diff --git a/.gitignore b/.gitignore
index 1bc915c..c1ac7dd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -154,3 +154,6 @@ $RECYCLE.BIN/
 
 # Mac desktop service store files
 .DS_Store
+
+# Visual Studio 2015 cache/options directory
+.vs/
\ No newline at end of file
diff --git a/Openpay/BankAccountService.cs b/Openpay/BankAccountService.cs
index 77acb71..6a8c4fb 100644
--- a/Openpay/BankAccountService.cs
+++ b/Openpay/BankAccountService.cs
@@ -1,13 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Openpay.Entities;
+using Openpay.Entities;
 using Openpay.Entities.Request;
+using System.Collections.Generic;
 
 namespace Openpay
 {
-    public class BankAccountService : OpenpayResourceService<BankAccount, BankAccount>
+    public class BankAccountService : OpenpayResourceService<BankAccount, BankAccount>, IBankAccountService
     {
 
         public BankAccountService(string api_key, string merchant_id, bool production = false)
@@ -32,7 +29,7 @@ public BankAccount Create(BankAccount bankAccount)
             return base.Create(null, bankAccount);
         }
 
-       
+
 
         public new void Delete(string customer_id, string bankAccount_id)
         {
diff --git a/Openpay/CardService.cs b/Openpay/CardService.cs
index 6ba9b19..e21b5e0 100644
--- a/Openpay/CardService.cs
+++ b/Openpay/CardService.cs
@@ -1,14 +1,10 @@
 using Openpay.Entities;
 using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class CardService : OpenpayResourceService<Card, Card>
+    public class CardService : OpenpayResourceService<Card, Card>, ICardService
     {
         public CardService(string api_key, string merchant_id, bool production = false)
             : base(api_key, merchant_id, production)
@@ -62,17 +58,17 @@ public List<Card> List(SearchParams filters = null)
             return base.List(null, filters);
         }
 
-		public PointsBalance Points(string card_id)
-		{
-			string ep = GetEndPoint(null, card_id) + "/points";
-			return this.httpClient.Get<PointsBalance>(ep);
-		}
+        public PointsBalance Points(string card_id)
+        {
+            string ep = GetEndPoint(null, card_id) + "/points";
+            return this.httpClient.Get<PointsBalance>(ep);
+        }
 
-		public PointsBalance Points(string customer_id, string card_id)
-		{
-			string ep = GetEndPoint(customer_id, card_id) + "/points";
-			return this.httpClient.Get<PointsBalance>(ep);
-		}
+        public PointsBalance Points(string customer_id, string card_id)
+        {
+            string ep = GetEndPoint(customer_id, card_id) + "/points";
+            return this.httpClient.Get<PointsBalance>(ep);
+        }
 
-	}
+    }
 }
diff --git a/Openpay/ChargeService.cs b/Openpay/ChargeService.cs
index 3852265..bb70a06 100644
--- a/Openpay/ChargeService.cs
+++ b/Openpay/ChargeService.cs
@@ -1,13 +1,11 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Openpay.Entities;
+using Openpay.Entities;
 using Openpay.Entities.Request;
+using System;
+using System.Collections.Generic;
 
 namespace Openpay
 {
-    public class ChargeService : OpenpayResourceService<ChargeRequest, Charge>
+    public class ChargeService : OpenpayResourceService<ChargeRequest, Charge>, IChargeService
     {
 
         public ChargeService(string api_key, string merchant_id, bool production = false)
@@ -27,36 +25,36 @@ public Charge Refund(string charge_id, string description)
             return this.Refund(null, charge_id, description);
         }
 
-		public Charge Refund(string charge_id, string description, Decimal? amount)
-		{
-			return this.Refund(null, charge_id, description, amount);
-		}
+        public Charge Refund(string charge_id, string description, Decimal? amount)
+        {
+            return this.Refund(null, charge_id, description, amount);
+        }
 
-		public Charge Refund(string customer_id, string charge_id, string description)
+        public Charge Refund(string customer_id, string charge_id, string description)
         {
             return this.Refund(customer_id, charge_id, description, null);
-		}
-
-		public Charge Refund(string customer_id, string charge_id, string description, Decimal? amount)
-		{
-			if (charge_id == null)
-				throw new ArgumentNullException("charge_id cannot be null");
-			string ep = GetEndPoint(customer_id, charge_id) + "/refund";
-			RefundRequest request = new RefundRequest();
-			request.Description = description;
-
-			if (amount != null)
-				request.Amount = amount;
-			
-			return this.httpClient.Post<Charge>(ep, request);
-		}
+        }
+
+        public Charge Refund(string customer_id, string charge_id, string description, Decimal? amount)
+        {
+            if (charge_id == null)
+                throw new ArgumentNullException("charge_id cannot be null");
+            string ep = GetEndPoint(customer_id, charge_id) + "/refund";
+            RefundRequest request = new RefundRequest();
+            request.Description = description;
+
+            if (amount != null)
+                request.Amount = amount;
+
+            return this.httpClient.Post<Charge>(ep, request);
+        }
 
         public Charge Capture(string charge_id, Decimal? amount)
         {
             return this.Capture(null, charge_id, amount);
         }
 
