diff --git a/HackMD.API/HackMD.API.csproj b/HackMD.API/HackMD.API.csproj
index 9a41e29..c3092cd 100644
--- a/HackMD.API/HackMD.API.csproj
+++ b/HackMD.API/HackMD.API.csproj
@@ -17,4 +17,8 @@ https://github.com/isdaviddong/HackMD.API</Description>
     <RepositoryUrl>https://github.com/isdaviddong/HackMD.API</RepositoryUrl>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="3.1.10" />
+  </ItemGroup>
+
 </Project>
diff --git a/HackMD.API/HackMDClinet.cs b/HackMD.API/HackMDClinet.cs
index c97f8a1..dbb4a0b 100644
--- a/HackMD.API/HackMDClinet.cs
+++ b/HackMD.API/HackMDClinet.cs
@@ -1,6 +1,10 @@
 using System;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
 
 namespace HackMD.API
 {
@@ -8,85 +12,113 @@ public class HackMDClient
     {
         private string token;
 
-        public string Token
+        private static readonly Lazy<SocketsHttpHandler> s_socketLazy = new Lazy<SocketsHttpHandler>(() =>
         {
-            get { return token; }
-            set { token = value; }
-        }
+            var socketsHandler = new SocketsHttpHandler
+            {
+                PooledConnectionLifetime = TimeSpan.FromMinutes(10),
+                PooledConnectionIdleTimeout = TimeSpan.FromMinutes(5),
+                MaxConnectionsPerServer = 10
+            };
+            return socketsHandler;
+        });
+
+        private readonly string _token;
 
         public HackMDClient(string token)
         {
-            this.Token = token;
+            this._token = token;
+        }
+
+        static HttpClient CreateHttpClient(string token)
+        {
+            return new HttpClient(s_socketLazy.Value)
+            {
+                DefaultRequestHeaders =
+                {
+                    Authorization = new AuthenticationHeaderValue(JwtBearerDefaults.AuthenticationScheme,
+                        token)
+                },
+                BaseAddress = new Uri("https://api.hackmd.io/v1/")
+            };
         }
 
-        private string endpoint = "https://api.hackmd.io/v1/";
         #region "User API"
-        public User GetUserInformation()
+
+        public User GetUserInformation() => this.GetUserInformationAsync().Result;
+
+        public async Task<User> GetUserInformationAsync(CancellationToken cancel = default)
         {
-            HttpClient client = new HttpClient();
-            string uri = endpoint + $"/me";
-
-            // Request headers.
-            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {this.Token}");
-            var response = client.GetAsync(uri).Result;
-            var ResponseBody = response.Content.ReadAsStringAsync().Result;
-            var UserObj = System.Text.Json.JsonSerializer.Deserialize<User>(ResponseBody);
-            return UserObj;
+            var client = CreateHttpClient(this._token);
+            string uri = "me";
+
+            var request = CreateDefaultHttpRequest(token, uri);
+            var response = await client.SendAsync(request, cancel);
+            var responseBody = await response.Content.ReadAsStringAsync();
+            var result = System.Text.Json.JsonSerializer.Deserialize<User>(responseBody);
+            return result;
         }
+
         #endregion
 
         #region "User Notes API"
+
         /// <summary>
         /// Create a note
         /// </summary>
         /// <param name="newHackMDNote"></param>
         /// <returns></returns>
-        public NoteResponse CreateNote(Note newHackMDNote)
+        public NoteResponse CreateNote(Note newHackMDNote) => this.CreateNoteAsync(newHackMDNote).Result;
+
+        public async Task<NoteResponse> CreateNoteAsync(Note newHackMDNote, CancellationToken cancel = default)
         {
-            HttpClient client = new HttpClient();
-            string uri = endpoint + "/notes";
+            var client = CreateHttpClient(this._token);
+            string uri = "notes";
+
+            var requestBody = System.Text.Json.JsonSerializer.Serialize(newHackMDNote);
+            var requestContent = new StringContent(requestBody, Encoding.UTF8, "application/json");
 
-            // Request headers.
-            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {this.Token}");
-            var JSON = System.Text.Json.JsonSerializer.Serialize(newHackMDNote);
-            var content = new StringContent(JSON, Encoding.UTF8, "application/json");
             // Asynchronously call the REST API method.
-            var response = client.PostAsync(uri, content).Result;
-            var ResponseBody = response.Content.ReadAsStringAsync().Result;
-            var CreateNoteResponseObj = System.Text.Json.JsonSerializer.Deserialize<NoteResponse>(ResponseBody);
-            return CreateNoteResponseObj;
+            var response = await client.PostAsync(uri, requestContent, cancel);
+            var responseBody = await response.Content.ReadAsStringAsync();
+            var result = System.Text.Json.JsonSerializer.Deserialize<NoteResponse>(responseBody);
+            return result;
         }
-        public NoteResponse GetNote(string noteId)
+
+        public NoteResponse GetNote(string noteId) => this.GetNoteAsync(noteId).Result;
+
+        public async Task<NoteResponse> GetNoteAsync(string noteId)
         {
-            HttpClient client = new HttpClient();
-            string uri = endpoint + $"/notes/{noteId}";
-
-            // Request headers.
-            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {this.Token}");
-            var response = client.GetAsync(uri).Result;
-            var ResponseBody = response.Content.ReadAsStringAsync().Result;
-            var CreateNoteResponseObj = System.Text.Json.JsonSerializer.Deserialize<NoteResponse>(ResponseBody);
-            return CreateNoteResponseObj;
+            var client = CreateHttpClient(this._token);
+            string uri = $"notes/{noteId}";
+
+            var response = await client.GetAsync(uri);
+            var responseBody = await response.Content.ReadAsStringAsync();
+            var result = System.Text.Json.JsonSerializer.Deserialize<NoteResponse>(responseBody);
+            return result;
         }
-        public bool UpdateNote(string noteId, string content, ReadWritePermission readPermission, ReadWritePermission writePermission, string permalink)
+
+        public bool UpdateNote(string noteId, string content, ReadWritePermission readPermission,
+            ReadWritePermission writePermission, string permalink) =>
+            this.UpdateNoteAsync(noteId, content, readPermission, writePermission, permalink).Result;
+
+        public async Task<bool> UpdateNoteAsync(string noteId, string content, ReadWritePermission readPermission,
+            ReadWritePermission writePermission, string permalink)
         {
-            HttpClient client = new HttpClient();
-            string uri = endpoint + $"/notes/{noteId}";
+            var client = CreateHttpClient(this._token);
+
+            string uri = $"notes/{noteId}";
 
