diff --git a/include/gsl/span b/include/gsl/span
index 8536cf7..6c1b2cd 100644
--- a/include/gsl/span
+++ b/include/gsl/span
@@ -164,67 +164,67 @@ namespace details
             return span_->data() + index_;
         }
 
-        constexpr span_iterator& operator++()
+        constexpr span_iterator& operator++() noexcept
         {
             Expects(0 <= index_ && index_ != span_->size());
             ++index_;
             return *this;
         }
 
-        constexpr span_iterator operator++(int)
+        constexpr span_iterator operator++(int) noexcept
         {
             auto ret = *this;
             ++(*this);
             return ret;
         }
 
-        constexpr span_iterator& operator--()
+        constexpr span_iterator& operator--() noexcept
         {
             Expects(index_ != 0 && index_ <= span_->size());
             --index_;
             return *this;
         }
 
-        constexpr span_iterator operator--(int)
+        constexpr span_iterator operator--(int) noexcept
         {
             auto ret = *this;
             --(*this);
             return ret;
         }
 
-        constexpr span_iterator operator+(difference_type n) const
+        constexpr span_iterator operator+(difference_type n) const noexcept
         {
             auto ret = *this;
             return ret += n;
         }
 
-        friend constexpr span_iterator operator+(difference_type n, span_iterator const& rhs)
+        friend constexpr span_iterator operator+(difference_type n, span_iterator const& rhs) noexcept
         {
             return rhs + n;
         }
 
-        constexpr span_iterator& operator+=(difference_type n)
+        constexpr span_iterator& operator+=(difference_type n) noexcept
         {
             Expects((index_ + n) >= 0 && (index_ + n) <= span_->size());
             index_ += n;
             return *this;
         }
 
-        constexpr span_iterator operator-(difference_type n) const
+        constexpr span_iterator operator-(difference_type n) const noexcept
         {
             auto ret = *this;
             return ret -= n;
         }
 
-        constexpr span_iterator& operator-=(difference_type n) { return *this += -n; }
+        constexpr span_iterator& operator-=(difference_type n) noexcept { return *this += -n; }
 
-        constexpr difference_type operator-(span_iterator rhs) const
+        constexpr difference_type operator-(span_iterator rhs) const noexcept
         {
             Expects(span_ == rhs.span_);
             return index_ - rhs.index_;
         }
 
-        constexpr reference operator[](difference_type n) const { return *(*this + n); }
+        constexpr reference operator[](difference_type n) const noexcept { return *(*this + n); }
 
         constexpr friend bool operator==(span_iterator lhs, span_iterator rhs) noexcept
         {
@@ -383,9 +383,9 @@ public:
     constexpr span() noexcept : storage_(nullptr, details::extent_type<0>())
     {}
 
-    constexpr span(pointer ptr, index_type count) : storage_(ptr, count) {}
+    constexpr span(pointer ptr, index_type count) noexcept: storage_(ptr, count) {}
 
-    constexpr span(pointer firstElem, pointer lastElem)
+    constexpr span(pointer firstElem, pointer lastElem) noexcept
         : storage_(firstElem, std::distance(firstElem, lastElem))
     {}
 
@@ -424,7 +424,7 @@ public:
                   std::is_convertible<typename Container::pointer, pointer>::value &&
                   std::is_convertible<typename Container::pointer,
                                       decltype(std::declval<Container>().data())>::value>>
-    constexpr span(Container& cont) : span(cont.data(), narrow<index_type>(cont.size()))
+    constexpr span(Container& cont) noexcept : span(cont.data(), narrow<index_type>(cont.size()))
     {}
 
     template <class Container,
@@ -433,7 +433,7 @@ public:
                   std::is_convertible<typename Container::pointer, pointer>::value &&
                   std::is_convertible<typename Container::pointer,
                                       decltype(std::declval<Container>().data())>::value>>
-    constexpr span(const Container& cont) : span(cont.data(), narrow<index_type>(cont.size()))
+    constexpr span(const Container& cont) noexcept : span(cont.data(), narrow<index_type>(cont.size()))
     {}
 
     constexpr span(const span& other) noexcept = default;
@@ -443,7 +443,7 @@ public:
         class = std::enable_if_t<
             details::is_allowed_extent_conversion<OtherExtent, Extent>::value &&
             details::is_allowed_element_type_conversion<OtherElementType, element_type>::value>>
-    constexpr span(const span<OtherElementType, OtherExtent>& other)
+    constexpr span(const span<OtherElementType, OtherExtent>& other) noexcept
         : storage_(other.data(), details::extent_type<OtherExtent>(other.size()))
     {}
 
@@ -452,7 +452,7 @@ public:
 
     // [span.sub], span subviews
     template <std::ptrdiff_t Count>
-    constexpr span<element_type, Count> first() const
+    constexpr span<element_type, Count> first() const noexcept
     {
         Expects(Count >= 0 && Count <= size());
         return {data(), Count};
@@ -460,7 +460,7 @@ public:
 
     template <std::ptrdiff_t Count>
     GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
-    constexpr span<element_type, Count> last() const
+    constexpr span<element_type, Count> last() const noexcept
     {
         Expects(Count >= 0 && size() - Count >= 0);
         return {data() + (size() - Count), Count};
@@ -468,7 +468,7 @@ public:
 
     template <std::ptrdiff_t Offset, std::ptrdiff_t Count = dynamic_extent>
     GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
-    constexpr auto subspan() const ->
+    constexpr auto subspan() const noexcept ->
         typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type
     {
         Expects((Offset >= 0 && size() - Offset >= 0) &&
@@ -477,19 +477,19 @@ public:
         return {data() + Offset, Count == dynamic_extent ? size() - Offset : Count};
     }
 
