diff --git a/UP01Task2App/UP01Task2App/Models/Client.cs b/UP01Task2App/UP01Task2App/Models/Client.cs
new file mode 100644
index 0000000..81ad5ed
--- /dev/null
+++ b/UP01Task2App/UP01Task2App/Models/Client.cs
@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace UP01Task2App.Models
+{
+    public class Client
+    {
+        public string Surname { get; set; }
+        public string Name { get; set; }
+        public string Patronymic { get; set; } 
+        public DateTime? BirthDate { get; set; }
+        public string Adress { get; set; }
+        public string PhoneNumber { get; set; }
+        public int SubscriptionNumber { get; set; }
+
+        public override string ToString()
+        {
+            return Surname + " " + Name + " " + Patronymic;
+        }
+    }
+}
diff --git a/UP01Task2App/UP01Task2App/Models/Record.cs b/UP01Task2App/UP01Task2App/Models/Record.cs
new file mode 100644
index 0000000..51625b8
--- /dev/null
+++ b/UP01Task2App/UP01Task2App/Models/Record.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace UP01Task2App.Models
+{
+    public class Record
+    {
+        public Client Client { get; set; }
+        public Trainer Trainer { get; set; }
+        DateOnly RecordDate { set; get; }
+        TimeOnly RecordTime {  set; get; }
+    }
+}
diff --git a/UP01Task2App/UP01Task2App/Models/Trainer.cs b/UP01Task2App/UP01Task2App/Models/Trainer.cs
new file mode 100644
index 0000000..a3fa35b
--- /dev/null
+++ b/UP01Task2App/UP01Task2App/Models/Trainer.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace UP01Task2App.Models
+{
+    public class Trainer
+    {
+        public string Surmname { get; set; }
+        public string Name { get; set; }
+        public string Patronymic { get; set; }
+        public string Speciality { get; set; }
+    }
+}
diff --git a/UP01Task2App/UP01Task2App/Services/JsonService.cs b/UP01Task2App/UP01Task2App/Services/JsonService.cs
new file mode 100644
index 0000000..f426a7e
--- /dev/null
+++ b/UP01Task2App/UP01Task2App/Services/JsonService.cs
@@ -0,0 +1,71 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using System.Text.Json;
+using System.Windows;
+using System.Windows.Shapes;
+using UP01Task2App.Models;
+
+namespace UP01Task2App.Services
+{
+    internal class JsonService
+    {
+        private const string trainerPath = "data/trainers.json";
+        private const string clientPath = "data/clients.json";
+        private const string recordPath = "data/records.json";
+
+        private void SaveToJson<T>(string path, List<T> data)
+        {
+            var options = new JsonSerializerOptions
+            {
+                WriteIndented = true
+            };
+
+            try
+            {
+                data ??= new List<T>();
+
+                string json = JsonSerializer.Serialize(data, options);
+
+                string? dir = System.IO.Path.GetDirectoryName(path);
+                if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))
+                    Directory.CreateDirectory(dir);
+
+                File.WriteAllText(path, json, Encoding.UTF8);
+            }
+            catch
+            {
+                throw new ArgumentException("Не удалось сохранить данные");
+            }
+        }
+
+        private List<T> ReadFromJson<T>(string path)
+        {
+            if (!File.Exists(path) || new FileInfo(path).Length == 0)
+                return new List<T>();
+
+            string json = File.ReadAllText(path);
+
+            if (string.IsNullOrWhiteSpace(json))
+                return new List<T>();
+
+            try
+            {
+                return JsonSerializer.Deserialize<List<T>>(json) ?? new List<T>();
+            }
+            catch
+            {
+                return new List<T>();
+            }
+        }
+
+        public List<Trainer> ReadTrainerDataFromJson() => ReadFromJson<Trainer>(trainerPath);
+        public List<Client> ReadClientDataFromJson() => ReadFromJson<Client>(clientPath);
+        public List<Record> ReadRecordDataFromJson() => ReadFromJson<Record>(recordPath);
+
+        public void SaveTrainerDataToJson(List<Trainer> trainersList) => SaveToJson(trainerPath, trainersList);
