diff --git a/example/plugins/c-api/ssl_preaccept/ssl_preaccept.cc b/example/plugins/c-api/ssl_preaccept/ssl_preaccept.cc
index d5805844f14..be662ad29b1 100644
--- a/example/plugins/c-api/ssl_preaccept/ssl_preaccept.cc
+++ b/example/plugins/c-api/ssl_preaccept/ssl_preaccept.cc
@@ -39,7 +39,7 @@
 
 namespace
 {
-typedef std::pair<IpAddr, IpAddr> IpRange;
+using IpRange      = std::pair<IpAddr, IpAddr>;
 using IpRangeQueue = std::deque<IpRange>;
 IpRangeQueue ClientBlindTunnelIp;
 
diff --git a/iocore/cache/test/main.cc b/iocore/cache/test/main.cc
index 7c57a0cc638..3585ab68bea 100644
--- a/iocore/cache/test/main.cc
+++ b/iocore/cache/test/main.cc
@@ -210,7 +210,7 @@ CacheWriteTest::start_test(int event, void *e)
   }
 
   SET_HANDLER(&CacheWriteTest::write_event);
-  cacheProcessor.open_write(this, 0, &key, (CacheHTTPHdr *)this->info.request_get(), old_info);
+  cacheProcessor.open_write(this, 0, &key, static_cast<CacheHTTPHdr *>(this->info.request_get()), old_info);
   return 0;
 }
 
@@ -271,7 +271,7 @@ CacheReadTest::start_test(int event, void *e)
   key = generate_key(this->info);
 
   SET_HANDLER(&CacheReadTest::read_event);
-  cacheProcessor.open_read(this, &key, (CacheHTTPHdr *)this->info.request_get(), &this->params);
+  cacheProcessor.open_read(this, &key, static_cast<CacheHTTPHdr *>(this->info.request_get()), &this->params);
   return 0;
 }
 
diff --git a/plugins/background_fetch/background_fetch.cc b/plugins/background_fetch/background_fetch.cc
index cc5c7fd3e1f..ba6837265e2 100644
--- a/plugins/background_fetch/background_fetch.cc
+++ b/plugins/background_fetch/background_fetch.cc
@@ -55,7 +55,7 @@ static const std::array<const std::string_view, 6> FILTER_HEADERS{
 // Hold the global background fetch state. This is currently shared across all
 // configurations, as a singleton. ToDo: Would it ever make sense to do this
 // per remap rule? Maybe for per-remap logging ??
-typedef std::unordered_map<std::string, bool> OutstandingRequests;
+using OutstandingRequests = std::unordered_map<std::string, bool>;
 
 class BgFetchState
 {
diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index 5b43d45fc16..cb294e8058c 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -42,10 +42,10 @@
 
 namespace
 {
-typedef enum parent_select_mode {
+using parent_select_mode_t = enum parent_select_mode {
   PS_DEFAULT,      // Default ATS parent selection mode
   PS_CACHEKEY_URL, // Set parent selection url to cache_key url
-} parent_select_mode_t;
+};
 
 struct pluginconfig {
   parent_select_mode_t ps_mode{PS_DEFAULT};
diff --git a/plugins/escalate/escalate.cc b/plugins/escalate/escalate.cc
index 32663bdb447..71bc3944b7b 100644
--- a/plugins/escalate/escalate.cc
+++ b/plugins/escalate/escalate.cc
@@ -49,7 +49,7 @@ struct EscalationState {
     std::string target;
   };
 
-  typedef std::map<unsigned, RetryInfo> StatusMapType;
+  using StatusMapType = std::map<unsigned int, RetryInfo>;
 
   EscalationState()
   {
diff --git a/plugins/esi/esi.cc b/plugins/esi/esi.cc
index b92da0c5224..9d223b5f997 100644
--- a/plugins/esi/esi.cc
+++ b/plugins/esi/esi.cc
@@ -609,7 +609,7 @@ cacheNodeList(ContData *cont_data)
   string body("");
   cont_data->esi_proc->packNodeList(body, false);
   char buf[64];
-  snprintf(buf, 64, "%s: %d\r\n\r\n", TS_MIME_FIELD_CONTENT_LENGTH, (int)body.size());
+  snprintf(buf, 64, "%s: %d\r\n\r\n", TS_MIME_FIELD_CONTENT_LENGTH, static_cast<int>(body.size()));
 
   post_request.append(buf);
   post_request.append(body);
diff --git a/plugins/esi/test/parser_test.cc b/plugins/esi/test/parser_test.cc
index c200eeb2cb3..f2b3873f3c9 100644
--- a/plugins/esi/test/parser_test.cc
+++ b/plugins/esi/test/parser_test.cc
@@ -115,7 +115,7 @@ main()
   {
     cout << endl << "==================== Test 6: Invalid Quoted URL test " << endl;
     EsiParser parser("parser_test", &Debug, &Error);
-    string input_data = "<esi:include src=abc\"\"de\"f />";
+    string input_data = R"(<esi:include src=abc""de"f />)";
 
     DocNodeList node_list;
     assert(parser.parseChunk(input_data, node_list) == false);
diff --git a/plugins/esi/test/utils_test.cc b/plugins/esi/test/utils_test.cc
index 9c1e059d875..924ff936dc4 100644
--- a/plugins/esi/test/utils_test.cc
+++ b/plugins/esi/test/utils_test.cc
@@ -75,7 +75,7 @@ main()
   const char *expected_strs4[] = {"pos", " SKY BAR ", "spaceid", "12123", nullptr};
   checkAttributes("test4", attr_list, expected_strs4);
 
