diff --git a/src/App.tsx b/src/App.tsx
index 81e011f432..6b686f2d49 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -1,26 +1,170 @@
-/* eslint-disable max-len */
+/* eslint-disable jsx-a11y/label-has-associated-control */
 /* eslint-disable jsx-a11y/control-has-associated-label */
-import React from 'react';
-import { UserWarning } from './UserWarning';
+import React, { useEffect, useMemo, useRef, useState } from 'react';
+import * as todoService from './api/todos';
+import { Todo } from './types/Todo';
 
-const USER_ID = 0;
+import { Header } from './components/Header/Header';
+import { Footer } from './components/Footer/Footer';
+import { UserWarning } from './UserWarning';
+import { Errors } from './types/Errors';
+import { ErrorNotification } from './components/ErrorNotification';
+import { FilterType } from './types/FilterType';
+import { TodoList } from './components/TodoList/TodoList';
 
 export const App: React.FC = () => {
-  if (!USER_ID) {
+  const [todos, setTodos] = useState<Todo[]>([]);
+  const [errorMessage, setErrorMessage] = useState<Errors>(Errors.Empty);
+  const [filteredField, setFilteredField] = useState<FilterType>(
+    FilterType.All,
+  );
+  const [tempTodo, setTempTodo] = useState<Todo | null>(null);
+  const [loadingTodoIds, setLoadingTodoIds] = useState<number[]>([]);
+  const inputAddRef = useRef<HTMLInputElement>(null);
+
+  const todosActiveNumber = useMemo(() => {
+    return todos.filter(todo => !todo.completed).length;
+  }, [todos]);
+
+  const areAllTodosCompleted = useMemo(() => {
+    return todos.every(todo => todo.completed === true);
+  }, [todos]);
+
+  useEffect(() => {
+    (async () => {
+      try {
+        const data = await todoService.getTodos();
+
+        setTodos(data);
+      } catch (err) {
+        setErrorMessage(Errors.UnableToLoad);
+      }
+    })();
+  }, []);
+
+  const onAddTodo = async (todoTitle: string) => {
+    setTempTodo({
+      id: 0,
+      title: todoTitle,
+      completed: false,
+      userId: todoService.USER_ID,
+    });
+    try {
+      const newTodo = await todoService.addTodo({
+        title: todoTitle,
+        completed: false,
+      });
+
+      setTodos(prev => [...prev, newTodo]);
+    } catch (err) {
+      setErrorMessage(Errors.UnableToAdd);
+      inputAddRef?.current?.focus();
+      throw err;
+    } finally {
+      setTempTodo(null);
+    }
+  };
+
+  const onRemoveTodo = async (todoId: number) => {
+    setLoadingTodoIds(prev => [...prev, todoId]);
+    try {
+      await todoService.deleteTodo(todoId);
+
+      setTodos(prev => prev.filter(todo => todo.id !== todoId));
+    } catch (err) {
+      setErrorMessage(Errors.UnableToDelete);
+      inputAddRef?.current?.focus();
+      throw err;
+    } finally {
+      setLoadingTodoIds(prev => prev.filter(id => id !== todoId));
+    }
+  };
+
+  const onUpdateTodo = async (todoToUpdate: Todo) => {
+    setLoadingTodoIds(prev => [...prev, todoToUpdate.id]);
+    try {
+      const updatedTodo = await todoService.updateTodo(todoToUpdate);
+
+      setTodos(prev =>
+        prev.map(todo => (todo.id === updatedTodo.id ? updatedTodo : todo)),
+      );
+    } catch (err) {
+      setErrorMessage(Errors.UnableToUpdate);
+      throw err;
+    } finally {
+      setLoadingTodoIds(prev => prev.filter(id => id !== todoToUpdate.id));
+    }
+  };
+
+  const onToggleAll = async () => {
+    if (todosActiveNumber > 0) {
+      todos
+        .filter(todo => !todo.completed)
+        .forEach(item => onUpdateTodo({ ...item, completed: true }));
+    } else {
+      todos.forEach(todo => onUpdateTodo({ ...todo, completed: false }));
+    }
+  };
+
+  const onClearCompleted = async () => {
+    const completedTodo = todos.filter(todo => todo.completed);
+
+    completedTodo.forEach(todo => onRemoveTodo(todo.id));
+  };
+
+  const filteredTodos = todos.filter(todo => {
+    switch (filteredField) {
+      case FilterType.Active:
+        return !todo.completed;
+      case FilterType.Completed:
+        return todo.completed;
+      default:
+        return todos;
+    }
+  });
+
+  if (!todoService.USER_ID) {
     return <UserWarning />;
   }
 
