diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index d4502a5c96..1386cc7a96 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -5254,6 +5254,57 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         }
     }
 
+    /// @brief creates a diff as a JSON Merge Patch
+    JSON_HEDLEY_WARN_UNUSED_RESULT
+    static basic_json merge_diff(const basic_json& source, const basic_json& target)
+    {
+        if (!target.is_object())
+        {
+            return target;
+        }
+
+        basic_json result(value_t::object);
+
+        if (source.is_object())
+        {
+            for (auto it = source.begin(); it != source.end(); ++it)
+            {
+                auto itf = target.find(it.key());
+                if (itf != target.end())
+                {
+                    if (it.value() != itf.value())
+                    {
+                        auto diff = merge_diff(it.value(), itf.value());
+                        if (diff.is_null())
+                        {
+                            JSON_THROW(other_error::create(503, detail::concat("cannot set \"", itf.key(), "\" to null"), &target));
+                        }
+                        result[it.key()] = merge_diff(it.value(), itf.value());
+                    }
+                }
+                else
+                {
+                    result[it.key()] = value_t::null;
+                }
+            }
+        }
+
+        for (auto it = target.begin(); it != target.end(); ++it)
+        {
+            auto itf = source.find(it.key());
+            if (itf == source.end())
+            {
+                if (it.value().is_null())
+                {
+                    JSON_THROW(other_error::create(503, detail::concat("cannot set \"", it.key(), "\" to null"), &target));
+                }
+                result[it.key()] = it.value();
+            }
+        }
+
+        return result;
+    }
+
     /// @}
 };
 
diff --git a/tests/src/unit-merge_diff.cpp b/tests/src/unit-merge_diff.cpp
new file mode 100644
index 0000000000..18a8455550
--- /dev/null
+++ b/tests/src/unit-merge_diff.cpp
@@ -0,0 +1,433 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2025 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+#ifdef JSON_TEST_NO_GLOBAL_UDLS
+    using namespace nlohmann::literals; // NOLINT(google-build-using-namespace)
+#endif
+
+TEST_CASE("JSON Merge Patch")
+{
+    SECTION("examples from RFC 7396")
+    {
+        SECTION("Section 1")
+        {
+            json document = R"({
+                "a": "b",
+                "c": {
+                    "d": "e",
+                    "f": "g"
+                }
+            })"_json;
+
+            json expected = R"({
+                "a": "z",
+                "c": {
+                    "d": "e"
+                }
+            })"_json;
+
+            document.merge_patch(json::merge_diff(document, expected));
+            CHECK(document == expected);
+        }
+
+        SECTION("Section 3")
+        {
+            json document = R"({
+                "title": "Goodbye!",
+                "author": {
+                    "givenName": "John",
+                    "familyName": "Doe"
+                },
+                "tags": [
+                    "example",
+                    "sample"
+                ],
+                "content": "This will be unchanged"
+            })"_json;
+
+            json expected = R"({
+                "title": "Hello!",
+                "author": {
+                    "givenName": "John"
+                },
+                "tags": [
+                    "example"
+                ],
+                "content": "This will be unchanged",
+                "phoneNumber": "+01-123-456-7890"
+            })"_json;
+
+            document.merge_patch(json::merge_diff(document, expected));
+            CHECK(document == expected);
+        }
+
+        SECTION("Appendix A")
+        {
+            SECTION("Example 1")
+            {
+                json original = R"({"a":"b"})"_json;
+                json result = R"({"a":"c"})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 2")
+            {
+                json original = R"({"a":"b"})"_json;
+                json result = R"({"a":"b", "b":"c"})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 3")
+            {
+                json original = R"({"a":"b"})"_json;
+                json result = R"({})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 4")
+            {
+                json original = R"({"a":"b","b":"c"})"_json;
+                json result = R"({"b":"c"})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 5")
+            {
+                json original = R"({"a":["b"]})"_json;
+                json result = R"({"a":"c"})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 6")
+            {
+                json original = R"({"a":"c"})"_json;
+                json result = R"({"a":["b"]})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 7")
+            {
+                json original = R"({"a":{"b": "c"}})"_json;
+                json result = R"({"a": {"b": "d"}})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 8")
+            {
+                json original = R"({"a":[{"b":"c"}]})"_json;
+                json result = R"({"a":[1]})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 9")
+            {
+                json original = R"(["a","b"])"_json;
+                json result = R"(["c","d"])"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 10")
+            {
+                json original = R"({"a":"b"})"_json;
+                json result = R"(["c"])"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 11")
+            {
+                json original = R"({"a":"foo"})"_json;
+                json result = R"(null)"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 12")
+            {
+                json original = R"({"a":"foo"})"_json;
+                json result = R"("bar")"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 13")
+            {
+                json original = R"({"e":null})"_json;
+                json result = R"({"e":null,"a":1})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 14")
+            {
+                json original = R"([1,2])"_json;
+                json result = R"({"a":"b"})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+