-    constexpr span<element_type, dynamic_extent> first(index_type count) const
+    constexpr span<element_type, dynamic_extent> first(index_type count) const noexcept
     {
         Expects(count >= 0 && count <= size());
         return {data(), count};
     }
 
-    constexpr span<element_type, dynamic_extent> last(index_type count) const
+    constexpr span<element_type, dynamic_extent> last(index_type count) const noexcept
     {
         return make_subspan(size() - count, dynamic_extent, subspan_selector<Extent>{});
     }
 
     constexpr span<element_type, dynamic_extent> subspan(index_type offset,
-                                                         index_type count = dynamic_extent) const
+                                                         index_type count = dynamic_extent) const noexcept
     {
         return make_subspan(offset, count, subspan_selector<Extent>{});
     }
@@ -504,15 +504,12 @@ public:
 
     // [span.elem], span element access
     GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
-    constexpr reference operator[](index_type idx) const
+    constexpr reference operator[](index_type idx) const noexcept
     {
         Expects(CheckRange(idx, storage_.size()));
         return data()[idx];
     }
 
-    constexpr reference at(index_type idx) const { return this->operator[](idx); }
-    constexpr reference operator()(index_type idx) const { return this->operator[](idx); }
-
     constexpr reference front() const noexcept
     {
         Expects(size() > 0);
@@ -525,6 +522,10 @@ public:
         return data()[size() - 1];
     }
 
+
+    constexpr reference at(index_type idx) const noexcept{ return this->operator[](idx); }
+    constexpr reference operator()(index_type idx) const noexcept{ return this->operator[](idx); }
+
     constexpr pointer data() const noexcept { return storage_.data(); }
 
     // [span.iter], span iterator support
@@ -787,6 +788,62 @@ constexpr ElementType& at(span<ElementType, Extent> s, index i)
     return s[i];
 }
 
+// [span.obs] Free observer functions
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::index_type ssize(const span<ElementType, Extent> &span) noexcept
+{
+    return span.size();
+}
+
+// [span.iter] Free functions for begin/end functions
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::iterator begin(const span<ElementType, Extent> &span) noexcept
+{
+    return span.begin();
+}
+
+template <class ElementType, std::ptrdiff_t Extent = dynamic_extent>
+constexpr typename span<ElementType, Extent>::iterator end(const span<ElementType, Extent> &span) noexcept
+{
+    return span.end();
+}
+
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::const_iterator cbegin(const span<ElementType, Extent> &span) noexcept
+{
+    return span.cbegin();
+}
+
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::const_iterator cend(const span<ElementType, Extent> &span) noexcept
+{
+    return span.cend();
+}
+
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::reverse_iterator rbegin(const span<ElementType, Extent> &span) noexcept
+{
+    return span.rbegin();
+}
+
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::reverse_iterator rend(const span<ElementType, Extent> &span) noexcept
+{
+    return span.rend();
+}
+
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::const_reverse_iterator crbegin(const span<ElementType, Extent> &span) noexcept
+{
+    return span.crbegin();
+}
+
+template <class ElementType, std::ptrdiff_t Extent>
+constexpr typename span<ElementType, Extent>::const_reverse_iterator crend(const span<ElementType, Extent> &span) noexcept
+{
+    return span.crend();
+}
+
 } // namespace gsl
 
 #if defined(_MSC_VER) && !defined(__clang__)
diff --git a/tests/span_tests.cpp b/tests/span_tests.cpp
index ebeb685..5885328 100644
--- a/tests/span_tests.cpp
+++ b/tests/span_tests.cpp
@@ -1084,6 +1084,45 @@ TEST(span_test, from_array_constructor)
      EXPECT_TRUE(cit3 == s.cend());
  }
 
+ TEST(span_test, iterator_free_functions)
+ {
+     int a[] = {1, 2, 3, 4};
+     span<int> s{a};
+ 
+     EXPECT_TRUE((std::is_same<decltype(s.begin()), decltype(begin(s))>::value));
+     EXPECT_TRUE((std::is_same<decltype(s.end()), decltype(end(s))>::value));
+ 
+     EXPECT_TRUE((std::is_same<decltype(s.cbegin()), decltype(cbegin(s))>::value));
+     EXPECT_TRUE((std::is_same<decltype(s.cend()), decltype(cend(s))>::value));
+ 
+     EXPECT_TRUE((std::is_same<decltype(s.rbegin()), decltype(rbegin(s))>::value));
+     EXPECT_TRUE((std::is_same<decltype(s.rend()), decltype(rend(s))>::value));
+ 
+     EXPECT_TRUE((std::is_same<decltype(s.crbegin()), decltype(crbegin(s))>::value));
+     EXPECT_TRUE((std::is_same<decltype(s.crend()), decltype(crend(s))>::value));
+ 
+     EXPECT_TRUE(s.begin() == begin(s));
+     EXPECT_TRUE(s.end() == end(s));
+ 
+     EXPECT_TRUE(s.cbegin() == cbegin(s));
+     EXPECT_TRUE(s.cend() == cend(s));
+ 
+     EXPECT_TRUE(s.rbegin() == rbegin(s));
+     EXPECT_TRUE(s.rend() == rend(s));
+ 
+     EXPECT_TRUE(s.crbegin() == crbegin(s));
+     EXPECT_TRUE(s.crend() == crend(s));
+ }
+
+ TEST(span_test, ssize_free_function)
+ {
+     int a[] = {1, 2, 3, 4};
+     span<int> s{a};
+ 
+     EXPECT_TRUE((std::is_same<decltype(s.size()), decltype(ssize(s))>::value));
+     EXPECT_TRUE(s.size() == ssize(s));
+ }
+
  TEST(span_test, iterator_comparisons)
  {
      int a[] = {1, 2, 3, 4};