
@@ -610,9 +610,8 @@ void CommonWebContentsDelegate::OnDevToolsSearchCompleted(
     const std::string& file_system_path,
     const std::vector<std::string>& file_paths) {
   base::ListValue file_paths_value;
-  for (std::vector<std::string>::const_iterator it(file_paths.begin());
-       it != file_paths.end(); ++it) {
-    file_paths_value.AppendString(*it);
+  for (const auto& file_path : file_paths) {
+    file_paths_value.AppendString(file_path);
   }
   base::FundamentalValue request_id_value(request_id);
   base::StringValue file_system_path_value(file_system_path);
diff --git a/atom/browser/net/asar/asar_protocol_handler.cc b/atom/browser/net/asar/asar_protocol_handler.cc
index 324f8339c8c..ffa2b3c9f28 100644
--- a/atom/browser/net/asar/asar_protocol_handler.cc
+++ b/atom/browser/net/asar/asar_protocol_handler.cc
@@ -22,7 +22,7 @@ net::URLRequestJob* AsarProtocolHandler::MaybeCreateJob(
     net::NetworkDelegate* network_delegate) const {
   base::FilePath full_path;
   net::FileURLToFilePath(request->url(), &full_path);
-  URLRequestAsarJob* job = new URLRequestAsarJob(request, network_delegate);
+  auto* job = new URLRequestAsarJob(request, network_delegate);
   job->Initialize(file_task_runner_, full_path);
   return job;
 }
diff --git a/atom/browser/net/asar/url_request_asar_job.cc b/atom/browser/net/asar/url_request_asar_job.cc
index 39e55a35cbc..2352668e179 100644
--- a/atom/browser/net/asar/url_request_asar_job.cc
+++ b/atom/browser/net/asar/url_request_asar_job.cc
@@ -111,7 +111,7 @@ void URLRequestAsarJob::Start() {
     if (rv != net::ERR_IO_PENDING)
       DidOpen(rv);
   } else if (type_ == TYPE_FILE) {
-    FileMetaInfo* meta_info = new FileMetaInfo();
+    auto* meta_info = new FileMetaInfo();
     file_task_runner_->PostTaskAndReply(
         FROM_HERE,
         base::Bind(&URLRequestAsarJob::FetchMetaInfo, file_path_,
@@ -183,7 +183,7 @@ bool URLRequestAsarJob::IsRedirectResponse(GURL* location,
 net::Filter* URLRequestAsarJob::SetupFilter() const {
   // Bug 9936 - .svgz files needs to be decompressed.
   return base::LowerCaseEqualsASCII(file_path_.Extension(), ".svgz")
-      ? net::Filter::GZipFactory() : NULL;
+      ? net::Filter::GZipFactory() : nullptr;
 }
 
 bool URLRequestAsarJob::GetMimeType(std::string* mime_type) const {
@@ -224,7 +224,7 @@ int URLRequestAsarJob::GetResponseCode() const {
 
 void URLRequestAsarJob::GetResponseInfo(net::HttpResponseInfo* info) {
   std::string status("HTTP/1.1 200 OK");
-  net::HttpResponseHeaders* headers = new net::HttpResponseHeaders(status);
+  auto* headers = new net::HttpResponseHeaders(status);
 
   headers->AddHeader(atom::kCORSHeader);
   info->headers = headers;
@@ -338,7 +338,7 @@ void URLRequestAsarJob::DidRead(scoped_refptr<net::IOBuffer> buf, int result) {
     DCHECK_GE(remaining_bytes_, 0);
   }
 
-  buf = NULL;
+  buf = nullptr;
 
   ReadRawDataComplete(result);
 }
diff --git a/atom/browser/net/atom_url_request_job_factory.cc b/atom/browser/net/atom_url_request_job_factory.cc
index d0caf183e91..7e2eb95149c 100644
--- a/atom/browser/net/atom_url_request_job_factory.cc
+++ b/atom/browser/net/atom_url_request_job_factory.cc
@@ -27,7 +27,7 @@ bool AtomURLRequestJobFactory::SetProtocolHandler(
     const std::string& scheme,
     std::unique_ptr<ProtocolHandler> protocol_handler) {
   if (!protocol_handler) {
-    ProtocolHandlerMap::iterator it = protocol_handler_map_.find(scheme);
+    auto it = protocol_handler_map_.find(scheme);
     if (it == protocol_handler_map_.end())
       return false;
 