+        public void SaveClientDataToJson(List<Client> clientsList) => SaveToJson(clientPath, clientsList);
+        public void SaveRecordDataToJson(List<Record> recordsList) => SaveToJson(recordPath, recordsList);
+    }
+}
diff --git a/UP01Task2App/UP01Task2App/Services/ValidationHelper.cs b/UP01Task2App/UP01Task2App/Services/ValidationHelper.cs
new file mode 100644
index 0000000..dba71c7
--- /dev/null
+++ b/UP01Task2App/UP01Task2App/Services/ValidationHelper.cs
@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Windows.Controls;
+
+namespace UP01Task2App.Services
+{
+    public static class ValidationHelper
+    {
+        public static void ValidateNotNullTextBox(TextBox obj, string fieldName)
+        {
+            if (string.IsNullOrWhiteSpace(obj.Text))
+                throw new ArgumentException($"Поле \"{fieldName}\" не должно быть пустым");
+        }
+        public static void ValidateNumTextBox(TextBox obj, string fieldName)
+        {
+            foreach (var c in obj.Text)
+            {
+                if (!char.IsDigit(c))
+                    throw new ArgumentException($"В поле \"{fieldName}\" можно вводить только числа");
+            }
+        }
+        public static void ValidateDateNotInFutureTextBox(DatePicker obj, string fieldName)
+        {
+            if (obj.SelectedDate > DateTime.Now)
+                throw new ArgumentException($"В поле \"{fieldName}\" выбранная дата не может быть в будущем");
+        }
+        public static void ValidateNotNullDatePicker(DatePicker obj, string fieldName)
+        {
+            if (obj.SelectedDate == null)
+                throw new ArgumentException($"Выберите дату в поле \"{fieldName}\"");
+        }
+        public static void ValidateIntRangeTextBox(TextBox obj, string fieldName)
+        {
+            if (!int.TryParse(obj.Text, out int _))
+                throw new ArgumentException($"Введенное число в \"{fieldName}\" слишком большое или маленькое");
+        }
+    }
+}
\ No newline at end of file
diff --git a/UP01Task2App/UP01Task2App/ViewModels/BaseViewModel.cs b/UP01Task2App/UP01Task2App/ViewModels/BaseViewModel.cs
deleted file mode 100644
index 9901540..0000000
--- a/UP01Task2App/UP01Task2App/ViewModels/BaseViewModel.cs
+++ /dev/null
@@ -1,19 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-
-namespace UP01Task2App.ViewModels
-{
-    using System.ComponentModel;
-    using System.Runtime.CompilerServices;
-
-    public class BaseViewModel : INotifyPropertyChanged
-    {
-        public event PropertyChangedEventHandler PropertyChanged;
-
-        protected void OnPropertyChanged([CallerMemberName] string name = null)
-        {
-            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
-        }
-    }
-}
diff --git a/UP01Task2App/UP01Task2App/ViewModels/RelayCommand.cs b/UP01Task2App/UP01Task2App/ViewModels/RelayCommand.cs
deleted file mode 100644
index a8b28e2..0000000
--- a/UP01Task2App/UP01Task2App/ViewModels/RelayCommand.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-using System;
-using System.Windows.Input;
-
-public class RelayCommand : ICommand
-{
-    private readonly Action _execute;
-    private readonly Func<bool> _canExecute;
-
-    public RelayCommand(Action execute, Func<bool> canExecute = null)
-    {
-        _execute = execute;
-        _canExecute = canExecute;
-    }
-
-    public bool CanExecute(object parameter) => _canExecute?.Invoke() ?? true;
-
-    public void Execute(object parameter) => _execute();
-
-    public event EventHandler CanExecuteChanged;
-}
\ No newline at end of file
diff --git a/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml b/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml
index 9bdc2c4..41d504c 100644
--- a/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml
+++ b/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml
@@ -11,32 +11,32 @@
             <StackPanel Orientation="Horizontal">
                 <StackPanel HorizontalAlignment="Left">
                     <TextBlock Text="Фамилия"/>
-                    <TextBox Text="{Binding LastName}" Style="{StaticResource TextBoxStyle}"/>
+                    <TextBox Name="SurnameTextBox" Style="{StaticResource TextBoxStyle}"/>
 
