diff --git a/include/hibf/misc/insert_iterator.hpp b/include/hibf/misc/insert_iterator.hpp
index 903869a0..72719598 100644
--- a/include/hibf/misc/insert_iterator.hpp
+++ b/include/hibf/misc/insert_iterator.hpp
@@ -20,6 +20,17 @@
 namespace seqan::hibf
 {
 
+// hibf/interleaved_bloom_filter.hpp includes config.hpp, which includes insert_iterator.hpp
+// Hence, we need a forward declaration.
+class interleaved_bloom_filter;
+
+namespace sketch
+{
+
+class hyperloglog;
+
+}
+
 class insert_iterator
 {
 public:
@@ -29,35 +40,34 @@ class insert_iterator
     using pointer = void;
     using reference = void;
 
-    insert_iterator() = delete;
-    insert_iterator(insert_iterator const &) = default;
-    insert_iterator(insert_iterator &&) = default;
-    insert_iterator & operator=(insert_iterator const &) = default;
-    insert_iterator & operator=(insert_iterator &&) = default;
-    ~insert_iterator() = default;
+    constexpr insert_iterator() = default;
+    constexpr insert_iterator(insert_iterator const &) = default;
+    constexpr insert_iterator(insert_iterator &&) = default;
+    constexpr insert_iterator & operator=(insert_iterator const &) = default;
+    constexpr insert_iterator & operator=(insert_iterator &&) = default;
+    constexpr ~insert_iterator() = default;
+
+    using set_t = robin_hood::unordered_flat_set<uint64_t>;
+    using sketch_t = sketch::hyperloglog;
+    using ibf_t = interleaved_bloom_filter;
+    using function_t = std::function<void(uint64_t const)>;
 
-    explicit constexpr insert_iterator(robin_hood::unordered_flat_set<uint64_t> & set) :
-        set{std::addressof(set)},
-        is_set{true}
+    explicit constexpr insert_iterator(set_t & set) : ptr{std::addressof(set)}, type{data_type::unordered_set}
     {}
 
-    explicit constexpr insert_iterator(std::vector<uint64_t> & vec) : vec{std::addressof(vec)}, is_set{false}
+    explicit constexpr insert_iterator(sketch_t & sketch) : ptr{std::addressof(sketch)}, type{data_type::sketch}
     {}
 
-    insert_iterator & operator=(uint64_t const value) noexcept
-    {
-        if (is_set)
-        {
-            assert(set != nullptr);
-            set->emplace(value);
-        }
-        else
-        {
-            assert(vec != nullptr);
-            vec->emplace_back(value);
-        }
-        return *this;
-    }
+    explicit constexpr insert_iterator(ibf_t & ibf, size_t ibf_bin_index) :
+        ptr{std::addressof(ibf)},
+        ibf_bin_index{ibf_bin_index},
+        type{data_type::ibf}
+    {}
+
+    constexpr insert_iterator(function_t & fun) : ptr{std::addressof(fun)}, type{data_type::function}
+    {}
+
+    insert_iterator & operator=(uint64_t const value) noexcept;
 
     [[nodiscard]] constexpr insert_iterator & operator*() noexcept
     {
@@ -75,9 +85,18 @@ class insert_iterator
     }
 
 private:
-    robin_hood::unordered_flat_set<uint64_t> * set{nullptr};
-    std::vector<uint64_t> * vec{nullptr};
-    bool is_set{false};
+    void * ptr{nullptr};
+
+    enum class data_type : uint8_t
+    {
+        unordered_set,
+        sketch,
+        ibf,
+        function
+    };
+
+    size_t ibf_bin_index{};
+    data_type type{};
 };
 