-  string str5("a=\"b & xyz\"&c=d&e=f&g=h\"");
+  string str5(R"(a="b & xyz"&c=d&e=f&g=h")");
   Utils::parseAttributes(str5, attr_list, "&");
   const char *expected_strs5[] = {"a", "b & xyz", "c", "d", "e", "f", nullptr};
   checkAttributes("test5", attr_list, expected_strs5);
@@ -91,9 +91,9 @@ main()
   checkAttributes("test7", attr_list, expected_strs7);
 
   const char *escaped_sequence = R"({\"site-attribute\":\"content=no_expandable; ajax_cert_expandable\"})";
-  string str8("pos=\"FPM1\" spaceid=96584352 extra_mime=\"");
+  string str8(R"(pos="FPM1" spaceid=96584352 extra_mime=")");
   str8.append(escaped_sequence);
-  str8.append("\" foo=bar a=\"b\"");
+  str8.append(R"(" foo=bar a="b")");
   const char *expected_strs8[] = {"pos", "FPM1", "spaceid", "96584352", "extra_mime", escaped_sequence,
                                   "foo", "bar",  "a",       "b",        nullptr};
   Utils::parseAttributes(str8, attr_list);
diff --git a/plugins/experimental/access_control/utils.cc b/plugins/experimental/access_control/utils.cc
index cd212d11506..53911e463b3 100644
--- a/plugins/experimental/access_control/utils.cc
+++ b/plugins/experimental/access_control/utils.cc
@@ -240,7 +240,7 @@ cryptoMessageDigestGet(const char *digestType, const char *data, size_t dataLen,
 #else
   ctx = HMAC_CTX_new();
 #endif
-  if (!HMAC_Init_ex(ctx, key, keyLen, md, NULL)) {
+  if (!HMAC_Init_ex(ctx, key, keyLen, md, nullptr)) {
     AccessControlError("failed to create EVP message digest context: %s", cryptoErrStr(buffer, sizeof(buffer)));
     goto err;
   }
diff --git a/plugins/experimental/cache_fill/background_fetch.cc b/plugins/experimental/cache_fill/background_fetch.cc
index ba749074102..2b4a655dad1 100644
--- a/plugins/experimental/cache_fill/background_fetch.cc
+++ b/plugins/experimental/cache_fill/background_fetch.cc
@@ -38,7 +38,7 @@
 #include "ts/ts.h"
 #include "ts/remap.h"
 #include "background_fetch.h"
-typedef std::unordered_map<std::string, bool> OutstandingRequests;
+using OutstandingRequests = std::unordered_map<std::string, bool>;
 
 ///////////////////////////////////////////////////////////////////////////
 // Set a header to a specific value. This will avoid going to through a
diff --git a/plugins/experimental/cache_fill/cache_fill.cc b/plugins/experimental/cache_fill/cache_fill.cc
index 0165e5f1fe5..17b8607381e 100644
--- a/plugins/experimental/cache_fill/cache_fill.cc
+++ b/plugins/experimental/cache_fill/cache_fill.cc
@@ -68,11 +68,12 @@ getCacheLookupResultName(TSCacheLookupResult result)
 static bool
 cont_check_cacheable(TSHttpTxn txnp)
 {
-  if (TSHttpTxnIsInternal(txnp))
+  if (TSHttpTxnIsInternal(txnp)) {
     return false;
+  }
   int lookupStatus;
   TSHttpTxnCacheLookupStatusGet(txnp, &lookupStatus);
-  TSDebug(PLUGIN_NAME, "lookup status: %s", getCacheLookupResultName((TSCacheLookupResult)lookupStatus));
+  TSDebug(PLUGIN_NAME, "lookup status: %s", getCacheLookupResultName(static_cast<TSCacheLookupResult>(lookupStatus)));
   bool ret = false;
   if (TS_CACHE_LOOKUP_MISS == lookupStatus || TS_CACHE_LOOKUP_HIT_STALE == lookupStatus) {
     bool const nostore = TSHttpTxnServerRespNoStoreGet(txnp);
diff --git a/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc b/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc
index 9033f4e9e2d..b5063e90ad8 100644
--- a/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc
+++ b/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc
@@ -75,11 +75,11 @@ static int OPEN_WRITE_FAIL_REQ_DELAY_TIMEOUT     = 500;
 
 static bool global_init = false;
 
-typedef struct _RequestData {
+using RequestData = struct _RequestData {
   TSHttpTxn txnp;
   int wl_retry; // write lock failure retry count
   std::string req_url;
-} RequestData;
+};
 
 static int
 add_redirect_header(TSMBuffer &bufp, TSMLoc &hdr_loc, const std::string &location)
diff --git a/plugins/experimental/cookie_remap/cookie_remap.cc b/plugins/experimental/cookie_remap/cookie_remap.cc
index 5515497ca00..ceef473d55f 100644
--- a/plugins/experimental/cookie_remap/cookie_remap.cc
+++ b/plugins/experimental/cookie_remap/cookie_remap.cc
@@ -811,8 +811,8 @@ class op
   TSHttpStatus else_status = TS_HTTP_STATUS_NONE;
 };
 
-typedef std::pair<std::string, std::string> StringPair;
-using OpMap = std::vector<StringPair>;
+using StringPair = std::pair<std::string, std::string>;
+using OpMap      = std::vector<StringPair>;
 
