diff --git a/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeConverter.cs b/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeConverter.cs
index 79165843..da03fb5e 100644
--- a/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeConverter.cs
+++ b/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeConverter.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
@@ -31,5 +32,5 @@ public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, Jso
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
-        => writer.WriteStringValue(value.ToUniversalTime().ToString(format));
+        => writer.WriteStringValue(value.ToUniversalTime().ToString(format, CultureInfo.InvariantCulture));
 }
diff --git a/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeOffsetConverter.cs b/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeOffsetConverter.cs
index e5132446..7b25efeb 100644
--- a/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeOffsetConverter.cs
+++ b/src/CommunityToolkit.Datasync.Client/Serialization/DateTimeOffsetConverter.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
@@ -31,5 +32,5 @@ public override DateTimeOffset Read(ref Utf8JsonReader reader, Type typeToConver
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, DateTimeOffset value, JsonSerializerOptions options)
-        => writer.WriteStringValue(value.ToUniversalTime().UtcDateTime.ToString(format));
+        => writer.WriteStringValue(value.ToUniversalTime().UtcDateTime.ToString(format, CultureInfo.InvariantCulture));
 }
diff --git a/src/CommunityToolkit.Datasync.Client/Serialization/TimeOnlyConverter.cs b/src/CommunityToolkit.Datasync.Client/Serialization/TimeOnlyConverter.cs
index 6dafd78b..22a1396d 100644
--- a/src/CommunityToolkit.Datasync.Client/Serialization/TimeOnlyConverter.cs
+++ b/src/CommunityToolkit.Datasync.Client/Serialization/TimeOnlyConverter.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
@@ -31,5 +32,5 @@ public override TimeOnly Read(ref Utf8JsonReader reader, Type typeToConvert, Jso
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, TimeOnly value, JsonSerializerOptions options)
-        => writer.WriteStringValue(value.ToString(format));
+        => writer.WriteStringValue(value.ToString(format, CultureInfo.InvariantCulture));
 }
diff --git a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeConverter.cs b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeConverter.cs
index a33327a1..a61d41e7 100644
--- a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeConverter.cs
+++ b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeConverter.cs
@@ -15,7 +15,6 @@ namespace CommunityToolkit.Datasync.Server.Abstractions.Json;
 public class DateTimeConverter : JsonConverter<DateTime>
 {
     private const string format = "yyyy-MM-dd'T'HH:mm:ss.fffK";
-    private static readonly CultureInfo culture = new("en-US");
 
     /// <inheritdoc />
     public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
@@ -23,5 +22,5 @@ public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, Jso
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
-        => writer.WriteStringValue(value.ToUniversalTime().ToString(format, culture));
+        => writer.WriteStringValue(value.ToUniversalTime().ToString(format, CultureInfo.InvariantCulture));
 }
diff --git a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeOffsetConverter.cs b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeOffsetConverter.cs
index 08ea9564..5bf210bd 100644
--- a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeOffsetConverter.cs
+++ b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeOffsetConverter.cs
@@ -15,7 +15,6 @@ namespace CommunityToolkit.Datasync.Server.Abstractions.Json;
 public class DateTimeOffsetConverter : JsonConverter<DateTimeOffset>
 {
     private const string format = "yyyy-MM-dd'T'HH:mm:ss.fffK";
-    private static readonly CultureInfo culture = new("en-US");
 
     /// <inheritdoc />
     public override DateTimeOffset Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
@@ -23,5 +22,5 @@ public override DateTimeOffset Read(ref Utf8JsonReader reader, Type typeToConver
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, DateTimeOffset value, JsonSerializerOptions options)
-        => writer.WriteStringValue(value.ToUniversalTime().UtcDateTime.ToString(format, culture));
+        => writer.WriteStringValue(value.ToUniversalTime().UtcDateTime.ToString(format, CultureInfo.InvariantCulture));
 }
diff --git a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/JsonExtensions.cs b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/JsonExtensions.cs
index abc33dd8..8b96f82d 100644
--- a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/JsonExtensions.cs
+++ b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/JsonExtensions.cs
@@ -17,7 +17,7 @@ internal static class JsonExtensions
     /// <param name="reader">The <see cref="Utf8JsonReader"/> to assert.</param>
     /// <param name="expectedTokenType">The expected <see cref="JsonTokenType"/> of the current token.</param>
     /// <exception cref="JsonException">The current token did not match the <paramref name="expectedTokenType"/>.</exception>
-    public static void Expect(in this Utf8JsonReader reader, JsonTokenType expectedTokenType)
+    public static void Expect(this Utf8JsonReader reader, JsonTokenType expectedTokenType)
     {
         if (reader.TokenType != expectedTokenType)
         {
diff --git a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/TimeOnlyConverter.cs b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/TimeOnlyConverter.cs
index 2124e666..b7218782 100644
--- a/src/CommunityToolkit.Datasync.Server.Abstractions/Json/TimeOnlyConverter.cs
+++ b/src/CommunityToolkit.Datasync.Server.Abstractions/Json/TimeOnlyConverter.cs
@@ -15,7 +15,6 @@ namespace CommunityToolkit.Datasync.Server.Abstractions.Json;
 public class TimeOnlyConverter : JsonConverter<TimeOnly>
 {
     private const string format = "HH:mm:ss.fff";
-    private static readonly CultureInfo culture = new("en-US");
 
