diff --git a/Back/skydiveLogs-api.Business/Interface/IAircraftService.cs b/Back/skydiveLogs-api.Business/Interface/IAircraftService.cs
new file mode 100644
index 0000000..e039cae
--- /dev/null
+++ b/Back/skydiveLogs-api.Business/Interface/IAircraftService.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Business.Interface
+{
+    public interface IAircraftService
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Business/Interface/IDropZoneService.cs b/Back/skydiveLogs-api.Business/Interface/IDropZoneService.cs
new file mode 100644
index 0000000..25323bc
--- /dev/null
+++ b/Back/skydiveLogs-api.Business/Interface/IDropZoneService.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Business.Interface
+{
+    public interface IDropZoneService
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Business/Interface/IJumpService.cs b/Back/skydiveLogs-api.Business/Interface/IJumpService.cs
new file mode 100644
index 0000000..9e30fe3
--- /dev/null
+++ b/Back/skydiveLogs-api.Business/Interface/IJumpService.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Business.Interface
+{
+    public interface IJumpService
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Business/Interface/IJumpTypeService.cs b/Back/skydiveLogs-api.Business/Interface/IJumpTypeService.cs
new file mode 100644
index 0000000..8b2326c
--- /dev/null
+++ b/Back/skydiveLogs-api.Business/Interface/IJumpTypeService.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Business.Interface
+{
+    public interface IJumpTypeService
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Business/skydiveLogs-api.Business.csproj b/Back/skydiveLogs-api.Business/skydiveLogs-api.Business.csproj
index 8479c11..4e1543c 100644
--- a/Back/skydiveLogs-api.Business/skydiveLogs-api.Business.csproj
+++ b/Back/skydiveLogs-api.Business/skydiveLogs-api.Business.csproj
@@ -5,10 +5,6 @@
     <RootNamespace>skydiveLogs_api.Business</RootNamespace>
   </PropertyGroup>
 
-  <ItemGroup>
-    <Folder Include="Interface\" />
-  </ItemGroup>
-
   <ItemGroup>
     <ProjectReference Include="..\skydiveLogs-api.Data\skydiveLogs-api.Data.csproj" />
     <ProjectReference Include="..\skydiveLogs-api.Model\skydiveLogs-api.Model.csproj" />
diff --git a/Back/skydiveLogs-api.Data/DropZoneRepository.cs b/Back/skydiveLogs-api.Data/DropZoneRepository.cs
index ba98754..da01a9a 100644
--- a/Back/skydiveLogs-api.Data/DropZoneRepository.cs
+++ b/Back/skydiveLogs-api.Data/DropZoneRepository.cs
@@ -1,10 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using skydiveLogs_api.Data.Interface;
 
 namespace skydiveLogs_api.Data
 {
-    class DropZoneRepository
+    public class DropZoneRepository : IDropZoneRepository
     {
     }
 }
diff --git a/Back/skydiveLogs-api.Data/GearRepository.cs b/Back/skydiveLogs-api.Data/GearRepository.cs
index 3bccd4f..280ac3e 100644
--- a/Back/skydiveLogs-api.Data/GearRepository.cs
+++ b/Back/skydiveLogs-api.Data/GearRepository.cs
@@ -1,10 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using skydiveLogs_api.Data.Interface;
 
 namespace skydiveLogs_api.Data
 {
-    class GearRepository
+    public class GearRepository : IGearRepository
     {
     }
 }
diff --git a/Back/skydiveLogs-api.Data/Interface/IDropZoneRepository.cs b/Back/skydiveLogs-api.Data/Interface/IDropZoneRepository.cs
new file mode 100644
index 0000000..f1dee6c
--- /dev/null
+++ b/Back/skydiveLogs-api.Data/Interface/IDropZoneRepository.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Data.Interface
+{
+    public interface IDropZoneRepository
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Data/Interface/IGearRepository.cs b/Back/skydiveLogs-api.Data/Interface/IGearRepository.cs
new file mode 100644
index 0000000..9821582
--- /dev/null
+++ b/Back/skydiveLogs-api.Data/Interface/IGearRepository.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Data.Interface
+{
+    public interface IGearRepository
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Data/Interface/IJumpRepository.cs b/Back/skydiveLogs-api.Data/Interface/IJumpRepository.cs
new file mode 100644
index 0000000..c47d120
--- /dev/null
+++ b/Back/skydiveLogs-api.Data/Interface/IJumpRepository.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Data.Interface
+{
+    public interface IJumpRepository
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Data/Interface/IJumpTypeRepository.cs b/Back/skydiveLogs-api.Data/Interface/IJumpTypeRepository.cs
new file mode 100644
index 0000000..22ee076
--- /dev/null
+++ b/Back/skydiveLogs-api.Data/Interface/IJumpTypeRepository.cs
@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace skydiveLogs_api.Data.Interface
+{
+    public interface IJumpTypeRepository
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api.Data/JumpRepository.cs b/Back/skydiveLogs-api.Data/JumpRepository.cs
index 45b2d69..1d4d740 100644
--- a/Back/skydiveLogs-api.Data/JumpRepository.cs
+++ b/Back/skydiveLogs-api.Data/JumpRepository.cs
@@ -1,10 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using skydiveLogs_api.Data.Interface;
 