 //----------------------------------------------------------------------------
 static bool
diff --git a/plugins/experimental/magick/magick.cc b/plugins/experimental/magick/magick.cc
index d320d017045..24cd0f584c8 100644
--- a/plugins/experimental/magick/magick.cc
+++ b/plugins/experimental/magick/magick.cc
@@ -479,7 +479,7 @@ struct ImageTransform : TransformationPlugin {
   {
     TSDebug(PLUGIN_TAG, "handleInputComplete");
 
-    threadPool_.emplace_back([this](void) {
+    threadPool_.emplace_back([this]() {
       magick::Image image;
       magick::Exception exception;
       magick::Wand wand;
diff --git a/plugins/experimental/maxmind_acl/mmdb.cc b/plugins/experimental/maxmind_acl/mmdb.cc
index 95ab3b0b4fa..7c1d7c3c055 100644
--- a/plugins/experimental/maxmind_acl/mmdb.cc
+++ b/plugins/experimental/maxmind_acl/mmdb.cc
@@ -150,8 +150,8 @@ Acl::loaddeny(const YAML::Node &denyNode)
       YAML::Node country = denyNode["country"];
       if (!country.IsNull()) {
         if (country.IsSequence()) {
-          for (std::size_t i = 0; i < country.size(); i++) {
-            allow_country.insert_or_assign(country[i].as<std::string>(), false);
+          for (auto &&i : country) {
+            allow_country.insert_or_assign(i.as<std::string>(), false);
           }
         } else {
           TSDebug(PLUGIN_NAME, "Invalid country code allow list yaml");
@@ -170,9 +170,9 @@ Acl::loaddeny(const YAML::Node &denyNode)
       if (!ip.IsNull()) {
         if (ip.IsSequence()) {
           // Do IP Deny processing
-          for (std::size_t i = 0; i < ip.size(); i++) {
+          for (auto &&i : ip) {
             IpAddr min, max;
-            ats_ip_range_parse(std::string_view{ip[i].as<std::string>()}, min, max);
+            ats_ip_range_parse(std::string_view{i.as<std::string>()}, min, max);
             deny_ip_map.fill(min, max, nullptr);
             TSDebug(PLUGIN_NAME, "loading ip: valid: %d, fam %d ", min.isValid(), min.family());
           }
@@ -230,8 +230,8 @@ Acl::loadallow(const YAML::Node &allowNode)
       YAML::Node country = allowNode["country"];
       if (!country.IsNull()) {
         if (country.IsSequence()) {
-          for (std::size_t i = 0; i < country.size(); i++) {
-            allow_country.insert_or_assign(country[i].as<std::string>(), true);
+          for (auto &&i : country) {
+            allow_country.insert_or_assign(i.as<std::string>(), true);
           }
 
         } else {
@@ -251,9 +251,9 @@ Acl::loadallow(const YAML::Node &allowNode)
       if (!ip.IsNull()) {
         if (ip.IsSequence()) {
           // Do IP Allow processing
-          for (std::size_t i = 0; i < ip.size(); i++) {
+          for (auto &&i : ip) {
             IpAddr min, max;
-            ats_ip_range_parse(std::string_view{ip[i].as<std::string>()}, min, max);
+            ats_ip_range_parse(std::string_view{i.as<std::string>()}, min, max);
             allow_ip_map.fill(min, max, nullptr);
             TSDebug(PLUGIN_NAME, "loading ip: valid: %d, fam %d ", min.isValid(), min.family());
           }
@@ -290,9 +290,9 @@ Acl::parseregex(const YAML::Node &regex, bool allow)
     if (!regex.IsNull()) {
       if (regex.IsSequence()) {
         // Parse each country-regex pair
-        for (std::size_t i = 0; i < regex.size(); i++) {
+        for (const auto &i : regex) {
           plugin_regex temp;
-          auto temprule = regex[i].as<std::vector<std::string>>();
+          auto temprule = i.as<std::vector<std::string>>();
           temp._regex_s = temprule.back();
           const char *error;
           int erroffset;
@@ -311,11 +311,11 @@ Acl::parseregex(const YAML::Node &regex, bool allow)
           }
 
           for (std::size_t y = 0; y < temprule.size() - 1; y++) {
-            TSDebug(PLUGIN_NAME, "Adding regex: %s, for country: %s", temp._regex_s.c_str(), regex[i][y].as<std::string>().c_str());
+            TSDebug(PLUGIN_NAME, "Adding regex: %s, for country: %s", temp._regex_s.c_str(), i[y].as<std::string>().c_str());
             if (allow) {
-              allow_regex[regex[i][y].as<std::string>()].push_back(temp);
+              allow_regex[i[y].as<std::string>()].push_back(temp);
             } else {
-              deny_regex[regex[i][y].as<std::string>()].push_back(temp);
+              deny_regex[i[y].as<std::string>()].push_back(temp);
             }
           }
         }
@@ -423,7 +423,7 @@ Acl::eval(TSRemapRequestInfo *rri, TSHttpTxn txnp)
       return ret;
     }
 
-    if (NULL != entry_data_list) {
+    if (nullptr != entry_data_list) {
       // This is useful to be able to dump out a full record of a
       // mmdb entry for debug. Enabling can help if you want to figure
       // out how to add new fields
@@ -481,7 +481,7 @@ Acl::eval(TSRemapRequestInfo *rri, TSHttpTxn txnp)
     break;
   }
 
-  if (NULL != entry_data_list) {
+  if (nullptr != entry_data_list) {
     MMDB_free_entry_data_list(entry_data_list);
   }
 