+            SECTION("Example 15")
+            {
+                json original = R"({})"_json;
+                json result = R"({"a":{"bb":{}}})"_json;
+
+                original.merge_patch(json::merge_diff(original, result));
+                CHECK(original == result);
+            }
+        }
+    }
+
+    SECTION("null values")
+    {
+        SECTION("object with null value to object")
+        {
+            json original = R"({"a":null})"_json;
+            json result = R"({"a":{"b":"c"}})"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+
+        SECTION("object to object with null value")
+        {
+            json original = R"({"a":{"b":"c"}})"_json;
+            json result = R"({"a":null})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"a\" to null", json::other_error&);
+        }
+
+        SECTION("primitive to object with null value")
+        {
+            json original = R"({"a":1})"_json;
+            json result   = R"({"a":null})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"a\" to null", json::other_error&);
+        }
+
+        SECTION("nested primitive to object with null value")
+        {
+            json original = R"({"a":{"b":1}})"_json;
+            json result   = R"({"a":{"b":null}})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"b\" to null", json::other_error&);
+        }
+
+        SECTION("array value to object with null value")
+        {
+            json original = R"({"a":[1,2]})"_json;
+            json result   = R"({"a":null})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"a\" to null", json::other_error&);
+        }
+
+        SECTION("nested object to object with null value")
+        {
+            json original = R"({"a":{"b":{"c":"d"}}})"_json;
+            json result   = R"({"a":{"b":null}})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"b\" to null", json::other_error&);
+        }
+
+        SECTION("nested primitive to object with null value with sibling")
+        {
+            json original = R"({"x":"y","a":{"b":"c"}})"_json;
+            json result   = R"({"x":"y","a":{"b":null, "c":"d"}})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"b\" to null", json::other_error&);
+        }
+
+        SECTION("empty object to object with null value")
+        {
+            json original = R"({})"_json;
+            json result   = R"({"a":null})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"a\" to null", json::other_error&);
+        }
+
+        SECTION("null to object with null value")
+        {
+            json original = R"(null)"_json;
+            json result   = R"({"a":null})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"a\" to null", json::other_error&);
+        }
+
+        SECTION("array to object with null value")
+        {
+            json original = R"([])"_json;
+            json result   = R"({"a":null})"_json;
+
+            json _;
+            CHECK_THROWS_WITH_AS(_ = json::merge_diff(original, result), "[json.exception.other_error.503] cannot set \"a\" to null", json::other_error&);
+        }
+    }
+
+    SECTION("no change")
+    {
+        SECTION("object")
+        {
+            json original = R"({"a":"b","b":"c"})"_json;
+            json result   = R"({"a":"b","b":"c"})"_json;
+
+            auto patch = json::merge_diff(original, result);
+            CHECK(patch.empty());
+            original.merge_patch(patch);
+            CHECK(original == result);
+        }
+
+        SECTION("empty object")
+        {
+            json original = R"({})"_json;
+            json result   = R"({})"_json;
+
+            auto patch = json::merge_diff(original, result);
+            CHECK(patch.empty());
+            original.merge_patch(patch);
+            CHECK(original == result);
+        }
+
+        SECTION("array")
+        {
+            json original = R"([1,2,3])"_json;
+            json result   = R"([1,2,3])"_json;
+
+            auto patch = json::merge_diff(original, result);
+            CHECK(!patch.empty());
+            original.merge_patch(patch);
+            CHECK(original == result);
+        }
+
+        SECTION("null")
+        {
+            json original = R"(null)"_json;
+            json result   = R"(null)"_json;
+
+            auto patch = json::merge_diff(original, result);
+            CHECK(patch.empty());
+            original.merge_patch(patch);
+            CHECK(original == result);
+        }
+
+        SECTION("string")
+        {
+            json original = R"("ab")"_json;
+            json result   = R"("ab")"_json;
+
+            auto patch = json::merge_diff(original, result);
+            CHECK(!patch.empty());
+            original.merge_patch(patch);
+            CHECK(original == result);
+        }
+
+        SECTION("number")
+        {
+            json original = R"(42)"_json;
+            json result   = R"(42)"_json;
+
+            auto patch = json::merge_diff(original, result);
+            CHECK(!patch.empty());
+            original.merge_patch(patch);
+            CHECK(original == result);
+        }
+    }
+
+    SECTION("primitives")
+    {
+        SECTION("string")
+        {
+            json original = R"("a")"_json;
+            json result   = R"("b")"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+
+        SECTION("number")
+        {
+            json original = R"(1)"_json;
+            json result   = R"(2)"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+
+        SECTION("boolean")
+        {
+            json original = R"(false)"_json;
+            json result   = R"(true)"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+    }
+
+    SECTION("arrays")
+    {
+        SECTION("array to array")
+        {
+            json original = R"([1,2,3])"_json;
+            json result   = R"([1,2,4])"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+
+        SECTION("array to empty array")
+        {
+            json original = R"([1,2,3])"_json;
+            json result   = R"([])"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+
+        SECTION("empty array to array")
+        {
+            json original = R"([])"_json;
+            json result   = R"([1,2,3])"_json;
+
+            original.merge_patch(json::merge_diff(original, result));
+            CHECK(original == result);
+        }
+    }
+}