-        public Charge Capture(string customer_id , string charge_id, Decimal? amount)
+        public Charge Capture(string customer_id, string charge_id, Decimal? amount)
         {
             if (charge_id == null)
                 throw new ArgumentNullException("charge_id cannot be null");
@@ -72,13 +70,13 @@ public Charge Create(ChargeRequest charge_request)
         }
 
         public new Charge Create(string customer_id, ChargeRequest charge_request)
-        { 
+        {
             return base.Create(customer_id, charge_request);
         }
 
         public Charge CancelByMerchant(string merchant_id, string charge_id, ChargeRequest charge_request)
         {
-             return base.CancelByMerchant(merchant_id, charge_id,  charge_request);
+            return base.CancelByMerchant(merchant_id, charge_id, charge_request);
         }
 
         public new Charge Get(string customer_id, string charge_id)
@@ -100,6 +98,6 @@ public List<Charge> List(SearchParams filters = null)
         {
             return base.List(null, filters);
         }
-      
+
     }
 }
diff --git a/Openpay/CustomerService.cs b/Openpay/CustomerService.cs
index fc10b65..29230b6 100644
--- a/Openpay/CustomerService.cs
+++ b/Openpay/CustomerService.cs
@@ -1,14 +1,10 @@
 using Openpay.Entities;
 using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class CustomerService : OpenpayResourceService<Customer, Customer>
+    public class CustomerService : OpenpayResourceService<Customer, Customer>, ICustomerService
     {
 
         public CustomerService(string api_key, string merchant_id, bool production = false)
diff --git a/Openpay/FeeService.cs b/Openpay/FeeService.cs
index 2f58944..86eeb82 100644
--- a/Openpay/FeeService.cs
+++ b/Openpay/FeeService.cs
@@ -1,14 +1,11 @@
 using Openpay.Entities;
 using Openpay.Entities.Request;
-using Openpay.Utils;
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class FeeService : OpenpayResourceService<FeeRequest, Fee>
+    public class FeeService : OpenpayResourceService<FeeRequest, Fee>, IFeeService
     {
 
         public FeeService(string api_key, string merchant_id, bool production = false)
@@ -33,17 +30,17 @@ public List<Fee> List(SearchParams filters = null)
             return base.List(null, filters);
         }
 
-		public Fee Refund(string charge_id, string description)
-		{
-			if (charge_id == null)
-				throw new ArgumentNullException("charge_id cannot be null");
-			string ep = GetEndPoint(null, charge_id) + "/refund";
+        public Fee Refund(string charge_id, string description)
+        {
+            if (charge_id == null)
+                throw new ArgumentNullException("charge_id cannot be null");
+            string ep = GetEndPoint(null, charge_id) + "/refund";
 
-			RefundRequest request = new RefundRequest();
-			request.Description = description;
+            RefundRequest request = new RefundRequest();
+            request.Description = description;
 
-			return this.httpClient.Post<Fee>(ep, request);
-		}
+            return this.httpClient.Post<Fee>(ep, request);
+        }
 