     /// <inheritdoc />
     public override TimeOnly Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
@@ -23,5 +22,5 @@ public override TimeOnly Read(ref Utf8JsonReader reader, Type typeToConvert, Jso
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, TimeOnly value, JsonSerializerOptions options)
-        => writer.WriteStringValue(value.ToString(format, culture));
+        => writer.WriteStringValue(value.ToString(format, CultureInfo.InvariantCulture));
 }
diff --git a/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncDocumentFilter.cs b/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncDocumentFilter.cs
index f24193de..0d4f9561 100644
--- a/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncDocumentFilter.cs
+++ b/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncDocumentFilter.cs
@@ -112,6 +112,7 @@ internal void ProcessController(Type entityType, string routePath, OpenApiDocume
                 case OpType.Create:
                     // Request Edits
                     operation.Value.AddConditionalHeader(true);
+                    operation.Value.AddRequestWithContent(context.SchemaRepository.Schemas[entityType.Name]);
 
                     // Response Edits
                     operation.Value.AddResponseWithContent("201", "Created", context.SchemaRepository.Schemas[entityType.Name]);
@@ -152,6 +153,7 @@ internal void ProcessController(Type entityType, string routePath, OpenApiDocume
                 case OpType.Replace:
                     // Request Edits
                     operation.Value.AddConditionalHeader();
+                    operation.Value.AddRequestWithContent(context.SchemaRepository.Schemas[entityType.Name]);
 
                     // Response Edits
                     operation.Value.AddResponseWithContent("200", "OK", context.SchemaRepository.Schemas[entityType.Name]);
diff --git a/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncOperationExtensions.cs b/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncOperationExtensions.cs
index e6dcbc4b..caed0448 100644
--- a/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncOperationExtensions.cs
+++ b/src/CommunityToolkit.Datasync.Server.Swashbuckle/DatasyncOperationExtensions.cs
@@ -95,6 +95,24 @@ internal static void AddResponseWithContent(this OpenApiOperation operation, str
         });
         operation.Responses[statusCode] = response;
     }
+    /// <summary>
+    /// Adds the content type and schema to the request body.
+    /// </summary>
+    /// <param name="operation">The <see cref="OpenApiOperation"/> to modify.</param>
+    /// <param name="schema">The schema of the entity in the request.</param>
+    internal static void AddRequestWithContent(this OpenApiOperation operation, OpenApiSchema schema)
+    {
+        operation.RequestBody = new OpenApiRequestBody
+        {
+            Content = new Dictionary<string, OpenApiMediaType>
+            {
+                [JsonMediaType] = new OpenApiMediaType()
+                {
+                    Schema = schema
+                }
+            }
+        };
+    }
 
     /// <summary>
     /// Adds or replaces the 409/412 Conflict/Precondition Failed response.
diff --git a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeConverter_Tests.cs b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeConverter_Tests.cs
index bd185225..213ed3a9 100644
--- a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeConverter_Tests.cs
+++ b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeConverter_Tests.cs
@@ -2,40 +2,84 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using CommunityToolkit.Datasync.Client.Serialization;
 using System.Text.Json;
 
 namespace CommunityToolkit.Datasync.Client.Test.Serialization;
 
 [ExcludeFromCodeCoverage]
-public class DateTimeConverter_Tests
+public class DateTimeConverter_Tests : SerializerTests
 {
-    private readonly JsonSerializerOptions serializerOptions;
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_ReadsJson(string culture)
+    {
+        const string json = """{"updatedAt":"2021-08-21T12:30:15.123+00:00"}""";
+        DateTime value = new(2021, 8, 21, 12, 30, 15, 123, DateTimeKind.Utc);
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+            // Use FileTime comparison because no FluentAssertions support for DateTime ignoring zone info.
+            entity.UpdatedAt.ToFileTime().Should().Be(value.ToFileTime());
+        });
+    }
 