@@ -498,7 +498,7 @@ Acl::eval_country(MMDB_entry_data_s *entry_data, const char *path, int path_len)
   bool ret     = false;
   bool allow   = default_allow;
   char *output = nullptr;
-  output       = (char *)malloc((sizeof(char) * entry_data->data_size));
+  output       = static_cast<char *>(malloc((sizeof(char) * entry_data->data_size)));
   strncpy(output, entry_data->utf8_string, entry_data->data_size);
   TSDebug(PLUGIN_NAME, "This IP Country Code: %s", output);
   auto exists = allow_country.count(output);
diff --git a/plugins/experimental/memcache/tsmemcache.cc b/plugins/experimental/memcache/tsmemcache.cc
index 532c2bb4b31..4440670d836 100644
--- a/plugins/experimental/memcache/tsmemcache.cc
+++ b/plugins/experimental/memcache/tsmemcache.cc
@@ -132,7 +132,7 @@ MCAccept::main_event(int event, void *data)
     }
     return EVENT_CONT;
   } else {
-    Fatal("tsmemcache accept received fatal error: errno = %d", -((int)(intptr_t)data));
+    Fatal("tsmemcache accept received fatal error: errno = %d", -(static_cast<int>((intptr_t)data)));
     return EVENT_CONT;
   }
 }
diff --git a/plugins/experimental/mysql_remap/mysql_remap.cc b/plugins/experimental/mysql_remap/mysql_remap.cc
index f2c69b26486..2d1551af6e1 100644
--- a/plugins/experimental/mysql_remap/mysql_remap.cc
+++ b/plugins/experimental/mysql_remap/mysql_remap.cc
@@ -28,9 +28,9 @@
 
 MYSQL mysql;
 
-typedef struct {
+using my_data = struct {
   char *query;
-} my_data;
+};
 
 bool
 do_mysql_remap(TSCont contp, TSHttpTxn txnp)
diff --git a/plugins/experimental/rate_limit/rate_limit.cc b/plugins/experimental/rate_limit/rate_limit.cc
index c05a4862225..1d0d669cbb5 100644
--- a/plugins/experimental/rate_limit/rate_limit.cc
+++ b/plugins/experimental/rate_limit/rate_limit.cc
@@ -17,7 +17,7 @@
  */
 #include <unistd.h>
 #include <getopt.h>
-#include <stdlib.h>
+#include <cstdlib>
 #include <ts/ts.h>
 #include <ts/remap.h>
 
diff --git a/plugins/experimental/statichit/statichit.cc b/plugins/experimental/statichit/statichit.cc
index c20fb364013..4c5c6d4f902 100644
--- a/plugins/experimental/statichit/statichit.cc
+++ b/plugins/experimental/statichit/statichit.cc
@@ -522,7 +522,7 @@ StaticHitTxnHook(TSCont contp, TSEvent event, void *edata)
     }
 
     method = TSHttpHdrMethodGet(bufp, hdr_loc, &method_length);
-    if (NULL == method) {
+    if (nullptr == method) {
       VERROR("Couldn't retrieve client request method");
       goto done;
     }
@@ -601,9 +601,9 @@ TSReturnCode
 TSRemapNewInstance(int argc, char *argv[], void **ih, char * /* errbuf ATS_UNUSED */, int /* errbuf_size ATS_UNUSED */)
 {
   static const struct option longopt[] = {
-    {"file-path", required_argument, NULL, 'f'},    {"mime-type", required_argument, NULL, 'm'},
-    {"max-age", required_argument, NULL, 'a'},      {"failure-code", required_argument, NULL, 'c'},
-    {"success-code", required_argument, NULL, 's'}, {NULL, no_argument, NULL, '\0'}};
+    {"file-path", required_argument, nullptr, 'f'},    {"mime-type", required_argument, nullptr, 'm'},
+    {"max-age", required_argument, nullptr, 'a'},      {"failure-code", required_argument, nullptr, 'c'},
+    {"success-code", required_argument, nullptr, 's'}, {nullptr, no_argument, nullptr, '\0'}};
 
   std::string filePath;
   std::string mimeType = "text/plain";
@@ -616,7 +616,7 @@ TSRemapNewInstance(int argc, char *argv[], void **ih, char * /* errbuf ATS_UNUSE
   optind = 0;
 
   while (true) {
-    int opt = getopt_long(argc, (char *const *)argv, "f:m:a:c:s:", longopt, NULL);
+    int opt = getopt_long(argc, (char *const *)argv, "f:m:a:c:s:", longopt, nullptr);
 
     switch (opt) {
     case 'f': {
@@ -646,7 +646,7 @@ TSRemapNewInstance(int argc, char *argv[], void **ih, char * /* errbuf ATS_UNUSE
     return TS_ERROR;
   }
 
-  if (filePath.find("/") != 0) {
+  if (filePath.find('/') != 0) {
     filePath = std::string(TSConfigDirGet()) + '/' + filePath;
   }
 
diff --git a/plugins/experimental/stream_editor/stream_editor.cc b/plugins/experimental/stream_editor/stream_editor.cc
index 0bd7d8a8839..e6e524e95cc 100644
--- a/plugins/experimental/stream_editor/stream_editor.cc
+++ b/plugins/experimental/stream_editor/stream_editor.cc
@@ -551,7 +551,7 @@ class rule_t
 using ruleset_t = std::vector<rule_t>;
 using rule_p    = ruleset_t::const_iterator;
 