-	}
+    }
 }
diff --git a/Openpay/IBankAccountService.cs b/Openpay/IBankAccountService.cs
new file mode 100644
index 0000000..4ab3d58
--- /dev/null
+++ b/Openpay/IBankAccountService.cs
@@ -0,0 +1,18 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IBankAccountService
+    {
+        BankAccount Create(BankAccount bankAccount);
+        BankAccount Create(string customer_id, BankAccount bankAccount);
+        void Delete(string bankAccount_id);
+        void Delete(string customer_id, string bankAccount_id);
+        BankAccount Get(string bankAccount_id);
+        BankAccount Get(string customer_id, string bankAccount_id);
+        List<BankAccount> List(SearchParams filters = null);
+        List<BankAccount> List(string customer_id, SearchParams filters = null);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/ICardService.cs b/Openpay/ICardService.cs
new file mode 100644
index 0000000..b4a5b21
--- /dev/null
+++ b/Openpay/ICardService.cs
@@ -0,0 +1,20 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface ICardService
+    {
+        Card Create(Card card);
+        Card Create(string customer_id, Card card);
+        void Delete(string card_id);
+        void Delete(string customer_id, string card_id);
+        Card Get(string card_id);
+        Card Get(string customer_id, string card_id);
+        List<Card> List(SearchParams filters = null);
+        List<Card> List(string customer_id, SearchParams filters = null);
+        PointsBalance Points(string card_id);
+        PointsBalance Points(string customer_id, string card_id);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IChargeService.cs b/Openpay/IChargeService.cs
new file mode 100644
index 0000000..ff9d9d3
--- /dev/null
+++ b/Openpay/IChargeService.cs
@@ -0,0 +1,23 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IChargeService
+    {
+        Charge CancelByMerchant(string merchant_id, string charge_id, ChargeRequest charge_request);
+        Charge Capture(string charge_id, decimal? amount);
+        Charge Capture(string customer_id, string charge_id, decimal? amount);
+        Charge Create(ChargeRequest charge_request);
+        Charge Create(string customer_id, ChargeRequest charge_request);
+        Charge Get(string charge_id);
+        Charge Get(string customer_id, string charge_id);
+        List<Charge> List(SearchParams filters = null);
+        List<Charge> List(string customer_id, SearchParams filters = null);
+        Charge Refund(string charge_id, string description);
+        Charge Refund(string charge_id, string description, decimal? amount);
+        Charge Refund(string customer_id, string charge_id, string description);
+        Charge Refund(string customer_id, string charge_id, string description, decimal? amount);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/ICustomerService.cs b/Openpay/ICustomerService.cs
new file mode 100644
index 0000000..56be1ce
--- /dev/null
+++ b/Openpay/ICustomerService.cs
@@ -0,0 +1,15 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface ICustomerService
+    {
+        Customer Create(Customer customer);
+        void Delete(string customer_id);
+        Customer Get(string customer_id);
+        List<Customer> List(SearchParams filters = null);
+        Customer Update(Customer customer);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IFeeService.cs b/Openpay/IFeeService.cs
new file mode 100644
index 0000000..541fc70
--- /dev/null
+++ b/Openpay/IFeeService.cs
@@ -0,0 +1,13 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IFeeService
+    {
+        Fee Create(FeeRequest request);
+        List<Fee> List(SearchParams filters = null);
+        Fee Refund(string charge_id, string description);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IMerchantService.cs b/Openpay/IMerchantService.cs
new file mode 100644
index 0000000..fae118e
--- /dev/null
+++ b/Openpay/IMerchantService.cs
@@ -0,0 +1,9 @@
+using Openpay.Entities;
+
+namespace Openpay
+{
+    public interface IMerchantService
+    {
+        Merchant Get();
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IOpenpayAPI.cs b/Openpay/IOpenpayAPI.cs
new file mode 100644
index 0000000..0ed4a35
--- /dev/null
+++ b/Openpay/IOpenpayAPI.cs
@@ -0,0 +1,20 @@
+namespace Openpay
+{
+    public interface IOpenpayAPI
+    {
+        IBankAccountService BankAccountService { get; }
+        ICardService CardService { get; }
+        IChargeService ChargeService { get; }
+        ICustomerService CustomerService { get; }
+        IFeeService FeeService { get; }
+        IMerchantService MerchantService { get; set; }
+        IOpenpayFeesService OpenpayFeesService { get; }
+        IPayoutReportService PayoutReportService { get; }
+        IPayoutService PayoutService { get; }
+        IPlanService PlanService { get; }
+        bool Production { get; set; }
+        ISubscriptionService SubscriptionService { get; }
+        ITransferService TransferService { get; }
+        IWebhookService WebhooksService { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IOpenpayFeesService.cs b/Openpay/IOpenpayFeesService.cs
new file mode 100644
index 0000000..f473cc3
--- /dev/null
+++ b/Openpay/IOpenpayFeesService.cs
@@ -0,0 +1,12 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IOpenpayFeesService
+    {
+        List<Transaction> Details(int year, int month, string fee_type, PaginationParams paginationParams);
+        OpenpayFeesSummary Summary(int year, int month);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IPayoutReportService.cs b/Openpay/IPayoutReportService.cs
new file mode 100644
index 0000000..ea8b2f0
--- /dev/null
+++ b/Openpay/IPayoutReportService.cs
@@ -0,0 +1,12 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IPayoutReportService
+    {
+        List<Transaction> Detail(string payout_id, PayoutReportDetailSearchParams searchParams);
+        PayoutSummary Get(string payout_id);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IPayoutService.cs b/Openpay/IPayoutService.cs
new file mode 100644
index 0000000..d5bac40
--- /dev/null
+++ b/Openpay/IPayoutService.cs
@@ -0,0 +1,18 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IPayoutService
+    {
+        void Cancel(string payout_id);
+        void Cancel(string customer_id, string payout_id);
+        Payout Create(PayoutRequest payout_request);
+        Payout Create(string customer_id, PayoutRequest payout_request);
+        Payout Get(string payout_id);
+        Payout Get(string customer_id, string payout_id);
+        List<Payout> List(SearchParams filters = null);
+        List<Payout> List(string customer_id, SearchParams filters = null);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IPlanService.cs b/Openpay/IPlanService.cs
new file mode 100644
index 0000000..8302013
--- /dev/null
+++ b/Openpay/IPlanService.cs
@@ -0,0 +1,16 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IPlanService
+    {
+        Plan Create(Plan plan);
+        void Delete(string plan_id);
+        Plan Get(string plan_id);
+        List<Plan> List(SearchParams filters = null);
+        List<Subscription> Subscriptions(string plan_id, SearchParams filters = null);
+        Plan Update(Plan plan);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/ISubscriptionService.cs b/Openpay/ISubscriptionService.cs
new file mode 100644
index 0000000..b6c477d
--- /dev/null
+++ b/Openpay/ISubscriptionService.cs
@@ -0,0 +1,15 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface ISubscriptionService
+    {
+        Subscription Create(string customer_id, Subscription subscription);
+        void Delete(string customer_id, string subscription_id);
+        Subscription Get(string customer_id, string subscription_id);
+        List<Subscription> List(string customer_id, SearchParams filters = null);
+        Subscription Update(string customer_id, Subscription subscription);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/ITransferService.cs b/Openpay/ITransferService.cs
new file mode 100644
index 0000000..28c9f9e
--- /dev/null
+++ b/Openpay/ITransferService.cs
@@ -0,0 +1,13 @@
+using Openpay.Entities;
+using Openpay.Entities.Request;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface ITransferService
+    {
+        Transfer Create(string customer_id, TransferRequest request);
+        Transfer Get(string customer_id, string transfer_id);
+        List<Transfer> List(string customer_id, SearchParams filters = null);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/IWebhookService.cs b/Openpay/IWebhookService.cs
new file mode 100644
index 0000000..68a5241
--- /dev/null
+++ b/Openpay/IWebhookService.cs
@@ -0,0 +1,38 @@
+/*
+ * COPYRIGHT © 2014. OPENPAY.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Class: WebhookService.cs
+ * 
+ * Change control:
+ * ---------------------------------------------------------------------------------------
+ * Version | Date       | Name                                      | Description
+ * ---------------------------------------------------------------------------------------
+ *   1.0	2014-12-01	Marcos Coronado marcos.coronado@openpay.mx	 Creating Class.
+ *
+ */
+using Openpay.Entities;
+using System.Collections.Generic;
+
+namespace Openpay
+{
+    public interface IWebhookService
+    {
+        Webhook Create(Webhook webhook);
+        void Delete(string webhook_id);
+        Webhook Get(string webhook_id);
+        List<Webhook> List();
+        void Verify(string webhook_id, string verification_code);
+    }
+}
\ No newline at end of file
diff --git a/Openpay/MerchantService.cs b/Openpay/MerchantService.cs
index dd2c3b4..7a4864d 100644
--- a/Openpay/MerchantService.cs
+++ b/Openpay/MerchantService.cs
@@ -1,14 +1,8 @@
 using Openpay.Entities;
-using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class MerchantService : OpenpayResourceService<Merchant, Merchant>
+    public class MerchantService : OpenpayResourceService<Merchant, Merchant>, IMerchantService
     {
 
