diff --git a/include/upa/str_arg.h b/include/upa/str_arg.h
index d330988..4e96180 100644
--- a/include/upa/str_arg.h
+++ b/include/upa/str_arg.h
@@ -36,19 +36,19 @@ using string_view = std::string_view;
 
 template<class CharT>
 struct is_char_type : std::integral_constant<bool,
-    std::is_same<CharT, char>::value ||
+    std::is_same_v<CharT, char> ||
 #ifdef __cpp_char8_t
-    std::is_same<CharT, char8_t>::value ||
+    std::is_same_v<CharT, char8_t> ||
 #endif
-    std::is_same<CharT, char16_t>::value ||
-    std::is_same<CharT, char32_t>::value ||
-    std::is_same<CharT, wchar_t>::value
+    std::is_same_v<CharT, char16_t> ||
+    std::is_same_v<CharT, char32_t> ||
+    std::is_same_v<CharT, wchar_t>
 > {};
 
 template<class SizeT>
 struct is_size_type : std::integral_constant<bool,
-    std::is_convertible<SizeT, std::size_t>::value ||
-    std::is_convertible<SizeT, std::ptrdiff_t>::value
+    std::is_convertible_v<SizeT, std::size_t> ||
+    std::is_convertible_v<SizeT, std::ptrdiff_t>
 > {};
 
 
@@ -62,14 +62,14 @@ class str_arg {
     // output value type
     using value_type =
         // wchar_t type will be converted to char16_t or char32_t type equivalent by size
-        typename std::conditional<std::is_same<CharT, wchar_t>::value, std::conditional<sizeof(wchar_t) == sizeof(char16_t), char16_t, char32_t>::type,
+        std::conditional_t<std::is_same_v<CharT, wchar_t>, std::conditional_t<sizeof(wchar_t) == sizeof(char16_t), char16_t, char32_t>,
 #ifdef __cpp_char8_t
         // char8_t type will be converted to char type
-        typename std::conditional<std::is_same<CharT, char8_t>::value, char, input_type>::type
+        std::conditional_t<std::is_same_v<CharT, char8_t>, char, input_type>
 #else
         input_type
 #endif
-        >::type;
+        >;
 
     // constructors
     str_arg(const str_arg&) noexcept = default;
@@ -123,7 +123,7 @@ class str_arg {
 // String type helpers
 
 template<class T>
-using remove_cvptr_t = typename std::remove_cv<typename std::remove_pointer<T>::type>::type;
+using remove_cvptr_t = std::remove_cv_t<std::remove_pointer_t<T>>;
 
 namespace detail {
     // See: https://stackoverflow.com/a/9154394
@@ -170,7 +170,7 @@ struct str_arg_char<CharT*, CharT*> : std::remove_cv<CharT> {
 template<class CharT, class SizeT>
 struct str_arg_char<CharT*, SizeT> : std::enable_if<
     is_size_type<SizeT>::value,
-    typename std::remove_cv<CharT>::type> {
+    std::remove_cv_t<CharT>> {
 
     template <typename T>
     static str_arg<T> to_str_arg(const T* s, std::size_t length) {
@@ -191,7 +191,7 @@ struct str_arg_char<CharT*> : std::remove_cv<CharT> {
 // one string class argument
 template<class StrT>
 struct str_arg_char<StrT> : std::enable_if<
-    std::is_pointer<detail::data_member_t<StrT>>::value &&
+    std::is_pointer_v<detail::data_member_t<StrT>> &&
     is_size_type<detail::length_member_t<StrT>>::value,
     remove_cvptr_t<detail::data_member_t<StrT>>> {
 
@@ -205,16 +205,16 @@ struct str_arg_char<StrT> : std::enable_if<
 // String arguments helper types
 
 template<class ...Args>
-using str_arg_char_s = str_arg_char<typename std::decay<Args>::type...>;
+using str_arg_char_s = str_arg_char<std::decay_t<Args>...>;
 
 template<class ...Args>
 using str_arg_char_t = typename str_arg_char_s<Args...>::type;
 
 
 template<class ...Args>
-using enable_if_str_arg_t = typename std::enable_if<
+using enable_if_str_arg_t = std::enable_if_t<
     is_char_type<str_arg_char_t<Args...>>::value,
-    int>::type;
+    int>;
 
