diff --git a/src/CSharp/EasyMicroservices.Cores.Clients/CoreContractResolver.cs b/src/CSharp/EasyMicroservices.Cores.Clients/CoreContractResolver.cs
new file mode 100644
index 0000000..717a874
--- /dev/null
+++ b/src/CSharp/EasyMicroservices.Cores.Clients/CoreContractResolver.cs
@@ -0,0 +1,25 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+using System.Reflection;
+
+namespace EasyMicroservices.Cores.Clients
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public class CoreContractResolver : DefaultContractResolver
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="member"></param>
+        /// <param name="memberSerialization"></param>
+        /// <returns></returns>
+        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
+        {
+            var jsonProp = base.CreateProperty(member, memberSerialization);
+            jsonProp.Required = Required.Default;
+            return jsonProp;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/CSharp/EasyMicroservices.Cores.Clients/CoreSerializerSettings.cs b/src/CSharp/EasyMicroservices.Cores.Clients/CoreSerializerSettings.cs
new file mode 100644
index 0000000..163a91e
--- /dev/null
+++ b/src/CSharp/EasyMicroservices.Cores.Clients/CoreSerializerSettings.cs
@@ -0,0 +1,19 @@
+using Newtonsoft.Json;
+
+namespace EasyMicroservices.Cores.Clients
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public class CoreSerializerSettings : JsonSerializerSettings
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="settings"></param>
+        public CoreSerializerSettings(JsonSerializerSettings settings)
+        {
+            this.ContractResolver = new CoreContractResolver();
+        }
+    }
+}
diff --git a/src/CSharp/EasyMicroservices.Cores.Clients/CoreSwaggerClientBase.cs b/src/CSharp/EasyMicroservices.Cores.Clients/CoreSwaggerClientBase.cs
new file mode 100644
index 0000000..41a9dcc
--- /dev/null
+++ b/src/CSharp/EasyMicroservices.Cores.Clients/CoreSwaggerClientBase.cs
@@ -0,0 +1,37 @@
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace EasyMicroservices.Cores.Clients
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public abstract class CoreSwaggerClientBase
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        public string BearerToken { get; private set; }
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="token"></param>
+        public void SetBearerToken(string token)
+        {
+            BearerToken = token;
+        }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="cancellationToken"></param>
+        /// <returns></returns>
+        protected Task<HttpRequestMessage> CreateHttpRequestMessageAsync(CancellationToken cancellationToken)
+        {
+            var msg = new HttpRequestMessage();
+            msg.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", BearerToken);
+            return Task.FromResult(msg);
+        }
+    }
+}
diff --git a/src/CSharp/EasyMicroservices.Cores.Clients/EasyMicroservices.Cores.Clients.csproj b/src/CSharp/EasyMicroservices.Cores.Clients/EasyMicroservices.Cores.Clients.csproj
new file mode 100644
index 0000000..6646008
--- /dev/null
+++ b/src/CSharp/EasyMicroservices.Cores.Clients/EasyMicroservices.Cores.Clients.csproj
@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>netstandard2.0;netstandard2.1;net6.0;net8.0</TargetFrameworks>
+    <Platforms>AnyCPU;x64;x86</Platforms>
+    <Authors>EasyMicroservices</Authors>
+    <Version>0.0.0.51</Version>
+    <Description>core of database.</Description>
+    <Copyright>EasyMicroservices@gmail.com</Copyright>
+    <PackageTags>core,cores,base,client,clients</PackageTags>
+    <PackageProjectUrl>https://github.com/EasyMicroservices/Cores</PackageProjectUrl>
+    <LangVersion>latest</LangVersion>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <DocumentationFile>.\bin\$(Configuration)\$(TargetFramework)\EasyMicroservices.Cores.Clients.xml</DocumentationFile>
+    <PackageReadmeFile>README.md</PackageReadmeFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+
+</Project>
diff --git a/src/CSharp/EasyMicroservices.Cores.sln b/src/CSharp/EasyMicroservices.Cores.sln
index 62c8995..f4ff4f4 100644
--- a/src/CSharp/EasyMicroservices.Cores.sln
+++ b/src/CSharp/EasyMicroservices.Cores.sln
@@ -23,9 +23,11 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Test-Layer", "Test-Layer",
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "EasyMicroservices.Cores.Relational.EntityFrameworkCore", "EasyMicroservices.Cores.Relational.EntityFrameworkCore\EasyMicroservices.Cores.Relational.EntityFrameworkCore.csproj", "{2B4DE46B-911F-4C08-B506-B8D31A8B074B}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EasyMicroservices.Cores.AspEntityFrameworkCoreApi", "EasyMicroservices.Cores.AspEntityFrameworkCoreApi\EasyMicroservices.Cores.AspEntityFrameworkCoreApi.csproj", "{2A012C31-966A-427B-B685-DCB95AC299E3}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "EasyMicroservices.Cores.AspEntityFrameworkCoreApi", "EasyMicroservices.Cores.AspEntityFrameworkCoreApi\EasyMicroservices.Cores.AspEntityFrameworkCoreApi.csproj", "{2A012C31-966A-427B-B685-DCB95AC299E3}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EasyMicroservices.Cores.AspCore.Tests", "EasyMicroservices.Cores.AspCore.Tests\EasyMicroservices.Cores.AspCore.Tests.csproj", "{243E15A6-5AD6-4304-8F91-D12666C59A0E}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "EasyMicroservices.Cores.AspCore.Tests", "EasyMicroservices.Cores.AspCore.Tests\EasyMicroservices.Cores.AspCore.Tests.csproj", "{243E15A6-5AD6-4304-8F91-D12666C59A0E}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EasyMicroservices.Cores.Clients", "EasyMicroservices.Cores.Clients\EasyMicroservices.Cores.Clients.csproj", "{1F65B13F-F101-437C-80E7-BA4B54574D5F}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -145,6 +147,18 @@ Global
 		{243E15A6-5AD6-4304-8F91-D12666C59A0E}.Release|x64.Build.0 = Release|Any CPU
 		{243E15A6-5AD6-4304-8F91-D12666C59A0E}.Release|x86.ActiveCfg = Release|Any CPU
 		{243E15A6-5AD6-4304-8F91-D12666C59A0E}.Release|x86.Build.0 = Release|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Debug|x64.Build.0 = Debug|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Debug|x86.Build.0 = Debug|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Release|x64.ActiveCfg = Release|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Release|x64.Build.0 = Release|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Release|x86.ActiveCfg = Release|Any CPU
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -159,6 +173,7 @@ Global
 		{2B4DE46B-911F-4C08-B506-B8D31A8B074B} = {B9CFFFCB-64BC-4E3A-982B-C50FEFE6EA9B}
 		{2A012C31-966A-427B-B685-DCB95AC299E3} = {5F639C59-EF1C-464B-85F1-FE01E4A9F81A}
 		{243E15A6-5AD6-4304-8F91-D12666C59A0E} = {C2D086CC-9E2B-4152-B8F7-81E91032C17C}
+		{1F65B13F-F101-437C-80E7-BA4B54574D5F} = {B9CFFFCB-64BC-4E3A-982B-C50FEFE6EA9B}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {0E8382C1-722C-4F92-B66F-0354487C7F02}