@@ -66,7 +66,7 @@ ProtocolHandler* AtomURLRequestJobFactory::GetProtocolHandler(
     const std::string& scheme) const {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  ProtocolHandlerMap::const_iterator it = protocol_handler_map_.find(scheme);
+  auto it = protocol_handler_map_.find(scheme);
   if (it == protocol_handler_map_.end())
     return nullptr;
   return it->second;
@@ -87,7 +87,7 @@ net::URLRequestJob* AtomURLRequestJobFactory::MaybeCreateJobWithProtocolHandler(
     net::NetworkDelegate* network_delegate) const {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  ProtocolHandlerMap::const_iterator it = protocol_handler_map_.find(scheme);
+  auto it = protocol_handler_map_.find(scheme);
   if (it == protocol_handler_map_.end())
     return nullptr;
   return it->second->MaybeCreateJob(request, network_delegate);
diff --git a/atom/browser/net/url_request_async_asar_job.cc b/atom/browser/net/url_request_async_asar_job.cc
index 1234bccf430..942f06233e3 100644
--- a/atom/browser/net/url_request_async_asar_job.cc
+++ b/atom/browser/net/url_request_async_asar_job.cc
@@ -40,7 +40,7 @@ void URLRequestAsyncAsarJob::StartAsync(std::unique_ptr<base::Value> options) {
 
 void URLRequestAsyncAsarJob::GetResponseInfo(net::HttpResponseInfo* info) {
   std::string status("HTTP/1.1 200 OK");
-  net::HttpResponseHeaders* headers = new net::HttpResponseHeaders(status);
+  auto* headers = new net::HttpResponseHeaders(status);
 
   headers->AddHeader(kCORSHeader);
   info->headers = headers;
diff --git a/atom/browser/net/url_request_buffer_job.cc b/atom/browser/net/url_request_buffer_job.cc
index c713099c76a..70f46030817 100644
--- a/atom/browser/net/url_request_buffer_job.cc
+++ b/atom/browser/net/url_request_buffer_job.cc
@@ -72,7 +72,7 @@ void URLRequestBufferJob::GetResponseInfo(net::HttpResponseInfo* info) {
   status.append(" ");
   status.append(net::GetHttpReasonPhrase(status_code_));
   status.append("\0\0", 2);
-  net::HttpResponseHeaders* headers = new net::HttpResponseHeaders(status);
+  auto* headers = new net::HttpResponseHeaders(status);
 
   headers->AddHeader(kCORSHeader);
 
diff --git a/atom/browser/net/url_request_string_job.cc b/atom/browser/net/url_request_string_job.cc
index 59945e66db0..abec345e63d 100644
--- a/atom/browser/net/url_request_string_job.cc
+++ b/atom/browser/net/url_request_string_job.cc
@@ -31,7 +31,7 @@ void URLRequestStringJob::StartAsync(std::unique_ptr<base::Value> options) {
 
 void URLRequestStringJob::GetResponseInfo(net::HttpResponseInfo* info) {
   std::string status("HTTP/1.1 200 OK");
-  net::HttpResponseHeaders* headers = new net::HttpResponseHeaders(status);
+  auto* headers = new net::HttpResponseHeaders(status);
 
   headers->AddHeader(kCORSHeader);
 
diff --git a/atom/browser/relauncher_mac.cc b/atom/browser/relauncher_mac.cc
index ef26f8441df..ac4c874c560 100644
--- a/atom/browser/relauncher_mac.cc
+++ b/atom/browser/relauncher_mac.cc
@@ -43,7 +43,7 @@ void RelauncherSynchronizeWithParent() {
 