 
 // String arguments helper function
@@ -229,28 +229,28 @@ inline auto make_str_arg(Args&&... args) -> str_arg<str_arg_char_t<Args...>> {
 
 template<class CharT>
 struct is_char8_type : std::integral_constant<bool,
-    std::is_same<CharT, char>::value
+    std::is_same_v<CharT, char>
 #ifdef __cpp_char8_t
-    || std::is_same<CharT, char8_t>::value
+    || std::is_same_v<CharT, char8_t>
 #endif
 > {};
 
 template<class ...Args>
-using enable_if_str_arg_to_char8_t = typename std::enable_if<
+using enable_if_str_arg_to_char8_t = std::enable_if_t<
     is_char8_type<str_arg_char_t<Args...>>::value,
-    int>::type;
+    int>;
 
 template<class CharT>
 struct is_charW_type : std::integral_constant<bool,
-    std::is_same<CharT, char16_t>::value ||
-    std::is_same<CharT, char32_t>::value ||
-    std::is_same<CharT, wchar_t>::value
+    std::is_same_v<CharT, char16_t> ||
+    std::is_same_v<CharT, char32_t> ||
+    std::is_same_v<CharT, wchar_t>
 > {};
 
 template<class ...Args>
-using enable_if_str_arg_to_charW_t = typename std::enable_if<
+using enable_if_str_arg_to_charW_t = std::enable_if_t<
     is_charW_type<str_arg_char_t<Args...>>::value,
-    int>::type;
+    int>;
 
 
 inline std::string&& make_string(std::string&& str) {
diff --git a/include/upa/url.h b/include/upa/url.h
index cb2170f..bf405b0 100644
--- a/include/upa/url.h
+++ b/include/upa/url.h
@@ -1601,7 +1601,7 @@ namespace detail {
 template <typename CharT>
 inline validation_errc url_parser::url_parse(url_serializer& urls, const CharT* first, const CharT* last, const url* base, State state_override)
 {
-    using UCharT = typename std::make_unsigned<CharT>::type;
+    using UCharT = std::make_unsigned_t<CharT>;
 
     // remove all ASCII tab or newline from URL
     simple_buffer<CharT> buff_no_ws;
@@ -2393,7 +2393,7 @@ inline void url_parser::parse_path(url_serializer& urls, const CharT* first, con
 
 template <typename CharT>
 inline bool url_parser::do_path_segment(const CharT* pointer, const CharT* last, std::string& output) {
-    using UCharT = typename std::make_unsigned<CharT>::type;
+    using UCharT = std::make_unsigned_t<CharT>;
 
     // TODO-WARN: 2. [ 1 ... 2 ] validation error.
     bool success = true;
@@ -2418,7 +2418,7 @@ inline bool url_parser::do_path_segment(const CharT* pointer, const CharT* last,
 
 template <typename CharT>
 inline bool url_parser::do_simple_path(const CharT* pointer, const CharT* last, std::string& output) {
-    using UCharT = typename std::make_unsigned<CharT>::type;
+    using UCharT = std::make_unsigned_t<CharT>;
 
     // 3. of "opaque path state"
     // TODO-WARN: 3. [ 1 ... 2 ] validation error.
diff --git a/include/upa/url_host.h b/include/upa/url_host.h
index 427ea75..20a7191 100644
--- a/include/upa/url_host.h
+++ b/include/upa/url_host.h
@@ -157,7 +157,7 @@ inline bool contains_forbidden_host_char(const CharT* first, const CharT* last)
 
 template <typename CharT>
 inline validation_errc host_parser::parse_host(const CharT* first, const CharT* last, bool is_opaque, host_output& dest) {
-    using UCharT = typename std::make_unsigned<CharT>::type;
+    using UCharT = std::make_unsigned_t<CharT>;
 