 namespace skydiveLogs_api.Data
 {
-    class JumpRepository
+    public class JumpRepository : IJumpRepository
     {
     }
 }
diff --git a/Back/skydiveLogs-api.Data/JumpTypeRepository.cs b/Back/skydiveLogs-api.Data/JumpTypeRepository.cs
index e20ec05..3c2c2fb 100644
--- a/Back/skydiveLogs-api.Data/JumpTypeRepository.cs
+++ b/Back/skydiveLogs-api.Data/JumpTypeRepository.cs
@@ -1,10 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using skydiveLogs_api.Data.Interface;
 
 namespace skydiveLogs_api.Data
 {
-    class JumpTypeRepository
+    public class JumpTypeRepository : IJumpTypeRepository
     {
     }
 }
diff --git a/Back/skydiveLogs-api/Controllers/AircraftController.cs b/Back/skydiveLogs-api/Controllers/AircraftController.cs
index 65bc5ca..86cdf0a 100644
--- a/Back/skydiveLogs-api/Controllers/AircraftController.cs
+++ b/Back/skydiveLogs-api/Controllers/AircraftController.cs
@@ -4,6 +4,8 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
+using skydiveLogs_api.Business.Interface;
+using skydiveLogs_api.DataContract;
 
 namespace skydiveLogs_api.Controllers
 {
@@ -11,6 +13,11 @@ namespace skydiveLogs_api.Controllers
     [ApiController]
     public class AircraftController : ControllerBase
     {
+        public AircraftController(IAircraftService aircraftService)
+        {
+            _aircraftService = aircraftService;
+        }
+
         // GET: api/Aircraft
         [HttpGet]
         public IEnumerable<AircraftResp> Get()
@@ -42,5 +49,7 @@ namespace skydiveLogs_api.Controllers
         public void Delete(int id)
         {
         }
+
+        private readonly IAircraftService _aircraftService;
     }
 }
diff --git a/Back/skydiveLogs-api/Controllers/DropZoneController.cs b/Back/skydiveLogs-api/Controllers/DropZoneController.cs
index 67f4460..055432c 100644
--- a/Back/skydiveLogs-api/Controllers/DropZoneController.cs
+++ b/Back/skydiveLogs-api/Controllers/DropZoneController.cs
@@ -4,6 +4,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
+using skydiveLogs_api.Business.Interface;
 using skydiveLogs_api.DataContract;
 
 namespace skydiveLogs_api.Controllers
@@ -12,6 +13,11 @@ namespace skydiveLogs_api.Controllers
     [ApiController]
     public class DropZoneController : ControllerBase
     {
+        public DropZoneController(IDropZoneService dropZoneService)
+        {
+            _dropZoneService = dropZoneService;
+        }
+
         // GET: api/DropZone
         [HttpGet]
         public IEnumerable<DropZoneResp> Get()
@@ -43,5 +49,7 @@ namespace skydiveLogs_api.Controllers
         public void Delete(int id)
         {
         }
+
+        private readonly IDropZoneService _dropZoneService;
     }
 }
diff --git a/Back/skydiveLogs-api/Controllers/JumpController.cs b/Back/skydiveLogs-api/Controllers/JumpController.cs
index f2847ab..4f0686b 100644
--- a/Back/skydiveLogs-api/Controllers/JumpController.cs
+++ b/Back/skydiveLogs-api/Controllers/JumpController.cs
@@ -4,6 +4,8 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
+using skydiveLogs_api.Business.Interface;
+using skydiveLogs_api.DataContract;
 
 namespace skydiveLogs_api.Controllers
 {
@@ -11,6 +13,11 @@ namespace skydiveLogs_api.Controllers
     [ApiController]
     public class JumpController : ControllerBase
     {
+        public JumpController(IJumpService jumpService)
+        {
+            _jumpService = jumpService;
+        }
+
         // GET: api/Jump
         [HttpGet]
         public IEnumerable<JumpResp> Get()
@@ -42,5 +49,7 @@ namespace skydiveLogs_api.Controllers
         public void Delete(int id)
         {
         }
+
+        private readonly IJumpService _jumpService;
     }
 }
diff --git a/Back/skydiveLogs-api/Controllers/JumpTypeController.cs b/Back/skydiveLogs-api/Controllers/JumpTypeController.cs
index 0fcca70..e0bb826 100644
--- a/Back/skydiveLogs-api/Controllers/JumpTypeController.cs
+++ b/Back/skydiveLogs-api/Controllers/JumpTypeController.cs
@@ -4,6 +4,8 @@ using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
+using skydiveLogs_api.Business.Interface;
+using skydiveLogs_api.DataContract;
 