   struct kevent change = { 0 };
   EV_SET(&change, parent_pid, EVFILT_PROC, EV_ADD, NOTE_EXIT, 0, NULL);
-  if (kevent(kq.get(), &change, 1, NULL, 0, NULL) == -1) {
+  if (kevent(kq.get(), &change, 1, nullptr, 0, nullptr) == -1) {
     PLOG(ERROR) << "kevent (add)";
     return;
   }
@@ -58,7 +58,7 @@ void RelauncherSynchronizeWithParent() {
   // write above to complete. The parent process is now free to exit. Wait for
   // that to happen.
   struct kevent event;
-  int events = kevent(kq.get(), NULL, 0, &event, 1, NULL);
+  int events = kevent(kq.get(), nullptr, 0, &event, 1, nullptr);
   if (events != 1) {
     if (events < 0) {
       PLOG(ERROR) << "kevent (monitor)";
diff --git a/atom/browser/ui/accelerator_util.cc b/atom/browser/ui/accelerator_util.cc
index 361cd88e05d..eb89bf0c35f 100644
--- a/atom/browser/ui/accelerator_util.cc
+++ b/atom/browser/ui/accelerator_util.cc
@@ -30,9 +30,9 @@ bool StringToAccelerator(const std::string& shortcut,
   // Now, parse it into an accelerator.
   int modifiers = ui::EF_NONE;
   ui::KeyboardCode key = ui::VKEY_UNKNOWN;
-  for (size_t i = 0; i < tokens.size(); i++) {
+  for (const auto& token : tokens) {
     bool shifted = false;
-    ui::KeyboardCode code = atom::KeyboardCodeFromStr(tokens[i], &shifted);
+    ui::KeyboardCode code = atom::KeyboardCodeFromStr(token, &shifted);
     if (shifted)
       modifiers |= ui::EF_SHIFT_DOWN;
     switch (code) {
diff --git a/atom/browser/window_list.cc b/atom/browser/window_list.cc
index b3bec5d08c1..83bf615aad2 100644
--- a/atom/browser/window_list.cc
+++ b/atom/browser/window_list.cc
@@ -17,7 +17,7 @@ base::LazyInstance<base::ObserverList<WindowListObserver>>::Leaky
     WindowList::observers_ = LAZY_INSTANCE_INITIALIZER;
 
 // static
-WindowList* WindowList::instance_ = NULL;
+WindowList* WindowList::instance_ = nullptr;
 
 // static
 WindowList* WindowList::GetInstance() {
@@ -70,8 +70,8 @@ void WindowList::RemoveObserver(WindowListObserver* observer) {
 // static
 void WindowList::CloseAllWindows() {
   WindowVector windows = GetInstance()->windows_;
-  for (size_t i = 0; i < windows.size(); ++i)
-    windows[i]->Close();
+  for (const auto& window : windows)
+    window->Close();
 }
 
 WindowList::WindowList() {
diff --git a/atom/common/api/atom_api_native_image.cc b/atom/common/api/atom_api_native_image.cc
index 14500496ebf..80275e26a7f 100644
--- a/atom/common/api/atom_api_native_image.cc
+++ b/atom/common/api/atom_api_native_image.cc
@@ -63,10 +63,10 @@ float GetScaleFactorFromPath(const base::FilePath& path) {
 
   // We don't try to convert string to float here because it is very very
   // expensive.
-  for (unsigned i = 0; i < node::arraysize(kScaleFactorPairs); ++i) {
-    if (base::EndsWith(filename, kScaleFactorPairs[i].name,
+  for (const auto& kScaleFactorPair : kScaleFactorPairs) {
+    if (base::EndsWith(filename, kScaleFactorPair.name,
                        base::CompareCase::INSENSITIVE_ASCII))
-      return kScaleFactorPairs[i].scale;
+      return kScaleFactorPair.scale;
   }
 
   return 1.0f;
diff --git a/atom/common/api/atom_bindings.cc b/atom/common/api/atom_bindings.cc
index 599fc674989..b5a51ad507e 100644
--- a/atom/common/api/atom_bindings.cc
+++ b/atom/common/api/atom_bindings.cc
@@ -25,7 +25,7 @@ namespace {
 struct DummyClass { bool crash; };
 
 void Crash() {
-  static_cast<DummyClass*>(NULL)->crash = true;
+  static_cast<DummyClass*>(nullptr)->crash = true;
 }
 
 void Hang() {
diff --git a/atom/common/asar/archive.cc b/atom/common/asar/archive.cc
index c2306c3c8f3..e622effe5d3 100644
--- a/atom/common/asar/archive.cc
+++ b/atom/common/asar/archive.cc
@@ -41,7 +41,7 @@ bool GetFilesNode(const base::DictionaryValue* root,
   // Test for symbol linked directory.
   std::string link;
   if (dir->GetStringWithoutPathExpansion("link", &link)) {
-    const base::DictionaryValue* linked_node = NULL;
+    const base::DictionaryValue* linked_node = nullptr;
     if (!GetNodeFromPath(link, root, &linked_node))
       return false;
     dir = linked_node;
@@ -60,7 +60,7 @@ bool GetChildNode(const base::DictionaryValue* root,
     return true;
   }
 