-    public DateTimeConverter_Tests()
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_WritesJson(string culture)
     {
-        this.serializerOptions = new JsonSerializerOptions(JsonSerializerDefaults.Web);
-        this.serializerOptions.Converters.Add(new DateTimeConverter());
+        const string json = """{"updatedAt":"2021-08-21T12:30:15.123Z"}""";
+        DateTime value = new(2021, 8, 21, 12, 30, 15, 123, 456, DateTimeKind.Utc);
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = new() { UpdatedAt = value };
+            string actual = JsonSerializer.Serialize(entity, SerializerOptions);
+            Assert.Equal(json, actual);
+        });
     }
 
-    [Fact]
-    public void Read_Null_Works()
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_WritesJson_WithTimeZone(string culture)
     {
-        string json = """{"dt":null}""";
-        SUT actual = JsonSerializer.Deserialize<SUT>(json, this.serializerOptions);
-        actual.dt.Should().Be(DateTime.MinValue);
+        const string json = """{"updatedAt":"2021-08-21T12:30:15.123Z"}""";
+        DateTime value = DateTime.Parse("2021-08-21T20:30:15.1234567+08:00");
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = new() { UpdatedAt = value };
+            string actual = JsonSerializer.Serialize(entity, SerializerOptions);
+            Assert.Equal(json, actual);
+        });
     }
 
     [Fact]
-    public void Read_Int_Throws()
+    public void Converter_ThrowsOnBadDateInInput()
     {
-        string json = """{"dt":42}""";
-        Action act = () => _ = JsonSerializer.Deserialize<SUT>(json, this.serializerOptions);
-        act.Should().Throw<JsonException>();
+        const string json = """{"updatedAt":"foo"}""";
+        Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+        act.Should().Throw<FormatException>();
+    }
+
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_HandlesNullDateInInput(string culture)
+    {
+        const string json = """{"updatedAt":null}""";
+        DateTime value = DateTime.MinValue;
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+            entity.UpdatedAt.Should().Be(value);
+        });
     }
 
-    class SUT
+    #region Models
+    public class Entity
     {
-        public DateTime dt { get; set; }
+        public DateTime UpdatedAt { get; set; }
     }
+    #endregion
 }
diff --git a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeOffsetConverter_Tests.cs b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeOffsetConverter_Tests.cs
index 81172977..71881f99 100644
--- a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeOffsetConverter_Tests.cs
+++ b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/DateTimeOffsetConverter_Tests.cs
@@ -2,40 +2,84 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using CommunityToolkit.Datasync.Client.Serialization;
 using System.Text.Json;
+using System.Text.RegularExpressions;
 
 namespace CommunityToolkit.Datasync.Client.Test.Serialization;
 
 [ExcludeFromCodeCoverage]
-public class DateTimeOffsetConverter_Tests
+public class DateTimeOffsetConverter_Tests : SerializerTests
 {
-    private readonly JsonSerializerOptions serializerOptions;
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_ReadsJson(string culture)
+    {
+        const string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123+00:00\"}";
+        DateTimeOffset value = new(2021, 8, 21, 12, 30, 15, 123, TimeSpan.Zero);
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+            entity.UpdatedAt.Should().Be(value);
+        });
+    }
 
-    public DateTimeOffsetConverter_Tests()
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_WritesJson(string culture)
     {
-        this.serializerOptions = new JsonSerializerOptions(JsonSerializerDefaults.Web);
-        this.serializerOptions.Converters.Add(new DateTimeOffsetConverter());
+        const string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123Z\"}";
+        DateTimeOffset value = new(2021, 8, 21, 12, 30, 15, 123, 456, TimeSpan.Zero);
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = new() { UpdatedAt = value };
+            string actual = JsonSerializer.Serialize(entity, SerializerOptions);
+            Assert.Equal(json, actual);
+        });
     }
 
-    [Fact]
-    public void Read_Null_Works()
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_WritesJson_WithTimeZone(string culture)
     {
-        string json = """{"dt":null}""";
-        SUT actual = JsonSerializer.Deserialize<SUT>(json, this.serializerOptions);
-        actual.dt.Should().Be(DateTimeOffset.MinValue);
+        const string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123Z\"}";
+        DateTimeOffset value = new(2021, 8, 21, 20, 30, 15, 123, 456, TimeSpan.FromHours(8));
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = new() { UpdatedAt = value };
+            string actual = JsonSerializer.Serialize(entity, SerializerOptions);
+            Assert.Equal(json, actual);
+        });
     }
 
