diff --git a/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IPostBusinessLogicContract.cs b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IPostBusinessLogicContract.cs
new file mode 100644
index 0000000..53e2978
--- /dev/null
+++ b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IPostBusinessLogicContract.cs
@@ -0,0 +1,20 @@
+using North_Bridge_Contract.DataModels;
+
+namespace North_Bridge_Contract.BusinessLogicsContracts;
+
+public interface IPostBusinessLogicContract
+{
+    List<PostDataModel> GetAllPosts(bool onlyActive);
+    
+    List<PostDataModel> GetAllDataOfPost(string postId);
+    
+    PostDataModel GetPostByData(string data);
+    
+    void InsertPost(PostDataModel postDataModel);
+    
+    void UpdatePost(PostDataModel postDataModel);
+    
+    void DeletePost(string id);
+    
+    void RestorePost(string id);
+}
\ No newline at end of file
diff --git a/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IProductBusinessLogicContract.cs b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IProductBusinessLogicContract.cs
new file mode 100644
index 0000000..b3e11fb
--- /dev/null
+++ b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IProductBusinessLogicContract.cs
@@ -0,0 +1,18 @@
+using North_Bridge_Contract.DataModels;
+
+namespace North_Bridge_Contract.BusinessLogicsContracts;
+
+public interface IProductBusinessLogicContract
+{
+    List<ProductDataModel> GetAllProducts(bool onlyActive = true);
+    
+    List<ProductHistoryDataModel> GetProductHistoryByProduct(string productId);
+    
+    ProductDataModel GetProductByData(string data);
+    
+    void InsertProduct(ProductDataModel productDataModel);
+    
+    void UpdateProduct(ProductDataModel productDataModel);
+    
+    void DeleteProduct(string id);
+}
\ No newline at end of file
diff --git a/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/ISalaryBusinessLogicContract.cs b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/ISalaryBusinessLogicContract.cs
new file mode 100644
index 0000000..e32afe9
--- /dev/null
+++ b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/ISalaryBusinessLogicContract.cs
@@ -0,0 +1,12 @@
+using North_Bridge_Contract.DataModels;
+
+namespace North_Bridge_Contract.BusinessLogicsContracts;
+
+public interface ISalaryBusinessLogicContract
+{
+    List<SalaryDataModel> GetAllSalariesByPeriod(DateTime fromDate, DateTime toDate);
+
+    List<SalaryDataModel> GetAllSalariesByPeriodByWorker(DateTime fromDate, DateTime toDate, string workerId);
+
+    void CalculateSalaryByMounth(DateTime date);
+}
\ No newline at end of file
diff --git a/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/ISaleBusinessLogicContract.cs b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/ISaleBusinessLogicContract.cs
new file mode 100644
index 0000000..717a82a
--- /dev/null
+++ b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/ISaleBusinessLogicContract.cs
@@ -0,0 +1,18 @@
+using North_Bridge_Contract.DataModels;
+
+namespace North_Bridge_Contract.BusinessLogicsContracts;
+
+public interface ISaleBusinessLogicContract
+{
+    List<SaleDataModel> GetAllSalesByPeriod(DateTime fromDate, DateTime toDate);
+    
+    List<SaleDataModel> GetAllSalesByWorkerByPeriod(string workerId, DateTime fromDate, DateTime toDate);
+    
+    List<SaleDataModel> GetAllSalesByProductByPeriod(string productId, DateTime fromDate, DateTime toDate);
+    
+    SaleDataModel GetSaleByData(string data);
+    
+    void InsertSale(SaleDataModel saleDataModel);
+    
+    void CancelSale(string id);
+}
\ No newline at end of file
diff --git a/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IWorkerBusinessLogicContract.cs b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IWorkerBusinessLogicContract.cs
new file mode 100644
index 0000000..1a89ff4
--- /dev/null
+++ b/North_Bridge/North_Bridge_Contract/BusinessLogicsContracts/IWorkerBusinessLogicContract.cs
@@ -0,0 +1,27 @@
+using North_Bridge_Contract.DataModels;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace North_Bridge_Contract.BusinessLogicsContracts;
+
+public interface IWorkerBusinessLogicContract
+{
+    List<WorkerDataModel> GetAllWorkers(bool onlyActive = true);
+    
+    List<WorkerDataModel> GetAllWorkersByPost(string postId, bool onlyActive = true);
+    
+    List<WorkerDataModel> GetAllWorkersByBirthDate(DateTime fromDate, DateTime toDate, bool onlyActive = true);
+    
+    List<WorkerDataModel> GetAllWorkersByEmploymentDate(DateTime fromDate, DateTime toDate, bool onlyActive = true);
+    
+    WorkerDataModel GetWorkerByData(string data);
+    
+    void InsertWorker(WorkerDataModel workerDataModel);
+    
+    void UpdateWorker(WorkerDataModel workerDataModel);
+    
+    void DeleteWorker(string id);
+}
\ No newline at end of file