                     <TextBlock Text="Имя"/>
-                    <TextBox Text="{Binding FirstName}" Style="{StaticResource TextBoxStyle}"/>
+                    <TextBox Name="NameTextBox" Style="{StaticResource TextBoxStyle}"/>
 
                     <TextBlock Text="Отчество"/>
-                    <TextBox Text="{Binding MiddleName}" Style="{StaticResource TextBoxStyle}"/>
+                    <TextBox Name="PatronymicTextBox" Style="{StaticResource TextBoxStyle}"/>
 
                     <TextBlock Text="Дата рождения"/>
-                    <DatePicker SelectedDate="{Binding BirthDate}" Style="{StaticResource DatePickerStyle}" />
+                    <DatePicker Name="BirthDateDatePicker" Style="{StaticResource DatePickerStyle}" />
                 </StackPanel>
 
                 <StackPanel HorizontalAlignment="Right" Margin="20,0,0,0">
                     <TextBlock Text="Фактический адрес"/>
-                    <TextBox Text="{Binding Address}" Style="{StaticResource TextBoxStyle}"/>
+                    <TextBox Name="AdressTextBox" Style="{StaticResource TextBoxStyle}"/>
 
                     <TextBlock Text="Телефон"/>
-                    <TextBox Text="{Binding Phone}" Style="{StaticResource TextBoxStyle}"/>
+                    <TextBox Name="PhoneNumberTextBox" Style="{StaticResource TextBoxStyle}"/>
 
                     <TextBlock Text="Номер абонемента"/>
-                    <TextBox Text="{Binding MembershipNumber}" Style="{StaticResource TextBoxStyle}"/>
+                    <TextBox Name="SubscriptionMumberTextBox" Style="{StaticResource TextBoxStyle}"/>
 
                     <TextBlock Text="Пол"/>
                     <StackPanel Orientation="Horizontal" Margin="5">
-                        <RadioButton Content="М" GroupName="rg1"/>
-                        <RadioButton Content="Ж" GroupName="rg1"/>
+                        <RadioButton Name="rbMan" Content="М" GroupName="rg1"/>
+                        <RadioButton Name="rbWoman" Content="Ж" GroupName="rg1"/>
                     </StackPanel>
                 </StackPanel>
             </StackPanel>
@@ -47,33 +47,27 @@
 
             <TextBlock Text="Список клиентов" FontSize="18" Margin="0,0,0,10"/>
 
-            <ListBox ItemsSource="{Binding Clients}" 
-                 SelectedItem="{Binding SelectedClient}"
-                 Height="250"
-                 DisplayMemberPath="LastName"/>
+            <ListBox ItemsSource="{Binding ClientsUI}" 
+                 Height="250"/>
 
             <StackPanel Orientation="Horizontal"
                         Margin="10">
                 <StackPanel>
                     <Button Content="Добавить клиента"
-                        Command="{Binding AddClientCommand}"
                         Style="{StaticResource ButtonStyle}" 
-                        Margin="10"/>
+                        Margin="10" Click="Button_Click"/>
 
                     <Button Content="Изменить клиента"
-                        Command="{Binding EditClientCommand}"
                         Style="{StaticResource ButtonStyle}"
                         Margin="10"/>
                 </StackPanel>
 
                 <StackPanel>
                     <Button Content="Запись клиента"
-                        Command="{Binding AddAppointmentCommand}"
                         Style="{StaticResource ButtonStyle}"
                         Margin="10"/>
 