     [Fact]
-    public void Read_Int_Throws()
+    public void Converter_ThrowsOnBadDateInInput()
     {
-        string json = """{"dt":42}""";
-        Action act = () => _ = JsonSerializer.Deserialize<SUT>(json, this.serializerOptions);
-        act.Should().Throw<JsonException>();
+        const string json = "{\"updatedAt\":\"foo\"}";
+        Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+        act.Should().Throw<Exception>();
+    }
+
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_HandlesNullDateInInput(string culture)
+    {
+        const string json = """{"updatedAt":null}""";
+        DateTimeOffset value = DateTimeOffset.MinValue;
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+            entity.UpdatedAt.Should().Be(value);
+        });
     }
 
-    class SUT
+    #region Models
+    public class Entity
     {
-        public DateTimeOffset dt { get; set; }
+        public DateTimeOffset UpdatedAt { get; set; }
     }
-}
+    #endregion
+}
\ No newline at end of file
diff --git a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/SerializerTests.cs b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/SerializerTests.cs
new file mode 100644
index 00000000..0ccf246f
--- /dev/null
+++ b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/SerializerTests.cs
@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using CommunityToolkit.Datasync.Client.Serialization;
+using System.Globalization;
+using System.Text.Json;
+
+#pragma warning disable IDE0028 // Simplify collection initialization
+
+namespace CommunityToolkit.Datasync.Client.Test.Serialization;
+
+[ExcludeFromCodeCoverage]
+public abstract class SerializerTests
+{
+    protected static JsonSerializerOptions SerializerOptions
+        => DatasyncSerializer.JsonSerializerOptions;
+
+    public static TheoryData<string> Locales => new()
+    {
+        "fr-FR",
+        "da-DA",
+        "en-US"
+    };
+
+    protected static void TestWithCulture(string culture, Action act)
+    {
+        CultureInfo currentCulture = Thread.CurrentThread.CurrentCulture;
+        Thread.CurrentThread.CurrentCulture = new CultureInfo(culture);
+        try
+        {
+            act.Invoke();
+        }
+        finally
+        {
+            Thread.CurrentThread.CurrentCulture = currentCulture;
+        }
+    }
+}
diff --git a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/TimeOnlyConverter_Tests.cs b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/TimeOnlyConverter_Tests.cs
index 39928bc0..63360c4b 100644
--- a/tests/CommunityToolkit.Datasync.Client.Test/Serialization/TimeOnlyConverter_Tests.cs
+++ b/tests/CommunityToolkit.Datasync.Client.Test/Serialization/TimeOnlyConverter_Tests.cs
@@ -2,40 +2,69 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using CommunityToolkit.Datasync.Client.Serialization;
 using System.Text.Json;
+using System.Text.RegularExpressions;
 
 namespace CommunityToolkit.Datasync.Client.Test.Serialization;
 
 [ExcludeFromCodeCoverage]
-public class TimeOnlyConverter_Tests
+public class TimeOnlyConverter_Tests : SerializerTests
 {
-    private readonly JsonSerializerOptions serializerOptions;
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_ReadsJson(string culture)
+    {
+        const string json = """{"updatedAt":"12:30:15.123"}""";
+        TimeOnly value = new(12, 30, 15, 123);
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+            entity.UpdatedAt.Ticks.Should().Be(value.Ticks);
+        });
+    }
 
-    public TimeOnlyConverter_Tests()
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_WritesJson(string culture)
     {
-        this.serializerOptions = new JsonSerializerOptions(JsonSerializerDefaults.Web);
-        this.serializerOptions.Converters.Add(new TimeOnlyConverter());
+        const string json = """{"updatedAt":"12:30:15.123"}""";
+        TimeOnly value = new(12, 30, 15, 123, 456);
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = new() { UpdatedAt = value };
+            string actual = JsonSerializer.Serialize(entity, SerializerOptions);
+            Assert.Equal(json, actual);
+        });
     }
 
     [Fact]
-    public void Read_Null_Works()
+    public void Converter_ThrowsOnBadDateInInput()
     {
-        string json = """{"dt":null}""";
-        SUT actual = JsonSerializer.Deserialize<SUT>(json, this.serializerOptions);
-        actual.dt.Should().Be(TimeOnly.MinValue);
+        const string json = """{"updatedAt":"foo"}""";
+        Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+        act.Should().Throw<FormatException>();
     }
 