     // 1. Non-"file" special URL's cannot have an empty host.
     // 2. For "file" URL's empty host is set in the file_host_state 1.2
@@ -314,7 +314,7 @@ inline validation_errc host_parser::parse_opaque_host(const CharT* first, const
 
         //TODO: UTF-8 percent encode it using the C0 control percent-encode set
         //detail::append_utf8_percent_encoded(first, last, detail::CHAR_C0_CTRL, str_host);
-        using UCharT = typename std::make_unsigned<CharT>::type;
+        using UCharT = std::make_unsigned_t<CharT>;
 
         const CharT* pointer = first;
         while (pointer < last) {
diff --git a/include/upa/url_ip.h b/include/upa/url_ip.h
index 4e14924..7c614e9 100644
--- a/include/upa/url_ip.h
+++ b/include/upa/url_ip.h
@@ -133,7 +133,7 @@ inline validation_errc ipv4_parse_number(const CharT* first, const CharT* last,
 //
 template <typename CharT>
 inline validation_errc ipv4_parse(const CharT* first, const CharT* last, uint32_t& ipv4) {
-    using UCharT = typename std::make_unsigned<CharT>::type;
+    using UCharT = std::make_unsigned_t<CharT>;
 
     // 2. If the last item in parts is the empty string, then
     //    1. IPv4-empty-part validation error. (TODO-WARN)
diff --git a/include/upa/url_percent_encode.h b/include/upa/url_percent_encode.h
index caee479..4d7de0c 100644
--- a/include/upa/url_percent_encode.h
+++ b/include/upa/url_percent_encode.h
@@ -425,7 +425,7 @@ inline bool append_utf8_percent_encoded_char(const CharT*& first, const CharT* l
 
 template<typename CharT>
 inline void append_utf8_percent_encoded(const CharT* first, const CharT* last, const code_point_set& cpset, std::string& output) {
-    using UCharT = typename std::make_unsigned<CharT>::type;
+    using UCharT = std::make_unsigned_t<CharT>;
 
     for (auto it = first; it < last; ) {
         const auto uch = static_cast<UCharT>(*it);
diff --git a/include/upa/url_search_params.h b/include/upa/url_search_params.h
index 0f8ee23..2d43b75 100644
--- a/include/upa/url_search_params.h
+++ b/include/upa/url_search_params.h
@@ -41,9 +41,9 @@ template <typename T>
 auto iterable_value(long) -> void;
 
 template<class T>
-using iterable_value_t = typename std::remove_cv<typename std::remove_reference<
+using iterable_value_t = std::remove_cv_t<std::remove_reference_t<
     decltype(iterable_value<T>(0))
->::type>::type;
+>>;
 
 // is iterable over the std::pair values
 template<class T>
@@ -51,9 +51,9 @@ struct is_iterable_pairs : is_pair<iterable_value_t<T>> {};
 
 // enable if `Base` is not the base class of `T`
 template<class Base, class T>
-using enable_if_not_base_of_t = typename std::enable_if<
-    !std::is_base_of<Base, typename std::decay<T>::type>::value, int
->::type;
+using enable_if_not_base_of_t = std::enable_if_t<
+    !std::is_base_of_v<Base, std::decay_t<T>>, int
+>;
 
 } // namespace detail
 
@@ -102,7 +102,7 @@ class url_search_params
     ///
     /// @param[in,out] other @c url_search_params object to move from
     url_search_params(url_search_params&& other)
-        noexcept(std::is_nothrow_move_constructible<name_value_list>::value);
+        noexcept(std::is_nothrow_move_constructible_v<name_value_list>);
 