-  const base::DictionaryValue* files = NULL;
+  const base::DictionaryValue* files = nullptr;
   return GetFilesNode(root, dir, &files) &&
          files->GetDictionaryWithoutPathExpansion(name, out);
 }
@@ -78,7 +78,7 @@ bool GetNodeFromPath(std::string path,
   for (size_t delimiter_position = path.find_first_of(kSeparators);
        delimiter_position != std::string::npos;
        delimiter_position = path.find_first_of(kSeparators)) {
-    const base::DictionaryValue* child = NULL;
+    const base::DictionaryValue* child = nullptr;
     if (!GetChildNode(root, path.substr(0, delimiter_position), dir, &child))
       return false;
 
diff --git a/atom/common/native_mate_converters/callback.cc b/atom/common/native_mate_converters/callback.cc
index 8bf5c459b0a..dc6d30fd23d 100644
--- a/atom/common/native_mate_converters/callback.cc
+++ b/atom/common/native_mate_converters/callback.cc
@@ -123,7 +123,7 @@ v8::Local<v8::Value> CreateFunctionFromTranslater(
 
   v8::Local<v8::FunctionTemplate> call_translater =
       v8::Local<v8::FunctionTemplate>::New(isolate, g_call_translater);
-  TranslaterHolder* holder = new TranslaterHolder;
+  auto* holder = new TranslaterHolder;
   holder->translater = translater;
   return BindFunctionWith(isolate,
                           isolate->GetCurrentContext(),
diff --git a/atom/common/native_mate_converters/v8_value_converter.cc b/atom/common/native_mate_converters/v8_value_converter.cc
index ff96b727e02..37e09aec575 100644
--- a/atom/common/native_mate_converters/v8_value_converter.cc
+++ b/atom/common/native_mate_converters/v8_value_converter.cc
@@ -55,7 +55,7 @@ class V8ValueConverter::FromV8ValueState {
     // hash. Different hash obviously means different objects, but two objects
     // in a couple of thousands could have the same identity hash.
     std::pair<Iterator, Iterator> range = unique_map_.equal_range(hash);
-    for (Iterator it = range.first; it != range.second; ++it) {
+    for (auto it = range.first; it != range.second; ++it) {
       // Operator == for handles actually compares the underlying objects.
       if (it->second == handle)
         return false;
@@ -162,7 +162,7 @@ v8::Local<v8::Value> V8ValueConverter::ToV8Array(
   v8::Local<v8::Array> result(v8::Array::New(isolate, val->GetSize()));
 
   for (size_t i = 0; i < val->GetSize(); ++i) {
-    const base::Value* child = NULL;
+    const base::Value* child = nullptr;
     CHECK(val->Get(i, &child));
 
     v8::Local<v8::Value> child_v8 = ToV8ValueImpl(isolate, child);
@@ -214,7 +214,7 @@ base::Value* V8ValueConverter::FromV8ValueImpl(
 
   FromV8ValueState::Level state_level(state);
   if (state->HasReachedMaxRecursionDepth())
-    return NULL;
+    return nullptr;
 
   if (val->IsNull())
     return base::Value::CreateNullValue().release();
@@ -235,7 +235,7 @@ base::Value* V8ValueConverter::FromV8ValueImpl(
 
   if (val->IsUndefined())
     // JSON.stringify ignores undefined.
-    return NULL;
+    return nullptr;
 
   if (val->IsDate()) {
     v8::Date* date = v8::Date::Cast(*val);
@@ -265,7 +265,7 @@ base::Value* V8ValueConverter::FromV8ValueImpl(
   if (val->IsFunction()) {
     if (!function_allowed_)
       // JSON.stringify refuses to convert function(){}.
-      return NULL;
+      return nullptr;
     return FromV8Object(val->ToObject(), state, isolate);
   }
 
@@ -278,7 +278,7 @@ base::Value* V8ValueConverter::FromV8ValueImpl(
   }
 
   LOG(ERROR) << "Unexpected v8 value type encountered.";
-  return NULL;
+  return nullptr;
 }
 
 base::Value* V8ValueConverter::FromV8Array(
@@ -295,7 +295,7 @@ base::Value* V8ValueConverter::FromV8Array(
       val->CreationContext() != isolate->GetCurrentContext())
     scope.reset(new v8::Context::Scope(val->CreationContext()));
 
-  base::ListValue* result = new base::ListValue();
+  auto* result = new base::ListValue();
 