-    [Fact]
-    public void Read_Int_Throws()
+    [Theory]
+    [MemberData(nameof(Locales))]
+    public void Converter_HandlesNullDateInInput(string culture)
     {
-        string json = """{"dt":42}""";
-        Action act = () => _ = JsonSerializer.Deserialize<SUT>(json, this.serializerOptions);
-        act.Should().Throw<JsonException>();
+        const string json = """{"updatedAt":null}""";
+        TimeOnly value = TimeOnly.MinValue;
+
+        TestWithCulture(culture, () =>
+        {
+            Entity entity = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
+            entity.UpdatedAt.Ticks.Should().Be(value.Ticks);
+        });
     }
 
-    class SUT
+    #region Models
+    public class Entity
     {
-        public TimeOnly dt { get; set; }
+        public TimeOnly UpdatedAt { get; set; }
     }
+    #endregion
 }
diff --git a/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeConverter_Tests.cs b/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeConverter_Tests.cs
index 8819bb07..e40b6814 100644
--- a/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeConverter_Tests.cs
+++ b/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeConverter_Tests.cs
@@ -13,7 +13,7 @@ public class DateTimeConverter_Tests : SerializerTests
     [MemberData(nameof(Locales))]
     public void Converter_ReadsJson(string culture)
     {
-        string json = """{"updatedAt":"2021-08-21T12:30:15.123+00:00"}""";
+        const string json = """{"updatedAt":"2021-08-21T12:30:15.123+00:00"}""";
         DateTime value = new(2021, 8, 21, 12, 30, 15, 123, DateTimeKind.Utc);
 
         TestWithCulture(culture, () =>
@@ -27,7 +27,7 @@ public void Converter_ReadsJson(string culture)
     [MemberData(nameof(Locales))]
     public void Converter_WritesJson(string culture)
     {
-        string json = """{"updatedAt":"2021-08-21T12:30:15.123Z"}""";
+        const string json = """{"updatedAt":"2021-08-21T12:30:15.123Z"}""";
         DateTime value = new(2021, 8, 21, 12, 30, 15, 123, 456, DateTimeKind.Utc);
 
         TestWithCulture(culture, () =>
@@ -42,7 +42,7 @@ public void Converter_WritesJson(string culture)
     [MemberData(nameof(Locales))]
     public void Converter_WritesJson_WithTimeZone(string culture)
     {
-        string json = """{"updatedAt":"2021-08-21T12:30:15.123Z"}""";
+        const string json = """{"updatedAt":"2021-08-21T12:30:15.123Z"}""";
         DateTime value = DateTime.Parse("2021-08-21T20:30:15.1234567+08:00");
 
         TestWithCulture(culture, () =>
@@ -56,7 +56,7 @@ public void Converter_WritesJson_WithTimeZone(string culture)
     [Fact]
     public void Converter_ThrowsOnBadDateInInput()
     {
-        string json = """{"updatedAt":"foo"}""";
+        const string json = """{"updatedAt":"foo"}""";
         Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
         act.Should().Throw<FormatException>();
     }
@@ -64,7 +64,7 @@ public void Converter_ThrowsOnBadDateInInput()
     [Fact]
     public void Converter_ThrowsOnNullDateInInput()
     {
-        string json = """{"updatedAt":null}""";
+        const string json = """{"updatedAt":null}""";
         Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
         act.Should().Throw<FormatException>();
     }
diff --git a/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeOffsetConverter_Tests.cs b/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeOffsetConverter_Tests.cs
index 39e4e372..dbc47ce5 100644
--- a/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeOffsetConverter_Tests.cs
+++ b/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/DateTimeOffsetConverter_Tests.cs
@@ -13,7 +13,7 @@ public class DateTimeOffsetConverter_Tests : SerializerTests
     [MemberData(nameof(Locales))]
     public void Converter_ReadsJson(string culture)
     {
-        string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123+00:00\"}";
+        const string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123+00:00\"}";
         DateTimeOffset value = new(2021, 8, 21, 12, 30, 15, 123, TimeSpan.Zero);
 
         TestWithCulture(culture, () =>
@@ -27,7 +27,7 @@ public void Converter_ReadsJson(string culture)
     [MemberData(nameof(Locales))]
     public void Converter_WritesJson(string culture)
     {
-        string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123Z\"}";
+        const string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123Z\"}";
         DateTimeOffset value = new(2021, 8, 21, 12, 30, 15, 123, 456, TimeSpan.Zero);
 