-typedef struct contdata_t {
+using contdata_t = struct contdata_t {
   TSCont cont             = nullptr;
   TSIOBuffer out_buf      = nullptr;
   TSIOBufferReader out_rd = nullptr;
@@ -582,7 +582,7 @@ typedef struct contdata_t {
       contbuf_sz = 2 * sz - 1;
     }
   }
-} contdata_t;
+};
 
 static int64_t
 process_block(contdata_t *contdata, TSIOBufferReader reader)
diff --git a/plugins/header_rewrite/conditions_geo_maxmind.cc b/plugins/header_rewrite/conditions_geo_maxmind.cc
index 5e0e76c5d20..27912db1de2 100644
--- a/plugins/header_rewrite/conditions_geo_maxmind.cc
+++ b/plugins/header_rewrite/conditions_geo_maxmind.cc
@@ -114,7 +114,7 @@ MMConditionGeo::get_geo_string(const sockaddr *addr) const
   }
   ret = std::string(entry_data.utf8_string, entry_data.data_size);
 
-  if (NULL != entry_data_list) {
+  if (nullptr != entry_data_list) {
     MMDB_free_entry_data_list(entry_data_list);
   }
 
@@ -176,7 +176,7 @@ MMConditionGeo::get_geo_int(const sockaddr *addr) const
   }
   ret = entry_data.uint32;
 
-  if (NULL != entry_data_list) {
+  if (nullptr != entry_data_list) {
     MMDB_free_entry_data_list(entry_data_list);
   }
 
diff --git a/plugins/header_rewrite/header_rewrite.cc b/plugins/header_rewrite/header_rewrite.cc
index 09593eacab4..221c550adea 100644
--- a/plugins/header_rewrite/header_rewrite.cc
+++ b/plugins/header_rewrite/header_rewrite.cc
@@ -302,7 +302,7 @@ cont_rewrite_headers(TSCont contp, TSEvent event, void *edata)
   return 0;
 }
 
-static const struct option longopt[] = {{"geo-db-path", required_argument, NULL, 'm'}, {NULL, no_argument, NULL, '\0'}};
+static const struct option longopt[] = {{"geo-db-path", required_argument, nullptr, 'm'}, {nullptr, no_argument, nullptr, '\0'}};
 
 ///////////////////////////////////////////////////////////////////////////////
 // Initialize the InkAPI plugin for the global hooks we support.
@@ -323,7 +323,7 @@ TSPluginInit(int argc, const char *argv[])
 
   std::string geoDBpath;
   while (true) {
-    int opt = getopt_long(argc, (char *const *)argv, "m:", longopt, NULL);
+    int opt = getopt_long(argc, const_cast<char *const *>(argv), "m:", longopt, nullptr);
 
     switch (opt) {
     case 'm': {
@@ -335,7 +335,7 @@ TSPluginInit(int argc, const char *argv[])
     }
   }
 
-  if (!geoDBpath.empty() && geoDBpath.find("/") != 0) {
+  if (!geoDBpath.empty() && geoDBpath.find('/') != 0) {
     geoDBpath = std::string(TSConfigDirGet()) + '/' + geoDBpath;
   }
 
@@ -421,7 +421,7 @@ TSRemapNewInstance(int argc, char *argv[], void **ih, char * /* errbuf ATS_UNUSE
 
   std::string geoDBpath;
   while (true) {
-    int opt = getopt_long(argc, (char *const *)argv, "m:", longopt, NULL);
+    int opt = getopt_long(argc, (char *const *)argv, "m:", longopt, nullptr);
 
     switch (opt) {
     case 'm': {
@@ -434,7 +434,7 @@ TSRemapNewInstance(int argc, char *argv[], void **ih, char * /* errbuf ATS_UNUSE
   }
 
   if (!geoDBpath.empty()) {
-    if (geoDBpath.find("/") != 0) {
+    if (geoDBpath.find('/') != 0) {
       geoDBpath = std::string(TSConfigDirGet()) + '/' + geoDBpath;
     }
 
diff --git a/plugins/multiplexer/ats-multiplexer.cc b/plugins/multiplexer/ats-multiplexer.cc
index 8a814d88758..e192c31a9c2 100644
--- a/plugins/multiplexer/ats-multiplexer.cc
+++ b/plugins/multiplexer/ats-multiplexer.cc
@@ -78,7 +78,7 @@ TSRemapNewInstance(int argc, char **argv, void **i, char *, int)
   instance->skipPostPut = false;
 
   if (argc > 2) {
-    std::copy_if(argv + 2, argv + argc, std::back_inserter(instance->origins), [&](std::string s) {
+    std::copy_if(argv + 2, argv + argc, std::back_inserter(instance->origins), [&](const std::string &s) {
       if (s == "proxy.config.multiplexer.skip_post_put=1") {
         instance->skipPostPut = true;
         return false;
diff --git a/proxy/CacheControl.cc b/proxy/CacheControl.cc
index 91749f181ac..f1ed4e2429f 100644
--- a/proxy/CacheControl.cc
+++ b/proxy/CacheControl.cc
@@ -59,7 +59,7 @@ static const char *CC_directive_str[CC_NUM_TYPES] = {
   // "CACHE_AUTH_CONTENT"
 };
 
-typedef ControlMatcher<CacheControlRecord, CacheControlResult> CC_table;
+using CC_table = ControlMatcher<CacheControlRecord, CacheControlResult>;
 