         public MerchantService(string api_key, string merchant_id, bool production = false)
@@ -27,6 +21,6 @@ public Merchant Get()
         {
             return base.Get(null, null);
         }
-       
+
     }
 }
diff --git a/Openpay/Openpay.csproj b/Openpay/Openpay.csproj
index 8fb7891..554cdf2 100644
--- a/Openpay/Openpay.csproj
+++ b/Openpay/Openpay.csproj
@@ -50,6 +50,20 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Entities\Merchant.cs" />
+    <Compile Include="IBankAccountService.cs" />
+    <Compile Include="ICardService.cs" />
+    <Compile Include="IChargeService.cs" />
+    <Compile Include="ICustomerService.cs" />
+    <Compile Include="IFeeService.cs" />
+    <Compile Include="IMerchantService.cs" />
+    <Compile Include="IOpenpayAPI.cs" />
+    <Compile Include="IOpenpayFeesService.cs" />
+    <Compile Include="IPayoutReportService.cs" />
+    <Compile Include="IPayoutService.cs" />
+    <Compile Include="IPlanService.cs" />
+    <Compile Include="ISubscriptionService.cs" />
+    <Compile Include="ITransferService.cs" />
+    <Compile Include="IWebhookService.cs" />
     <Compile Include="MerchantService.cs" />
     <Compile Include="Entities\CardPoints.cs" />
     <Compile Include="Entities\Store.cs" />
@@ -107,6 +121,9 @@
       <SubType>Designer</SubType>
     </None>
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="Interfaces\" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
diff --git a/Openpay/OpenpayAPI.cs b/Openpay/OpenpayAPI.cs
index 2bdc4be..e8b0474 100644
--- a/Openpay/OpenpayAPI.cs
+++ b/Openpay/OpenpayAPI.cs
@@ -1,41 +1,36 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-namespace Openpay
+namespace Openpay
 {
-    public class OpenpayAPI
+    public class OpenpayAPI : IOpenpayAPI
     {
-        public CustomerService CustomerService { get; internal set; }
+        public ICustomerService CustomerService { get; internal set; }
 