         TestWithCulture(culture, () =>
@@ -42,7 +42,7 @@ public void Converter_WritesJson(string culture)
     [MemberData(nameof(Locales))]
     public void Converter_WritesJson_WithTimeZone(string culture)
     {
-        string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123Z\"}";
+        const string json = "{\"updatedAt\":\"2021-08-21T12:30:15.123Z\"}";
         DateTimeOffset value = new(2021, 8, 21, 20, 30, 15, 123, 456, TimeSpan.FromHours(8));
 
         TestWithCulture(culture, () =>
@@ -56,7 +56,7 @@ public void Converter_WritesJson_WithTimeZone(string culture)
     [Fact]
     public void Converter_ThrowsOnBadDateInInput()
     {
-        string json = "{\"updatedAt\":\"foo\"}";
+        const string json = "{\"updatedAt\":\"foo\"}";
         Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
         act.Should().Throw<Exception>();
     }
@@ -64,7 +64,7 @@ public void Converter_ThrowsOnBadDateInInput()
     [Fact]
     public void Converter_ThrowsOnNullDateInInput()
     {
-        string json = """{"updatedAt":null}""";
+        const string json = """{"updatedAt":null}""";
         Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
         act.Should().Throw<FormatException>();
     }
diff --git a/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/TimeOnlyConverter_Tests.cs b/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/TimeOnlyConverter_Tests.cs
index f0a4e7f3..81e2930c 100644
--- a/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/TimeOnlyConverter_Tests.cs
+++ b/tests/CommunityToolkit.Datasync.Server.Abstractions.Test/Json/TimeOnlyConverter_Tests.cs
@@ -13,7 +13,7 @@ public class TimeOnlyConverter_Tests : SerializerTests
     [MemberData(nameof(Locales))]
     public void Converter_ReadsJson(string culture)
     {
-        string json = """{"updatedAt":"12:30:15.123"}""";
+        const string json = """{"updatedAt":"12:30:15.123"}""";
         TimeOnly value = new(12, 30, 15, 123);
 
         TestWithCulture(culture, () =>
@@ -27,7 +27,7 @@ public void Converter_ReadsJson(string culture)
     [MemberData(nameof(Locales))]
     public void Converter_WritesJson(string culture)
     {
-        string json = """{"updatedAt":"12:30:15.123"}""";
+        const string json = """{"updatedAt":"12:30:15.123"}""";
         TimeOnly value = new(12, 30, 15, 123, 456);
 
         TestWithCulture(culture, () =>
@@ -41,7 +41,7 @@ public void Converter_WritesJson(string culture)
     [Fact]
     public void Converter_ThrowsOnBadDateInInput()
     {
-        string json = """{"updatedAt":"foo"}""";
+        const string json = """{"updatedAt":"foo"}""";
         Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
         act.Should().Throw<FormatException>();
     }
@@ -49,7 +49,7 @@ public void Converter_ThrowsOnBadDateInInput()
     [Fact]
     public void Converter_ThrowsOnNullDateInInput()
     {
-        string json = """{"updatedAt":null}""";
+        const string json = """{"updatedAt":null}""";
         Action act = () => _ = JsonSerializer.Deserialize<Entity>(json, SerializerOptions);
         act.Should().Throw<FormatException>();
     }
diff --git a/tests/CommunityToolkit.Datasync.Server.Swashbuckle.Test/swagger.json b/tests/CommunityToolkit.Datasync.Server.Swashbuckle.Test/swagger.json
index 59c886ba..7623daf6 100644
--- a/tests/CommunityToolkit.Datasync.Server.Swashbuckle.Test/swagger.json
+++ b/tests/CommunityToolkit.Datasync.Server.Swashbuckle.Test/swagger.json
@@ -159,6 +159,15 @@
             }
           }
         ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/KitchenSink"
+              }
+            }
+          }
+        },
         "responses": {
           "201": {
             "description": "Created",
@@ -448,6 +457,15 @@
             }
           }
         ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/KitchenSink"
+              }
+            }
+          }
+        },
         "responses": {
           "200": {
             "description": "OK",
@@ -530,6 +548,15 @@
             }
           }
         ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/TodoItem"
+              }
+            }
+          }
+        },
         "responses": {
           "201": {
             "description": "Created",
@@ -819,6 +846,15 @@
             }
           }
         ],
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/TodoItem"
+              }
+            }
+          }
+        },
         "responses": {
           "200": {
             "description": "OK",