   // Only fields with integer keys are carried over to the ListValue.
   for (uint32_t i = 0; i < val->Length(); ++i) {
diff --git a/atom/common/node_bindings_mac.cc b/atom/common/node_bindings_mac.cc
index 9e61d27f496..cbcbdba3605 100644
--- a/atom/common/node_bindings_mac.cc
+++ b/atom/common/node_bindings_mac.cc
@@ -54,7 +54,8 @@ void NodeBindingsMac::PollEvents() {
   // Wait for new libuv events.
   int r;
   do {
-    r = select(fd + 1, &readset, NULL, NULL, timeout == -1 ? NULL : &tv);
+    r = select(fd + 1, &readset, nullptr, nullptr,
+               timeout == -1 ? nullptr : &tv);
   } while (r == -1 && errno == EINTR);
 }
 
diff --git a/atom/renderer/api/atom_api_renderer_ipc.cc b/atom/renderer/api/atom_api_renderer_ipc.cc
index a82562f9361..49f917292bb 100644
--- a/atom/renderer/api/atom_api_renderer_ipc.cc
+++ b/atom/renderer/api/atom_api_renderer_ipc.cc
@@ -20,11 +20,11 @@ namespace {
 RenderView* GetCurrentRenderView() {
   WebLocalFrame* frame = WebLocalFrame::frameForCurrentContext();
   if (!frame)
-    return NULL;
+    return nullptr;
 
   WebView* view = frame->view();
   if (!view)
-    return NULL;  // can happen during closing.
+    return nullptr;  // can happen during closing.
 
   return RenderView::FromWebView(view);
 }
@@ -33,7 +33,7 @@ void Send(mate::Arguments* args,
           const base::string16& channel,
           const base::ListValue& arguments) {
   RenderView* render_view = GetCurrentRenderView();
-  if (render_view == NULL)
+  if (render_view == nullptr)
     return;
 
   bool success = render_view->Send(new AtomViewHostMsg_Message(
@@ -49,7 +49,7 @@ base::string16 SendSync(mate::Arguments* args,
   base::string16 json;
 
   RenderView* render_view = GetCurrentRenderView();
-  if (render_view == NULL)
+  if (render_view == nullptr)
     return json;
 
   IPC::SyncMessage* message = new AtomViewHostMsg_Message_Sync(
diff --git a/atom/renderer/api/atom_api_web_frame.cc b/atom/renderer/api/atom_api_web_frame.cc
index 0b291d3b552..dce72b58095 100644
--- a/atom/renderer/api/atom_api_web_frame.cc
+++ b/atom/renderer/api/atom_api_web_frame.cc
@@ -39,7 +39,7 @@ class ScriptExecutionCallback : public blink::WebScriptExecutionCallback {
 
   explicit ScriptExecutionCallback(const CompletionCallback& callback)
       : callback_(callback) {}
-  ~ScriptExecutionCallback() {}
+  ~ScriptExecutionCallback() override {}
 
   void completed(
       const blink::WebVector<v8::Local<v8::Value>>& result) override {
diff --git a/atom/renderer/atom_render_view_observer.cc b/atom/renderer/atom_render_view_observer.cc
index 7ee93efb39b..45a41eef8ac 100644
--- a/atom/renderer/atom_render_view_observer.cc
+++ b/atom/renderer/atom_render_view_observer.cc
@@ -132,10 +132,10 @@ void AtomRenderViewObserver::DraggableRegionsChanged(blink::WebFrame* frame) {
   blink::WebVector<blink::WebDraggableRegion> webregions =
       frame->document().draggableRegions();
   std::vector<DraggableRegion> regions;
-  for (size_t i = 0; i < webregions.size(); ++i) {
+  for (const auto& webregion : webregions) {
     DraggableRegion region;
-    region.bounds = webregions[i].bounds;
-    region.draggable = webregions[i].draggable;
+    region.bounds = webregion.bounds;
+    region.draggable = webregion.draggable;
     regions.push_back(region);
   }
   Send(new AtomViewHostMsg_UpdateDraggableRegions(routing_id(), regions));
diff --git a/atom/utility/atom_content_utility_client.cc b/atom/utility/atom_content_utility_client.cc
index aff567fbcaa..8d4ccf62893 100644
--- a/atom/utility/atom_content_utility_client.cc
+++ b/atom/utility/atom_content_utility_client.cc
@@ -58,8 +58,7 @@ bool AtomContentUtilityClient::OnMessageReceived(
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
-  for (Handlers::iterator it = handlers_.begin();
-       !handled && it != handlers_.end(); ++it) {
+  for (auto it = handlers_.begin(); !handled && it != handlers_.end(); ++it) {
     handled = (*it)->OnMessageReceived(message);
   }