-            var obj = new
+            var requestBody = System.Text.Json.JsonSerializer.Serialize(new
             {
-                content = content,
+                content,
                 readPermission = readPermission.ToString(),
                 writePermission = writePermission.ToString(),
-                permalink = permalink
-            };
-
-            // Request headers.
-            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {this.Token}");
-            var JSON = System.Text.Json.JsonSerializer.Serialize(obj);
-            var body = new StringContent(JSON, Encoding.UTF8, "application/json");
-            var response = client.PatchAsync(uri, body).Result;
-            var ResponseBody = response.Content.ReadAsStringAsync().Result;
+                permalink
+            });
+            var requestContent = new StringContent(requestBody, Encoding.UTF8, "application/json");
+            var response = await client.PatchAsync(uri, requestContent);
+            var responseBody = await response.Content.ReadAsStringAsync();
             return response.StatusCode == System.Net.HttpStatusCode.Accepted;
         }
 
@@ -95,17 +127,25 @@ public bool UpdateNote(string noteId, string content, ReadWritePermission readPe
         /// </summary>
         /// <param name="noteId"></param>
         /// <returns></returns>
-        public bool DeleteNote(string noteId)
+        public bool DeleteNote(string noteId) => this.DeleteNoteAsync(noteId).Result;
+
+        public async Task<bool> DeleteNoteAsync(string noteId)
         {
-            HttpClient client = new HttpClient();
-            string uri = endpoint + $"/notes/{noteId}";
+            var client = CreateHttpClient(this._token);
 
-            // Request headers.
-            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {this.Token}");
+            string uri = $"notes/{noteId}";
 
-            var response = client.DeleteAsync(uri).Result;
+            var response = await client.DeleteAsync(uri);
             return response.StatusCode == System.Net.HttpStatusCode.NoContent;
         }
+
         #endregion
+
+        private static HttpRequestMessage CreateDefaultHttpRequest(string token, string uri)
+        {
+            var request = new HttpRequestMessage(HttpMethod.Get, uri);
+            request.Headers.Add("Authorization", $"Bearer {token}");
+            return request;
+        }
     }
-}
+}
\ No newline at end of file
diff --git a/HackMD.APITests/HackMDClinetTests.cs b/HackMD.APITests/HackMDClinetTests.cs
index 266bf52..df38f2c 100644
--- a/HackMD.APITests/HackMDClinetTests.cs
+++ b/HackMD.APITests/HackMDClinetTests.cs
@@ -1,8 +1,5 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using HackMD.API;
 using System;
-using System.Collections.Generic;
-using System.Text;
 
 namespace HackMD.API.Tests
 {
@@ -25,7 +22,7 @@ public HackMDClientTests()
         public void CreateNoteTest()
         {
             // 建立HackMDClient 物件
-            HackMDClient c = new HackMDClient(token); //須提供token
+            HackMDClient c = new HackMDClient(this.token); //須提供token
             //建立新 Note
             var ret = c.CreateNote(
                 new Note()
@@ -39,14 +36,14 @@ public void CreateNoteTest()
             //取得 NoteId
             TempNoteId = ret.id;
             Assert.IsTrue(!string.IsNullOrEmpty(ret.id));
-            //c.DeleteNote(ret.id);
+            // c.DeleteNote(ret.id);
         }
 
         [TestMethod()]
         public void DeleteNoteTest()
         {
             // 建立HackMDClient 物件
-            HackMDClient c = new HackMDClient(token); //須提供token
+            HackMDClient c = new HackMDClient(this.token); //須提供token
             var ret = c.CreateNote(
              new Note()
              {
@@ -67,7 +64,7 @@ public void DeleteNoteTest()
         public void UpdateNoteTest()
         {
             // 建立HackMDClient 物件
-            HackMDClient c = new HackMDClient(token); //須提供token
+            HackMDClient c = new HackMDClient(this.token); //須提供token
             var ret = c.CreateNote(
                new Note()
                {
@@ -94,7 +91,7 @@ public void UpdateNoteTest()
         public void GetNoteTest()
         {
             // 建立HackMDClient 物件
-            HackMDClient c = new HackMDClient(token); //須提供token
+            HackMDClient c = new HackMDClient(this.token); //須提供token
             //建立文件
             var ret = c.CreateNote(
                 new Note()