 // Global Ptrs
 static Ptr<ProxyMutex> reconfig_mutex;
diff --git a/proxy/ParentSelection.cc b/proxy/ParentSelection.cc
index 3d38dcd268c..5f9182160a5 100644
--- a/proxy/ParentSelection.cc
+++ b/proxy/ParentSelection.cc
@@ -35,7 +35,7 @@
 #define MAX_SIMPLE_RETRIES 5
 #define MAX_UNAVAILABLE_SERVER_RETRIES 5
 
-typedef ControlMatcher<ParentRecord, ParentResult> P_table;
+using P_table = ControlMatcher<ParentRecord, ParentResult>;
 
 // Global Vars for Parent Selection
 static const char modulePrefix[]                             = "[ParentSelection]";
diff --git a/proxy/hdrs/HuffmanCodec.cc b/proxy/hdrs/HuffmanCodec.cc
index 562fa36b88a..546269042c6 100644
--- a/proxy/hdrs/HuffmanCodec.cc
+++ b/proxy/hdrs/HuffmanCodec.cc
@@ -70,11 +70,11 @@ static const huffman_entry huffman_table[] = {
   {0x7ffffe8, 27}, {0x7ffffe9, 27},  {0x7ffffea, 27}, {0x7ffffeb, 27},  {0xffffffe, 28}, {0x7ffffec, 27}, {0x7ffffed, 27},
   {0x7ffffee, 27}, {0x7ffffef, 27},  {0x7fffff0, 27}, {0x3ffffee, 26},  {0x3fffffff, 30}};
 
-typedef struct node {
+using Node = struct node {
   node *left, *right;
   char ascii_code;
   bool leaf_node;
-} Node;
+};
 
 Node *HUFFMAN_TREE_ROOT;
 
diff --git a/proxy/http/HttpTransact.cc b/proxy/http/HttpTransact.cc
index d6aa87444eb..8e121af1946 100644
--- a/proxy/http/HttpTransact.cc
+++ b/proxy/http/HttpTransact.cc
@@ -7664,7 +7664,7 @@ HttpTransact::build_request(State *s, HTTPHdr *base_request, HTTPHdr *outgoing_r
 
   URL *url = outgoing_request->url_get();
   // Remove fragment from upstream URL
-  url->fragment_set(NULL, 0);
+  url->fragment_set(nullptr, 0);
 
   // Check whether a Host header field is missing from a 1.0 or 1.1 request.
   if (outgoing_version != HTTP_0_9 && !outgoing_request->presence(MIME_PRESENCE_HOST)) {
diff --git a/proxy/http2/HPACK.cc b/proxy/http2/HPACK.cc
index 09d1a531e9f..7a5c73d30cf 100644
--- a/proxy/http2/HPACK.cc
+++ b/proxy/http2/HPACK.cc
@@ -33,7 +33,7 @@ namespace
 // its value's length in octets, and 32.
 const static unsigned ADDITIONAL_OCTETS = 32;
 
-typedef enum {
+using TS_HPACK_STATIC_TABLE_ENTRY = enum {
   TS_HPACK_STATIC_TABLE_0 = 0,
   TS_HPACK_STATIC_TABLE_AUTHORITY,
   TS_HPACK_STATIC_TABLE_METHOD_GET,
@@ -97,7 +97,7 @@ typedef enum {
   TS_HPACK_STATIC_TABLE_VIA,
   TS_HPACK_STATIC_TABLE_WWW_AUTHENTICATE,
   TS_HPACK_STATIC_TABLE_ENTRY_NUM
-} TS_HPACK_STATIC_TABLE_ENTRY;
+};
 
 constexpr HpackHeaderField STATIC_TABLE[] = {{"", ""},
                                              {":authority", ""},
diff --git a/proxy/logging/LogField.cc b/proxy/logging/LogField.cc
index c884cc296d1..34d23dd187f 100644
--- a/proxy/logging/LogField.cc
+++ b/proxy/logging/LogField.cc
@@ -171,7 +171,7 @@ struct cmp_str {
 };
 } // namespace
 
-typedef std::map<ts::ConstBuffer, TSMilestonesType, cmp_str> milestone_map;
+using milestone_map = std::map<ts::ConstBuffer, TSMilestonesType, cmp_str>;
 static milestone_map m_milestone_map;
 
 struct milestone {
diff --git a/src/traffic_crashlog/traffic_crashlog.cc b/src/traffic_crashlog/traffic_crashlog.cc
index de954ecf418..936ccefda75 100644
--- a/src/traffic_crashlog/traffic_crashlog.cc
+++ b/src/traffic_crashlog/traffic_crashlog.cc
@@ -192,8 +192,8 @@ main(int /* argc ATS_UNUSED */, const char **argv)
     diags->config.outputs[DL_Emergency].to_syslog = true;
   }
 
