diff --git a/Iyzipay/IyzipayResourceV2.cs b/Iyzipay/IyzipayResourceV2.cs
index 194e35a..979211c 100644
--- a/Iyzipay/IyzipayResourceV2.cs
+++ b/Iyzipay/IyzipayResourceV2.cs
@@ -1,9 +1,10 @@
 using System;
 using System.Collections.Generic;
-using System.Net;
 using System.Linq;
 using System.Net.Http;
 using System.Net.Http.Headers;
+using Newtonsoft.Json.Serialization;
+using Newtonsoft.Json;
 
 namespace Iyzipay
 {
@@ -71,8 +72,11 @@ private static String PrepareAuthorizationStringWithRequestBody(BaseRequestV2 re
         {
             String randomKey = GenerateRandomKey();
             String uriPath = FindUriPath(url);
-
-            String payload = request != null ? uriPath + JsonBuilder.SerializeObjectToPrettyJson(request) : uriPath;
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            String payload = request != null ? uriPath + JsonConvert.SerializeObject(request, settings) : uriPath;
             String dataToEncrypt = randomKey + payload;
             String hash = HashGeneratorV2.GenerateHash(options.ApiKey, options.SecretKey, randomKey, dataToEncrypt); 
             return IYZIWS_V2_HEADER_NAME + hash;
diff --git a/Iyzipay/RestHttpClientV2.cs b/Iyzipay/RestHttpClientV2.cs
index b8c9e82..9d471fd 100644
--- a/Iyzipay/RestHttpClientV2.cs
+++ b/Iyzipay/RestHttpClientV2.cs
@@ -3,9 +3,9 @@
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Http;
-using System.Net.Http.Headers;
-using System.Linq;
 using System.Threading.Tasks;
+using Newtonsoft.Json.Serialization;
+using System.Text;
 
 namespace Iyzipay
 {
@@ -45,12 +45,18 @@ public T Get<T>(String url, Dictionary<string, string> headers) where T : Iyzipa
 
 		public T Post<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
 		{
-			HttpRequestMessage requestMessage = new HttpRequestMessage
-			{
-				Method = HttpMethod.Post,
-				RequestUri = new Uri(url),
-				Content = JsonBuilder.ToJsonString(request)
-			};
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
+
+            HttpRequestMessage requestMessage = new HttpRequestMessage
+            {
+                Method = HttpMethod.Post,
+                RequestUri = new Uri(url),
+                Content = content
+            };
 
 			foreach (var header in headers)
 			{
@@ -64,14 +70,20 @@ public T Post<T>(String url, Dictionary<string, string> headers, BaseRequestV2 r
 		}
 		public async Task<T> PostAsync<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
 		{
-			HttpRequestMessage requestMessage = new HttpRequestMessage
-			{
-				Method = HttpMethod.Post,
-				RequestUri = new Uri(url),
-				Content = JsonBuilder.ToJsonString(request)
-			};
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
 
-			foreach (var header in headers)
+            HttpRequestMessage requestMessage = new HttpRequestMessage
+            {
+                Method = HttpMethod.Post,
+                RequestUri = new Uri(url),
+                Content = content
+            };
+
+            foreach (var header in headers)
 			{
 				requestMessage.Headers.Add(header.Key, header.Value);
 			}
@@ -85,14 +97,20 @@ public async Task<T> PostAsync<T>(String url, Dictionary<string, string> headers
 
 		public T Put<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
 		{
-			HttpRequestMessage requestMessage = new HttpRequestMessage
-			{
-				Method = HttpMethod.Put,
-				RequestUri = new Uri(url),
-				Content = JsonBuilder.ToJsonString(request)
-			};
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
 
-			foreach (var header in headers)
+            HttpRequestMessage requestMessage = new HttpRequestMessage
+            {
+                Method = HttpMethod.Put,
+                RequestUri = new Uri(url),
+                Content = content
+            };
+
+            foreach (var header in headers)
 			{
 				requestMessage.Headers.Add(header.Key, header.Value);
 			}
@@ -105,14 +123,20 @@ public T Put<T>(String url, Dictionary<string, string> headers, BaseRequestV2 re
 
 		public async Task<T> PutAsync<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
 		{
-			HttpRequestMessage requestMessage = new HttpRequestMessage
-			{
-				Method = HttpMethod.Put,
-				RequestUri = new Uri(url),
-				Content = JsonBuilder.ToJsonString(request)
-			};
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
 
-			foreach (var header in headers)
+            HttpRequestMessage requestMessage = new HttpRequestMessage
+            {
+                Method = HttpMethod.Put,
+                RequestUri = new Uri(url),
+                Content = content
+            };
+
+            foreach (var header in headers)
 			{
 				requestMessage.Headers.Add(header.Key, header.Value);
 			}
@@ -127,11 +151,17 @@ public async Task<T> PutAsync<T>(String url, Dictionary<string, string> headers,
 
 		public T Patch<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
         {
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
+
             HttpRequestMessage requestMessage = new HttpRequestMessage
             {
-                Method = HttpMethod.Put,//todo: [EY] Patch olarak değiştirilmeli fakat kütüphane güncellenmesi gerekiyor.
+                Method = HttpMethod.Put,
                 RequestUri = new Uri(url),
-                Content = JsonBuilder.ToJsonString(request)
+                Content = content
             };
 
             foreach (var header in headers)
@@ -147,14 +177,20 @@ public T Patch<T>(String url, Dictionary<string, string> headers, BaseRequestV2
 
 		public T Delete<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
 		{
-			HttpRequestMessage requestMessage = new HttpRequestMessage
-			{
-				Method = HttpMethod.Delete,
-				RequestUri = new Uri(url),
-				Content = JsonBuilder.ToJsonString(request)
-			};
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
 
-			foreach (var header in headers)
+            HttpRequestMessage requestMessage = new HttpRequestMessage
+            {
+                Method = HttpMethod.Delete,
+                RequestUri = new Uri(url),
+                Content = content
+            };
+
+            foreach (var header in headers)
 			{
 				requestMessage.Headers.Add(header.Key, header.Value);
 			}
@@ -167,14 +203,20 @@ public T Delete<T>(String url, Dictionary<string, string> headers, BaseRequestV2
 
 		public async Task<T> DeleteAsync<T>(String url, Dictionary<string, string> headers, BaseRequestV2 request) where T : IyzipayResourceV2
 		{
-			HttpRequestMessage requestMessage = new HttpRequestMessage
-			{
-				Method = HttpMethod.Delete,
-				RequestUri = new Uri(url),
-				Content = JsonBuilder.ToJsonString(request)
-			};
+            var settings = new JsonSerializerSettings
+            {
+                ContractResolver = new CamelCasePropertyNamesContractResolver(),
+            };
+            var content = new StringContent(JsonConvert.SerializeObject(request, settings), Encoding.UTF8, "application/json");
 
-			foreach (var header in headers)
+            HttpRequestMessage requestMessage = new HttpRequestMessage
+            {
+                Method = HttpMethod.Delete,
+                RequestUri = new Uri(url),
+                Content = content
+            };
+
+            foreach (var header in headers)
 			{
 				requestMessage.Headers.Add(header.Key, header.Value);
 			}