     /// @brief Parsing constructor.
     ///
@@ -120,7 +120,7 @@ class url_search_params
     template<class ConT,
         // do not hide the copy and move constructors:
         detail::enable_if_not_base_of_t<url_search_params, ConT> = 0,
-        typename std::enable_if<detail::is_iterable_pairs<ConT>::value, int>::type = 0
+        std::enable_if_t<detail::is_iterable_pairs<ConT>::value, int> = 0
     >
     explicit url_search_params(ConT&& cont) {
         for (const auto& p : cont) {
@@ -447,7 +447,7 @@ inline url_search_params::url_search_params(const url_search_params& other)
 // Move constructor
 
 inline url_search_params::url_search_params(url_search_params&& other)
-    noexcept(std::is_nothrow_move_constructible<name_value_list>::value)
+    noexcept(std::is_nothrow_move_constructible_v<name_value_list>)
     : params_(std::move(other.params_))
     , is_sorted_(other.is_sorted_)
 {}
diff --git a/include/upa/util.h b/include/upa/util.h
index 59a3caf..49c02bd 100644
--- a/include/upa/util.h
+++ b/include/upa/util.h
@@ -24,7 +24,7 @@ namespace upa::util {
 // __attribute__((no_sanitize("unsigned-integer-overflow"))).
 
 // Utility class to get unsigned (abs) max, min values of (signed) integer type
-template <typename T, typename UT = typename std::make_unsigned<T>::type>
+template <typename T, typename UT = std::make_unsigned_t<T>>
 struct unsigned_limit {
     static constexpr UT max() noexcept {
         return static_cast<UT>(std::numeric_limits<T>::max());
@@ -46,8 +46,8 @@ struct unsigned_limit {
 // Returns difference between a and b (a - b), if result is not representable
 // by the type Out - throws exception.
 template <typename Out, typename T,
-    typename UT = typename std::make_unsigned<T>::type,
-    typename std::enable_if<std::is_integral<T>::value, int>::type = 0>
+    typename UT = std::make_unsigned_t<T>,
+    std::enable_if_t<std::is_integral_v<T>, int> = 0>
 #if defined(__clang__)
 __attribute__((no_sanitize("unsigned-integer-overflow")))
 #endif
@@ -56,7 +56,7 @@ inline Out checked_diff(T a, T b) {
         const UT diff = static_cast<UT>(static_cast<UT>(a) - static_cast<UT>(b));
         if (diff <= unsigned_limit<Out>::max())
             return static_cast<Out>(diff);
-    } else if (std::is_signed<Out>::value) {
+    } else if (std::is_signed_v<Out>) {
         // b > a ==> diff >= 1
         const UT diff = static_cast<UT>(static_cast<UT>(b) - static_cast<UT>(a));
         if (diff <= unsigned_limit<Out>::min())
@@ -67,7 +67,7 @@ inline Out checked_diff(T a, T b) {
 
 // Cast integer value to corresponding unsigned type
 
-template <typename T, typename UT = typename std::make_unsigned<T>::type>
+template <typename T, typename UT = std::make_unsigned_t<T>>
 constexpr auto to_unsigned(T n) noexcept -> UT {
     return static_cast<UT>(n);
 }
@@ -105,14 +105,14 @@ inline std::size_t add_sizes(std::size_t size1, std::size_t size2, std::size_t m
 #ifdef _MSC_VER
 // the value_type of dest and src are the same (char)
 template <class StrT,
-    typename std::enable_if<std::is_same<typename StrT::value_type, char>::value, int>::type = 0>
+    std::enable_if_t<std::is_same_v<typename StrT::value_type, char>, int> = 0>
 inline void append(std::string& dest, const StrT& src) {
     dest.append(src.begin(), src.end());
 }
 
 // the value_type of dest and src are different
 template <class StrT,
-    typename std::enable_if<!std::is_same<typename StrT::value_type, char>::value, int>::type = 0>
+    std::enable_if_t<!std::is_same_v<typename StrT::value_type, char>, int> = 0>
 inline void append(std::string& dest, const StrT& src) {
     dest.reserve(add_sizes(dest.size(), src.size(), dest.max_size()));
     for (const auto c : src)