-  Note("crashlog started, target=%ld, debug=%s syslog=%s, uid=%ld euid=%ld", (long)target_pid, debug_mode ? "true" : "false",
-       syslog_mode ? "true" : "false", (long)getuid(), (long)geteuid());
+  Note("crashlog started, target=%ld, debug=%s syslog=%s, uid=%ld euid=%ld", static_cast<long>(target_pid),
+       debug_mode ? "true" : "false", syslog_mode ? "true" : "false", (long)getuid(), (long)geteuid());
 
   mgmterr = TSInit(nullptr, (TSInitOptionT)(TS_MGMT_OPT_NO_EVENTS | TS_MGMT_OPT_NO_SOCK_TESTS));
   if (mgmterr != TS_ERR_OKAY) {
diff --git a/src/traffic_ctl/config.cc b/src/traffic_ctl/config.cc
index d60cb3a07d0..e3433392310 100644
--- a/src/traffic_ctl/config.cc
+++ b/src/traffic_ctl/config.cc
@@ -369,8 +369,8 @@ CtrlEngine::config_status()
   CTRL_MGMT_CHECK(manager.fetch("proxy.node.config.restart_required.manager"));
 
   std::cout << CtrlMgmtRecordValue(version).c_str() << std::endl;
-  std::cout << "Started at " << timestr((time_t)starttime.as_int()).c_str();
-  std::cout << "Last reconfiguration at " << timestr((time_t)configtime.as_int()).c_str();
+  std::cout << "Started at " << timestr(static_cast<time_t>(starttime.as_int())).c_str();
+  std::cout << "Last reconfiguration at " << timestr(static_cast<time_t>(configtime.as_int())).c_str();
   std::cout << (reconfig.as_int() ? "Reconfiguration required" : "Configuration is current") << std::endl;
 
   if (proxy.as_int()) {
diff --git a/src/traffic_logstats/logstats.cc b/src/traffic_logstats/logstats.cc
index c581e1f223a..ae75bac1121 100644
--- a/src/traffic_logstats/logstats.cc
+++ b/src/traffic_logstats/logstats.cc
@@ -389,9 +389,9 @@ class UrlLru
       _dump_url(u, as_object);
     }
     if (as_object) {
-      std::cout << "  \"_timestamp\" : \"" << static_cast<int>(ink_time_wall_seconds()) << "\"" << std::endl;
+      std::cout << R"(  "_timestamp" : ")" << static_cast<int>(ink_time_wall_seconds()) << "\"" << std::endl;
     } else {
-      std::cout << "  { \"_timestamp\" : \"" << static_cast<int>(ink_time_wall_seconds()) << "\" }" << std::endl;
+      std::cout << R"(  { "_timestamp" : ")" << static_cast<int>(ink_time_wall_seconds()) << "\" }" << std::endl;
     }
   }
 
@@ -1929,8 +1929,8 @@ format_elapsed_line(const char *desc, const ElapsedStats &stat, bool json, bool
   if (json) {
     std::cout << "    " << '"' << desc << "\" : "
               << "{ ";
-    std::cout << "\"min\": \"" << stat.min << "\", ";
-    std::cout << "\"max\": \"" << stat.max << "\"";
+    std::cout << R"("min": ")" << stat.min << "\", ";
+    std::cout << R"("max": ")" << stat.max << "\"";
     if (!concise) {
       std::cout << ", \"avg\": \"" << std::setiosflags(ios::fixed) << std::setprecision(2) << stat.avg << "\", ";
       std::cout << "\"dev\": \"" << std::setiosflags(ios::fixed) << std::setprecision(2) << stat.stddev << "\"";
@@ -1968,12 +1968,12 @@ format_line(const char *desc, const StatsCounter &stat, const StatsCounter &tota
   if (json) {
     std::cout << "    " << '"' << desc << "\" : "
               << "{ ";
-    std::cout << "\"req\": \"" << stat.count << "\", ";
+    std::cout << R"("req": ")" << stat.count << "\", ";
     if (!concise) {
       std::cout << "\"req_pct\": \"" << std::setiosflags(ios::fixed) << std::setprecision(2)
                 << (double)stat.count / total.count * 100 << "\", ";
     }
-    std::cout << "\"bytes\": \"" << stat.bytes << "\"";
+    std::cout << R"("bytes": ")" << stat.bytes << "\"";
 
     if (!concise) {
       std::cout << ", \"bytes_pct\": \"" << std::setiosflags(ios::fixed) << std::setprecision(2)
@@ -2260,7 +2260,7 @@ print_detail_stats(const OriginStats *stat, bool json, bool concise)
     std::cout << std::endl;
     std::cout << std::setw(cl.line_len) << std::setfill('_') << '_' << std::setfill(' ') << std::endl;
   } else {
-    std::cout << "    \"_timestamp\" : \"" << static_cast<int>(ink_time_wall_seconds()) << '"' << std::endl;
+    std::cout << R"(    "_timestamp" : ")" << static_cast<int>(ink_time_wall_seconds()) << '"' << std::endl;
   }
 }
 
diff --git a/src/traffic_server/Crash.cc b/src/traffic_server/Crash.cc
index d91f3fbbc06..fa3195880c9 100644
--- a/src/traffic_server/Crash.cc
+++ b/src/traffic_server/Crash.cc
@@ -158,7 +158,7 @@ crash_logger_invoke(int signo, siginfo_t *info, void *ctx)
     // ucontext_t can contain pointers, so it's highly platform dependent. On Linux with glibc, however, it is
     // a single memory block that we can just puke out.
     ATS_UNUSED_RETURN(write(crash_logger_fd, info, sizeof(siginfo_t)));
-    ATS_UNUSED_RETURN(write(crash_logger_fd, (ucontext_t *)ctx, sizeof(ucontext_t)));
+    ATS_UNUSED_RETURN(write(crash_logger_fd, static_cast<ucontext_t *>(ctx), sizeof(ucontext_t)));
 #endif
 