-        public CardService CardService { get; internal set; }
+        public ICardService CardService { get; internal set; }
 
-        public BankAccountService BankAccountService { get; internal set; }
+        public IBankAccountService BankAccountService { get; internal set; }
 
-        public ChargeService ChargeService { get; internal set; }
+        public IChargeService ChargeService { get; internal set; }
 
-		public PayoutReportService PayoutReportService { get; internal set; }
+        public IPayoutReportService PayoutReportService { get; internal set; }
 
-        public TransferService TransferService { get; internal set; }
+        public ITransferService TransferService { get; internal set; }
 
-        public PayoutService PayoutService { get; internal set; }
+        public IPayoutService PayoutService { get; internal set; }
 
-        public FeeService FeeService { get; internal set; }
+        public IFeeService FeeService { get; internal set; }
 
-        public PlanService PlanService { get; internal set; }
+        public IPlanService PlanService { get; internal set; }
 
-        public SubscriptionService SubscriptionService { get; internal set; }
+        public ISubscriptionService SubscriptionService { get; internal set; }
 
-		public OpenpayFeesService OpenpayFeesService { get; internal set; }
+        public IOpenpayFeesService OpenpayFeesService { get; internal set; }
 
-		public WebhookService WebhooksService { get; set; }
+        public IWebhookService WebhooksService { get; set; }
 
-        public MerchantService MerchantService { get; set; }
+        public IMerchantService MerchantService { get; set; }
 
-        private OpenpayHttpClient httpClient;
+        private readonly OpenpayHttpClient httpClient;
 
-        public OpenpayAPI( string api_key, string merchant_id,bool production = false)
+        public OpenpayAPI(string api_key, string merchant_id, bool production = false)
         {
             this.httpClient = new OpenpayHttpClient(api_key, merchant_id, production);
             CustomerService = new CustomerService(this.httpClient);
@@ -47,13 +42,14 @@ public OpenpayAPI( string api_key, string merchant_id,bool production = false)
             FeeService = new FeeService(this.httpClient);
             PlanService = new PlanService(this.httpClient);
             SubscriptionService = new SubscriptionService(this.httpClient);
-			OpenpayFeesService = new OpenpayFeesService(this.httpClient);
-			WebhooksService = new WebhookService (this.httpClient);
-			PayoutReportService = new PayoutReportService (this.httpClient);
-            MerchantService = new MerchantService (this.httpClient);
+            OpenpayFeesService = new OpenpayFeesService(this.httpClient);
+            WebhooksService = new WebhookService(this.httpClient);
+            PayoutReportService = new PayoutReportService(this.httpClient);
+            MerchantService = new MerchantService(this.httpClient);
         }
 
-        public bool Production {
+        public bool Production
+        {
             get
             {
                 return this.httpClient.Production;
diff --git a/Openpay/OpenpayFeesService.cs b/Openpay/OpenpayFeesService.cs
index 2fbb3e1..9b0a34e 100644
--- a/Openpay/OpenpayFeesService.cs
+++ b/Openpay/OpenpayFeesService.cs
@@ -3,64 +3,63 @@
 using Openpay.Utils;
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-	public class OpenpayFeesService
-	{
-		internal OpenpayHttpClient httpClient;
+    public class OpenpayFeesService : IOpenpayFeesService
+    {
+        internal OpenpayHttpClient httpClient;
 
-		public OpenpayFeesService(string api_key, string merchant_id, bool production = false)
-		{
-			this.httpClient = new OpenpayHttpClient(api_key, merchant_id, production);
-		}
+        public OpenpayFeesService(string api_key, string merchant_id, bool production = false)
+        {
+            this.httpClient = new OpenpayHttpClient(api_key, merchant_id, production);
+        }
 