 } // namespace seqan::hibf
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9d240b38..aab05f8f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -15,6 +15,7 @@ set (HIBF_SOURCE_FILES
      sketch/compute_sketches.cpp
      layout/graph.cpp
      layout/hierarchical_binning.cpp
+     misc/insert_iterator.cpp
      misc/print.cpp
      sketch/toolbox.cpp
      sketch/hyperloglog.cpp
diff --git a/src/misc/insert_iterator.cpp b/src/misc/insert_iterator.cpp
new file mode 100644
index 00000000..c04d9025
--- /dev/null
+++ b/src/misc/insert_iterator.cpp
@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: 2006-2024, Knut Reinert & Freie Universität Berlin
+// SPDX-FileCopyrightText: 2016-2024, Knut Reinert & MPI für molekulare Genetik
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <cassert>     // for assert
+#include <cmath>       // for ceil, sqrt
+#include <functional>  // for function
+#include <iostream>    // for operator<<, basic_ostream, basic_istream, getline, stringstream
+#include <sstream>     // for basic_stringstream
+#include <stdexcept>   // for invalid_argument
+#include <string>      // for char_traits, string
+#include <string_view> // for operator==, basic_string_view, string_view
+
+#include <cereal/archives/json.hpp> // for JSONInputArchive, JSONOutputArchive
+#include <cereal/cereal.hpp>        // for make_nvp, InputArchive, OutputArchive
+
+#include <hibf/interleaved_bloom_filter.hpp>
+#include <hibf/misc/insert_iterator.hpp> // for insert_iterator
+#include <hibf/sketch/hyperloglog.hpp>
+
+namespace seqan::hibf
+{
+
+// Inlining std::function produces overhead which affects the other cases.
+[[gnu::noinline]] void invoke_without_inlining(void * const ptr, uint64_t const value)
+{
+    static_cast<typename insert_iterator::function_t *>(ptr)->operator()(value);
+}
+
+#if HIBF_COMPILER_IS_GCC
+#    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wattributes"
+#endif // HIBF_COMPILER_IS_GCC
+[[gnu::always_inline]] insert_iterator & insert_iterator::operator=(uint64_t const value) noexcept
+{
+#if HIBF_COMPILER_IS_GCC
+#    pragma GCC diagnostic pop
+#endif // HIBF_COMPILER_IS_GCC
+    assert(ptr != nullptr);
+
+    switch (type)
+    {
+    case data_type::unordered_set:
+        static_cast<set_t *>(ptr)->emplace(value);
+        break;
+    case data_type::sketch:
+        static_cast<sketch_t *>(ptr)->add(value);
+        break;
+    case data_type::ibf:
+        static_cast<ibf_t *>(ptr)->emplace(value, static_cast<bin_index>(ibf_bin_index));
+        break;
+    case data_type::function:
+        invoke_without_inlining(ptr, value);
+        break;
+    default: // GCOVR_EXCL_LINE
+#ifndef NDEBUG
+        assert(false); // GCOVR_EXCL_LINE
+#else
+        __builtin_unreachable();
+#endif
+    }
+    return *this;
+}
+
+} // namespace seqan::hibf
diff --git a/test/unit/hibf/CMakeLists.txt b/test/unit/hibf/CMakeLists.txt
index ee8ff489..49da8e71 100644
--- a/test/unit/hibf/CMakeLists.txt
+++ b/test/unit/hibf/CMakeLists.txt
@@ -9,6 +9,7 @@ hibf_test (config_test.cpp)
 hibf_test (counting_vector_test.cpp)
 hibf_test (counting_vector_avx512_test.cpp)
 hibf_test (hierarchical_interleaved_bloom_filter_test.cpp)
+hibf_test (insert_iterator_test.cpp)
 hibf_test (interleaved_bloom_filter_test.cpp)
 hibf_test (interleaved_bloom_filter_avx512_test.cpp)
 hibf_test (path_test.cpp)
diff --git a/test/unit/hibf/insert_iterator_test.cpp b/test/unit/hibf/insert_iterator_test.cpp
new file mode 100644
index 00000000..fc89e66e
--- /dev/null
+++ b/test/unit/hibf/insert_iterator_test.cpp
@@ -0,0 +1,58 @@
+// SPDX-FileCopyrightText: 2006-2024, Knut Reinert & Freie Universität Berlin
+// SPDX-FileCopyrightText: 2016-2024, Knut Reinert & MPI für molekulare Genetik
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <gtest/gtest.h> // for Message, TestPartResult, AssertionResult, Test, EXPECT_EQ, Capture...
+
+#include <hibf/interleaved_bloom_filter.hpp>
+#include <hibf/misc/insert_iterator.hpp>
+#include <hibf/sketch/hyperloglog.hpp>
+#include <hibf/test/expect_range_eq.hpp> // for expect_range_eq, EXPECT_RANGE_EQ
+
+static constexpr std::array<size_t, 10> values{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+
+TEST(insert_iterator_test, unordered_set)
+{
+    robin_hood::unordered_flat_set<uint64_t> target;
+    seqan::hibf::insert_iterator it{target};
+    std::ranges::copy(values, it);
+    EXPECT_EQ(target.size(), 10u);
+}
+
+TEST(insert_iterator_test, sketch)
+{
+    seqan::hibf::sketch::hyperloglog target{5u};
+    seqan::hibf::insert_iterator it{target};
+    std::ranges::copy(values, it);
+    EXPECT_NEAR(target.estimate(), 11.99, 0.001);
+}
+
+TEST(insert_iterator_test, ibf)
+{
+    seqan::hibf::interleaved_bloom_filter target{seqan::hibf::bin_count{8u},
+                                                 seqan::hibf::bin_size{8u},
+                                                 seqan::hibf::hash_function_count{1u}};
+    for (size_t i = 0; i < 3; ++i)
+    {
+        seqan::hibf::insert_iterator it{target, i};
+        std::ranges::copy(values, it);
+    }
+
+    auto agent = target.counting_agent<uint8_t>();
+    auto & result = agent.bulk_count(values);
+    std::vector<uint8_t> const expected{10, 10, 10, 0, 0, 0, 0, 0};
+    EXPECT_RANGE_EQ(result, expected);
+}
+
+TEST(insert_iterator_test, function)
+{
+    robin_hood::unordered_flat_set<uint64_t> target;
+    std::function<void(uint64_t const)> fun = [&target](size_t const value)
+    {
+        target.emplace(value);
+        target.emplace((1u + value) * 11u);
+    };
+    seqan::hibf::insert_iterator it{fun};
+    std::ranges::copy(values, it);
+    EXPECT_EQ(target.size(), 20);
+}