     close(crash_logger_fd);
diff --git a/src/traffic_server/InkAPI.cc b/src/traffic_server/InkAPI.cc
index 21495c1dbe3..6a26a0eeed3 100644
--- a/src/traffic_server/InkAPI.cc
+++ b/src/traffic_server/InkAPI.cc
@@ -7910,7 +7910,7 @@ char *
 TSMatcherReadIntoBuffer(char *file_name, int *file_len)
 {
   sdk_assert(sdk_sanity_check_null_ptr((void *)file_name) == TS_SUCCESS);
-  return readIntoBuffer((char *)file_name, "TSMatcher", file_len);
+  return readIntoBuffer(file_name, "TSMatcher", file_len);
 }
 
 char *
diff --git a/src/traffic_server/InkAPITest.cc b/src/traffic_server/InkAPITest.cc
index 3405755723c..6f345159d02 100644
--- a/src/traffic_server/InkAPITest.cc
+++ b/src/traffic_server/InkAPITest.cc
@@ -3380,7 +3380,7 @@ checkHttpTxnServerRespGet(SocketTest *test, void *data)
 static int
 checkHttpTxnServerSsnTransactionCount(SocketTest *test, void *data)
 {
-  TSHttpTxn txnp = (TSHttpTxn)data;
+  TSHttpTxn txnp = static_cast<TSHttpTxn>(data);
 
   int count = TSHttpTxnServerSsnTransactionCount(txnp);
   if (count < 0) {
diff --git a/src/traffic_server/SocksProxy.cc b/src/traffic_server/SocksProxy.cc
index c1f44c25559..62799a04557 100644
--- a/src/traffic_server/SocksProxy.cc
+++ b/src/traffic_server/SocksProxy.cc
@@ -149,7 +149,7 @@ SocksProxy::init(NetVConnection *netVC)
 
   SCOPED_MUTEX_LOCK(lock, mutex, this_ethread());
 
-  SET_HANDLER((EventHandler)&SocksProxy::acceptEvent);
+  SET_HANDLER(static_cast<EventHandler>(&SocksProxy::acceptEvent));
 
   handleEvent(NET_EVENT_ACCEPT, netVC);
 }
@@ -178,7 +178,7 @@ SocksProxy::acceptEvent(int event, void *data)
 
   buf->reset();
 
-  SET_HANDLER((EventHandler)&SocksProxy::mainEvent);
+  SET_HANDLER(static_cast<EventHandler>(&SocksProxy::mainEvent));
   vc_handler = &SocksProxy::state_read_client_request;
 
   timeout   = this_ethread()->schedule_in(this, HRTIME_SECONDS(netProcessor.socks_conf_stuff->socks_timeout));
@@ -299,7 +299,7 @@ SocksProxy::state_read_client_request(int event, void *data)
 
   unsigned char *p = (unsigned char *)reader->start();
 
-  Debug("SocksProxy", "Accepted connection from a version %d client", (int)p[0]);
+  Debug("SocksProxy", "Accepted connection from a version %d client", static_cast<int>(p[0]));
 
   switch (p[0]) {
   case SOCKS4_VERSION:
@@ -313,7 +313,7 @@ SocksProxy::state_read_client_request(int event, void *data)
     return (this->*vc_handler)(event, data);
     break;
   default:
-    Warning("Wrong version for Socks: %d\n", (int)p[0]);
+    Warning("Wrong version for Socks: %d\n", static_cast<int>(p[0]));
     state = SOCKS_ERROR;
     break;
   }
@@ -470,7 +470,7 @@ SocksProxy::state_read_socks5_client_request(int event, void *data)
   default:
     req_len = INT_MAX;
     state   = SOCKS_ERROR;
-    Debug("SocksProxy", "Illegal address type(%d)", (int)p[3]);
+    Debug("SocksProxy", "Illegal address type(%d)", static_cast<int>(p[3]));
   }
 
   if (state == SOCKS_ERROR) {
diff --git a/src/tscore/ink_file.cc b/src/tscore/ink_file.cc
index bd09666095f..6f054e7dbc1 100644
--- a/src/tscore/ink_file.cc
+++ b/src/tscore/ink_file.cc
@@ -56,11 +56,11 @@
 #include <linux/fs.h> /* for BLKGETSIZE.  sys/mount.h is another candidate */
 #endif
 
-typedef union {
+using ioctl_arg_t = union {
   uint64_t u64;
   uint32_t u32;
   off_t off;
-} ioctl_arg_t;
+};
 
 int
 ink_fputln(FILE *stream, const char *s)
diff --git a/src/tscore/ink_queue.cc b/src/tscore/ink_queue.cc
index f4a2841c06f..7a528e2d58c 100644
--- a/src/tscore/ink_queue.cc
+++ b/src/tscore/ink_queue.cc
@@ -74,10 +74,10 @@ struct ink_freelist_ops {
   void (*fl_bulkfree)(InkFreeList *, void *, void *, size_t);
 };
 
-typedef struct _ink_freelist_list {
+using ink_freelist_list = struct _ink_freelist_list {
   InkFreeList *fl;
   struct _ink_freelist_list *next;
-} ink_freelist_list;
+};
 
 static void *freelist_new(InkFreeList *f);
 static void freelist_free(InkFreeList *f, void *item);
diff --git a/src/tscore/unit_tests/test_layout.cc b/src/tscore/unit_tests/test_layout.cc
index 736393bd847..1305d939db6 100644
--- a/src/tscore/unit_tests/test_layout.cc
+++ b/src/tscore/unit_tests/test_layout.cc
@@ -29,8 +29,9 @@ std::string
 append_slash(const char *path)
 {
   std::string ret(path);
-  if (ret.back() != '/')
+  if (ret.back() != '/') {
     ret.append("/");
+  }
   return ret;
 }