-		internal OpenpayFeesService(OpenpayHttpClient opHttpClient)
-		{
-			this.httpClient = opHttpClient;
-		}
+        internal OpenpayFeesService(OpenpayHttpClient opHttpClient)
+        {
+            this.httpClient = opHttpClient;
+        }
 
-		internal String GetEndPoint()
-		{
-			return "/reports/fees";
-		}
+        internal String GetEndPoint()
+        {
+            return "/reports/fees";
+        }
 
-		public OpenpayFeesSummary Summary(int year, int month)
-		{
-			string url = GetEndPoint();
-			url = url + BuildParams(year, month, null, null);
-			return this.httpClient.Get<OpenpayFeesSummary>(url);
-		}
+        public OpenpayFeesSummary Summary(int year, int month)
+        {
+            string url = GetEndPoint();
+            url = url + BuildParams(year, month, null, null);
+            return this.httpClient.Get<OpenpayFeesSummary>(url);
+        }
 
-		public List<Transaction> Details(int year, int month, string fee_type, PaginationParams paginationParams)
-		{
-			string url = GetEndPoint() + "/detail";
-			url = url + BuildParams(year, month, fee_type, paginationParams);
-			return this.httpClient.Get<List<Transaction>>(url);
-		}
+        public List<Transaction> Details(int year, int month, string fee_type, PaginationParams paginationParams)
+        {
+            string url = GetEndPoint() + "/detail";
+            url = url + BuildParams(year, month, fee_type, paginationParams);
+            return this.httpClient.Get<List<Transaction>>(url);
+        }
 
-		internal string BuildParams(int year, int month, string fee_type, PaginationParams paginationParams)
-		{
-			string url_params = string.Empty;
-			url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "year", year.ToString());
-			url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "month", month.ToString());
-			if (fee_type != null) {
-				url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "fee_type", fee_type);
-			}
-			if (paginationParams != null)
-			{
-				if (paginationParams.Offset < 0)
-					throw new ArgumentOutOfRangeException("offset");
-				if (paginationParams.Limit < 1 || paginationParams.Limit > 100)
-					throw new ArgumentOutOfRangeException("limit");
+        internal string BuildParams(int year, int month, string fee_type, PaginationParams paginationParams)
+        {
+            string url_params = string.Empty;
+            url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "year", year.ToString());
+            url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "month", month.ToString());
+            if (fee_type != null)
+            {
+                url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "fee_type", fee_type);
+            }
+            if (paginationParams != null)
+            {
+                if (paginationParams.Offset < 0)
+                    throw new ArgumentOutOfRangeException("offset");
+                if (paginationParams.Limit < 1 || paginationParams.Limit > 100)
+                    throw new ArgumentOutOfRangeException("limit");
 
-				url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "limit", paginationParams.Limit.ToString());
-				url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "offset", paginationParams.Offset.ToString());
-			}
-			return url_params;
-		}
-	}
+                url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "limit", paginationParams.Limit.ToString());
+                url_params = ParameterBuilder.ApplyParameterToUrl(url_params, "offset", paginationParams.Offset.ToString());
+            }
+            return url_params;
+        }
+    }
 }
 
diff --git a/Openpay/OpenpayHttpClient.cs b/Openpay/OpenpayHttpClient.cs
index 64ec652..464fc1e 100644
--- a/Openpay/OpenpayHttpClient.cs
+++ b/Openpay/OpenpayHttpClient.cs
@@ -1,15 +1,13 @@
 using Newtonsoft.Json;
 using Openpay.Entities;
 using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Net;
 using System.Text;
 
 namespace Openpay
 {
-    public class OpenpayHttpClient
+    public class OpenpayHttpClient 
     {
         private static readonly string api_endpoint = "https://api.openpay.mx/v1/";
         private static readonly string api_endpoint_sandbox = "https://sandbox-api.openpay.mx/v1/";
@@ -37,14 +35,17 @@ public OpenpayHttpClient(string api_key, string merchant_id, bool production = f
             Production = production;
         }
 
-        public bool Production { 
-            get { 
-                return _isProduction; 
-            } 
-            set { 
+        public bool Production
+        {
+            get
+            {
+                return _isProduction;
+            }
+            set
+            {
                 APIEndpoint = value ? api_endpoint : api_endpoint_sandbox;
                 _isProduction = value;
-            } 
+            }
         }
 
         protected virtual WebRequest SetupRequest(string method, string url)
@@ -80,10 +81,10 @@ public T Post<T>(string endpoint, JsonObject obj)
             return JsonConvert.DeserializeObject<T>(json);
         }
 