 namespace skydiveLogs_api.Controllers
 {
@@ -11,6 +13,11 @@ namespace skydiveLogs_api.Controllers
     [ApiController]
     public class JumpTypeController : ControllerBase
     {
+        public JumpTypeController(IJumpTypeService jumpTypeService)
+        {
+            _jumpTypeService = jumpTypeService;
+        }
+
         // GET: api/JumpType
         [HttpGet]
         public IEnumerable<JumpTypeResp> Get()
@@ -42,5 +49,7 @@ namespace skydiveLogs_api.Controllers
         public void Delete(int id)
         {
         }
+
+        private readonly IJumpTypeService _jumpTypeService;
     }
 }
diff --git a/Back/skydiveLogs-api/DataContract/AircraftReq.cs b/Back/skydiveLogs-api/DataContract/AircraftReq.cs
new file mode 100644
index 0000000..f205214
--- /dev/null
+++ b/Back/skydiveLogs-api/DataContract/AircraftReq.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace skydiveLogs_api.DataContract
+{
+    public class AircraftReq
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api/DataContract/AircraftResp.cs b/Back/skydiveLogs-api/DataContract/AircraftResp.cs
new file mode 100644
index 0000000..b0b4b3b
--- /dev/null
+++ b/Back/skydiveLogs-api/DataContract/AircraftResp.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace skydiveLogs_api.DataContract
+{
+    public class AircraftResp
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api/DataContract/JumpReq.cs b/Back/skydiveLogs-api/DataContract/JumpReq.cs
new file mode 100644
index 0000000..63da3b8
--- /dev/null
+++ b/Back/skydiveLogs-api/DataContract/JumpReq.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace skydiveLogs_api.DataContract
+{
+    public class JumpReq
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api/DataContract/JumpResp.cs b/Back/skydiveLogs-api/DataContract/JumpResp.cs
new file mode 100644
index 0000000..ed2f730
--- /dev/null
+++ b/Back/skydiveLogs-api/DataContract/JumpResp.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace skydiveLogs_api.DataContract
+{
+    public class JumpResp
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api/DataContract/JumpTypeReq.cs b/Back/skydiveLogs-api/DataContract/JumpTypeReq.cs
new file mode 100644
index 0000000..3533915
--- /dev/null
+++ b/Back/skydiveLogs-api/DataContract/JumpTypeReq.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace skydiveLogs_api.DataContract
+{
+    public class JumpTypeReq
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api/DataContract/JumpTypeResp.cs b/Back/skydiveLogs-api/DataContract/JumpTypeResp.cs
new file mode 100644
index 0000000..68b4f34
--- /dev/null
+++ b/Back/skydiveLogs-api/DataContract/JumpTypeResp.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace skydiveLogs_api.DataContract
+{
+    public class JumpTypeResp
+    {
+    }
+}
diff --git a/Back/skydiveLogs-api/Program.cs b/Back/skydiveLogs-api/Program.cs
index c256952..54e7382 100644
--- a/Back/skydiveLogs-api/Program.cs
+++ b/Back/skydiveLogs-api/Program.cs
@@ -1,12 +1,5 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore;
+using Microsoft.AspNetCore;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.Logging;
 
 namespace skydiveLogs_api
 {
@@ -18,7 +11,6 @@ namespace skydiveLogs_api
         }
 
         public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
-            WebHost.CreateDefaultBuilder(args)
-                .UseStartup<Startup>();
+            WebHost.CreateDefaultBuilder(args).UseStartup<Startup>();
     }
 }
diff --git a/Back/skydiveLogs-api/Startup.cs b/Back/skydiveLogs-api/Startup.cs
index b27a628..d395621 100644
--- a/Back/skydiveLogs-api/Startup.cs
+++ b/Back/skydiveLogs-api/Startup.cs
@@ -1,15 +1,8 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.AspNetCore.HttpsPolicy;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
 
 namespace skydiveLogs_api
 {
@@ -26,6 +19,16 @@ namespace skydiveLogs_api
         public void ConfigureServices(IServiceCollection services)
         {
             services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
+
+            // IoC
+            //services.AddSingleton<IConfigurationRoot>(Configuration);
+            //services.AddSingleton<Services.IGroupService, Services.GroupService>();
+            //services.AddSingleton<Services.IUserService, Services.UserService>();
+            //services.AddSingleton<Services.IPermissionService, Services.PermissionService>();
+
+            //services.AddScoped<Builder.IBuilderVmGroup, Builder.BuilderVmGroup>();
+            //services.AddScoped<Builder.IBuilderVmUser, Builder.BuilderVmUser>();
+            //services.AddScoped<Builder.IBuilderVmPermission, Builder.BuilderVmPermission>();
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.