                     <Button Content="Просмотреть записи"
-                        Command="{Binding ViewAppointmentsCommand}"
                         Style="{StaticResource ButtonStyle}"
                         Margin="10"/>
                 </StackPanel>
diff --git a/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml.cs b/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml.cs
index be46b9a..3733bfd 100644
--- a/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml.cs
+++ b/UP01Task2App/UP01Task2App/Windows/ClientWindow.xaml.cs
@@ -1,6 +1,9 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.IO;
 using System.Text;
+using System.Text.Json;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
@@ -9,6 +12,8 @@ using System.Windows.Input;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using System.Windows.Shapes;
+using UP01Task2App.Models;
+using UP01Task2App.Services;
 
 namespace UP01Task2App.Windows
 {
@@ -17,9 +22,91 @@ namespace UP01Task2App.Windows
     /// </summary>
     public partial class ClientWindow : Window
     {
+        private JsonService Json = new();
+        public List<Client> ClientsList = new();
+        public List<Trainer> TrainersList = new();
+        public List<Record> RecordsList = new();
+
+        public ObservableCollection<Client> ClientsUI { get; set; } = new();
         public ClientWindow()
         {
             InitializeComponent();
+
+            ClientsList = Json.ReadClientDataFromJson();
+            TrainersList = Json.ReadTrainerDataFromJson();
+            RecordsList = Json.ReadRecordDataFromJson();
+
+            UpdateClientUI();
+
+            this.DataContext = this;
+        }
+
+        private void UpdateClientUI()
+        {
+            ClientsUI.Clear();
+            foreach (var item in ClientsList)
+            {
+                ClientsUI.Add(item);
+            }
+        }
+
+        private bool ValidateFields()
+        {
+            try
+            {
+                ValidationHelper.ValidateNotNullTextBox(SurnameTextBox, "Фамилия");
+                ValidationHelper.ValidateNotNullTextBox(NameTextBox, "Имя");
+                ValidationHelper.ValidateNotNullTextBox(PatronymicTextBox, "Отчество");
+                ValidationHelper.ValidateNotNullDatePicker(BirthDateDatePicker, "Дата рождения");
+                ValidationHelper.ValidateDateNotInFutureTextBox(BirthDateDatePicker, "Дата рождения");
+                ValidationHelper.ValidateNotNullTextBox(AdressTextBox, "Фактический адрес");
+                ValidationHelper.ValidateNotNullTextBox(PhoneNumberTextBox, "Телефон");
+                ValidationHelper.ValidateNumTextBox(PhoneNumberTextBox, "Телефон");
+                ValidationHelper.ValidateNotNullTextBox(SubscriptionMumberTextBox, "Номер абонемента");
+                ValidationHelper.ValidateNumTextBox(SubscriptionMumberTextBox, "Номер абонемента");
+                ValidationHelper.ValidateIntRangeTextBox(SubscriptionMumberTextBox, "Номер абонемента");
+
+                if (rbMan.IsChecked == null && rbWoman.IsChecked == null)
+                {
+                    throw new ArgumentException("Выберите пол");
+                }
+
+                return true;
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show(ex.Message);
+                return false;
+            }
+        }
+
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            if (ValidateFields())
+            {
+                ClientsList.Add(new Client
+                {
+                    Surname = SurnameTextBox.Text,
+                    Name = NameTextBox.Text,
+                    Adress = AdressTextBox.Text,
+                    BirthDate = BirthDateDatePicker.SelectedDate,
+                    Patronymic = PatronymicTextBox.Text,
+                    PhoneNumber = PhoneNumberTextBox.Text,
+                    SubscriptionNumber = int.Parse(SubscriptionMumberTextBox.Text)
+                });
+
+                try
+                {
+                    Json.SaveClientDataToJson(ClientsList);
+                    MessageBox.Show("Данные сохранены");
+                }
+                catch (Exception ex)
+                {
+                    MessageBox.Show(ex.Message);
+                }
+
+                UpdateClientUI();
+            }
         }
     }
 }