-		public void Post<T>(string endpoint)
-		{
-			DoRequest(endpoint, HttpMethod.POST, null);
-		}
+        public void Post<T>(string endpoint)
+        {
+            DoRequest(endpoint, HttpMethod.POST, null);
+        }
 
         public T Get<T>(string endpoint)
         {
diff --git a/Openpay/PayoutReportService.cs b/Openpay/PayoutReportService.cs
index d97f6c4..82a6da1 100644
--- a/Openpay/PayoutReportService.cs
+++ b/Openpay/PayoutReportService.cs
@@ -1,42 +1,41 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Openpay.Entities;
+using Openpay.Entities;
 using Openpay.Entities.Request;
 using Openpay.Utils;
+using System;
+using System.Collections.Generic;
 
 namespace Openpay
 {
-	public class PayoutReportService : OpenpayGenericService
+    public class PayoutReportService : OpenpayGenericService, IPayoutReportService
     {
 
-		public PayoutReportService(string api_key, string merchant_id, bool production = false)
+        public PayoutReportService(string api_key, string merchant_id, bool production = false)
             : base(api_key, merchant_id, production) { }
 
-		internal PayoutReportService(OpenpayHttpClient opHttpClient)
+        internal PayoutReportService(OpenpayHttpClient opHttpClient)
             : base(opHttpClient) { }
 
-		public PayoutSummary Get(string payout_id)
+        public PayoutSummary Get(string payout_id)
         {
-			return base.Get<PayoutSummary>("/reports/payout/" + payout_id);
+            return base.Get<PayoutSummary>("/reports/payout/" + payout_id);
         }
 
-		public List<Transaction> Detail(string payout_id, PayoutReportDetailSearchParams searchParams)
-		{
-			string url = "/reports/payout/" + payout_id + "/detail";
-			if (searchParams != null) {
-				if (searchParams.Offset < 0)
-					throw new ArgumentOutOfRangeException ("offset");
-				if (searchParams.Limit < 1 || searchParams.Limit > 100)
-					throw new ArgumentOutOfRangeException ("limit");
-				url = ParameterBuilder.ApplyParameterToUrl(url, "limit", searchParams.Limit.ToString());
-				url = ParameterBuilder.ApplyParameterToUrl(url, "offset", searchParams.Offset.ToString());
-				if (searchParams.DetailType != null)
-					url = ParameterBuilder.ApplyParameterToUrl(url, "detail_type", searchParams.DetailType);
-			}
-			return base.List<Transaction>(url);
-		}
+        public List<Transaction> Detail(string payout_id, PayoutReportDetailSearchParams searchParams)
+        {
+            string url = "/reports/payout/" + payout_id + "/detail";
+            if (searchParams != null)
+            {
+                if (searchParams.Offset < 0)
+                    throw new ArgumentOutOfRangeException("offset");
+                if (searchParams.Limit < 1 || searchParams.Limit > 100)
+                    throw new ArgumentOutOfRangeException("limit");
+                url = ParameterBuilder.ApplyParameterToUrl(url, "limit", searchParams.Limit.ToString());
+                url = ParameterBuilder.ApplyParameterToUrl(url, "offset", searchParams.Offset.ToString());
+                if (searchParams.DetailType != null)
+                    url = ParameterBuilder.ApplyParameterToUrl(url, "detail_type", searchParams.DetailType);
+            }
+            return base.List<Transaction>(url);
+        }
 
     }
 }
diff --git a/Openpay/PayoutService.cs b/Openpay/PayoutService.cs
index 75d0c50..0935ef2 100644
--- a/Openpay/PayoutService.cs
+++ b/Openpay/PayoutService.cs
@@ -1,13 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Openpay.Entities;
+using Openpay.Entities;
 using Openpay.Entities.Request;
+using System.Collections.Generic;
 
 namespace Openpay
 {
-    public class PayoutService : OpenpayResourceService<PayoutRequest, Payout>
+    public class PayoutService : OpenpayResourceService<PayoutRequest, Payout>, IPayoutService
     {
 
         public PayoutService(string api_key, string merchant_id, bool production = false)
@@ -42,15 +39,15 @@ public Payout Get(string payout_id)
             return base.Get(null, payout_id);
         }
 
-		public void Cancel(string customer_id, string payout_id)
-		{
-			base.Delete(customer_id, payout_id);
-		}
+        public void Cancel(string customer_id, string payout_id)
+        {
+            base.Delete(customer_id, payout_id);
+        }
 
-		public void Cancel(string payout_id)
-		{
-			base.Delete(null, payout_id);
-		}
+        public void Cancel(string payout_id)
+        {
+            base.Delete(null, payout_id);
+        }
 
         public new List<Payout> List(string customer_id, SearchParams filters = null)
         {
@@ -61,6 +58,6 @@ public List<Payout> List(SearchParams filters = null)
         {
             return base.List(null, filters);
         }
-      
+
     }
 }
diff --git a/Openpay/PlanService.cs b/Openpay/PlanService.cs
index 90ac2fe..3462430 100644
--- a/Openpay/PlanService.cs
+++ b/Openpay/PlanService.cs
@@ -1,14 +1,10 @@
 using Openpay.Entities;
 using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class PlanService : OpenpayResourceService<Plan, Plan>
+    public class PlanService : OpenpayResourceService<Plan, Plan>, IPlanService
     {
 
         public PlanService(string api_key, string merchant_id, bool production = false)
diff --git a/Openpay/SubscriptionService.cs b/Openpay/SubscriptionService.cs
index ec52897..b1b9bfe 100644
--- a/Openpay/SubscriptionService.cs
+++ b/Openpay/SubscriptionService.cs
@@ -1,14 +1,10 @@
 using Openpay.Entities;
 using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class SubscriptionService : OpenpayResourceService<Subscription, Subscription>
+    public class SubscriptionService : OpenpayResourceService<Subscription, Subscription>, ISubscriptionService
     {
 
         public SubscriptionService(string api_key, string merchant_id, bool production = false)
diff --git a/Openpay/TransferService.cs b/Openpay/TransferService.cs
index 6a74f15..033f161 100644
--- a/Openpay/TransferService.cs
+++ b/Openpay/TransferService.cs
@@ -1,14 +1,10 @@
 using Openpay.Entities;
 using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-    public class TransferService : OpenpayResourceService<TransferRequest, Transfer>
+    public class TransferService : OpenpayResourceService<TransferRequest, Transfer>, ITransferService
     {
 
         public TransferService(string api_key, string merchant_id, bool production = false)
diff --git a/Openpay/WebhookService.cs b/Openpay/WebhookService.cs
index d8c9064..3f96516 100644
--- a/Openpay/WebhookService.cs
+++ b/Openpay/WebhookService.cs
@@ -23,62 +23,56 @@
  *
  */
 using Openpay.Entities;
-using Openpay.Entities.Request;
-using Openpay.Utils;
-using System;
-using System.Collections;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Openpay
 {
-	/**
+    /**
 	 * <summary>
 	 * Clase base que contiene las operaciones disponibles para la administracion de los webhooks
 	 * </summary>
 	 */
-	public class WebhookService : OpenpayResourceService<Webhook, Webhook>
-	{
+    public class WebhookService : OpenpayResourceService<Webhook, Webhook>, IWebhookService
+    {
 
-		public WebhookService(string api_key, string merchant_id, bool production = false)
-			: base(api_key, merchant_id, production)
-		{
-			ResourceName = "webhooks";
-		}
+        public WebhookService(string api_key, string merchant_id, bool production = false)
+            : base(api_key, merchant_id, production)
+        {
+            ResourceName = "webhooks";
+        }
 
-		internal WebhookService(OpenpayHttpClient opHttpClient)
-			: base(opHttpClient)
-		{
-			ResourceName = "webhooks";
-		}
+        internal WebhookService(OpenpayHttpClient opHttpClient)
+            : base(opHttpClient)
+        {
+            ResourceName = "webhooks";
+        }
 
-		public Webhook Create(Webhook webhook)
-		{
-			return base.Create(null, webhook);
-		}
+        public Webhook Create(Webhook webhook)
+        {
+            return base.Create(null, webhook);
+        }
 
-		public void Verify(string webhook_id, string verification_code)
-		{
-			string url = GetEndPoint(null, webhook_id) + "/verify" + "/" + verification_code;
-			this.httpClient.Post<Webhook>(url);
-		}
-		
-		public Webhook Get(string webhook_id)
-		{
-			return base.Get(null, webhook_id);
-		}
+        public void Verify(string webhook_id, string verification_code)
+        {
+            string url = GetEndPoint(null, webhook_id) + "/verify" + "/" + verification_code;
+            this.httpClient.Post<Webhook>(url);
+        }
 
-		public void Delete(string webhook_id)
-		{
-			base.Delete(null, webhook_id);
-		}
+        public Webhook Get(string webhook_id)
+        {
+            return base.Get(null, webhook_id);
+        }
 
-		public List<Webhook> List()
-		{
-			return base.List(null, null);
-		}
+        public void Delete(string webhook_id)
+        {
+            base.Delete(null, webhook_id);
+        }
 
-	}
+        public List<Webhook> List()
+        {
+            return base.List(null, null);
+        }
+
+    }
 }