   return (
-    <section className="section container">
-      <p className="title is-4">
-        Copy all you need from the prev task:
-        <br />
-        <a href="https://github.com/mate-academy/react_todo-app-add-and-delete#react-todo-app-add-and-delete">
-          React Todo App - Add and Delete
-        </a>
-      </p>
-
-      <p className="subtitle">Styles are already copied</p>
-    </section>
+    <div className="todoapp">
+      <h1 className="todoapp__title">todos</h1>
+
+      <div className="todoapp__content">
+        <Header
+          setErrorMessage={setErrorMessage}
+          onAddTodo={onAddTodo}
+          isInputDisabled={!!tempTodo}
+          onToggleAll={onToggleAll}
+          todosLength={todos.length}
+          inputRef={inputAddRef}
+          areAllTodosCompleted={areAllTodosCompleted}
+        />
+
+        {(todos.length > 0 || tempTodo) && (
+          <>
+            <TodoList
+              todos={filteredTodos}
+              onRemoveTodo={onRemoveTodo}
+              onUpdateTodo={onUpdateTodo}
+              loadingTodoIds={loadingTodoIds}
+              tempTodo={tempTodo}
+            />
+            <Footer
+              todos={todos}
+              filteredField={filteredField}
+              setFilteredField={setFilteredField}
+              activeTodo={todosActiveNumber}
+              onClearCompleted={onClearCompleted}
+            />
+          </>
+        )}
+      </div>
+      <ErrorNotification
+        error={errorMessage}
+        setErrorMessage={setErrorMessage}
+      />
+    </div>
   );
 };
diff --git a/src/api/todos.ts b/src/api/todos.ts
new file mode 100644
index 0000000000..0100558efb
--- /dev/null
+++ b/src/api/todos.ts
@@ -0,0 +1,20 @@
+import { Todo } from '../types/Todo';
+import { client } from '../utils/fetchClient';
+
+export const USER_ID = 2136;
+
+export const getTodos = () => {
+  return client.get<Todo[]>(`/todos?userId=${USER_ID}`);
+};
+
+export const deleteTodo = (todoId: number) => {
+  return client.delete(`/todos/${todoId}`);
+};
+
+export const addTodo = (newTodo: Omit<Todo, 'id' | 'userId'>) => {
+  return client.post<Todo>('/todos', { ...newTodo, userId: USER_ID });
+};
+
+export function updateTodo(todo: Todo) {
+  return client.patch<Todo>(`/todos/${todo.id}`, todo);
+}
diff --git a/src/components/ErrorNotification/ErrorNotification.tsx b/src/components/ErrorNotification/ErrorNotification.tsx
new file mode 100644
index 0000000000..af8d3eeef9
--- /dev/null
+++ b/src/components/ErrorNotification/ErrorNotification.tsx
@@ -0,0 +1,43 @@
+import classNames from 'classnames';
+import { Errors } from '../../types/Errors';
+import { Dispatch, SetStateAction, useEffect } from 'react';
+
+type Props = {
+  error: Errors;
+  setErrorMessage: Dispatch<SetStateAction<Errors>>;
+};
+export const ErrorNotification: React.FC<Props> = props => {
+  const { error, setErrorMessage } = props;
+
+  useEffect(() => {
+    if (error === Errors.Empty) {
+      return;
+    }
+
+    const timerId = setTimeout(() => {
+      setErrorMessage(Errors.Empty);
+    }, 3000);
+
+    return () => {
+      clearTimeout(timerId);
+    };
+  }, [error, setErrorMessage]);
+
+  return (
+    <div
+      data-cy="ErrorNotification"
+      className={classNames(
+        'notification is-danger is-light has-text-weight-normal',
+        { hidden: !error.length },
+      )}
+    >
+      <button
+        data-cy="HideErrorButton"
+        type="button"
+        className="delete"
+        onClick={() => setErrorMessage(Errors.Empty)}
+      />
+      {error}
+    </div>
+  );
+};
diff --git a/src/components/ErrorNotification/index.ts b/src/components/ErrorNotification/index.ts
new file mode 100644
index 0000000000..8cb4787920
--- /dev/null
+++ b/src/components/ErrorNotification/index.ts
@@ -0,0 +1 @@
+export * from './ErrorNotification';
diff --git a/src/components/Footer/Footer.tsx b/src/components/Footer/Footer.tsx
new file mode 100644
index 0000000000..debe17876d
--- /dev/null
+++ b/src/components/Footer/Footer.tsx
@@ -0,0 +1,55 @@
+import classNames from 'classnames';
+
+import { Dispatch, SetStateAction } from 'react';
+import { Todo } from '../../types/Todo';
+import { FilterType } from '../../types/FilterType';
+
+type Props = {
+  todos: Todo[];
+  activeTodo: number;
+  filteredField: FilterType;
+  setFilteredField: Dispatch<SetStateAction<FilterType>>;
+  onClearCompleted: () => Promise<void>;
+};
+
+export const Footer: React.FC<Props> = ({
+  todos,
+  activeTodo,
+  filteredField,
+  setFilteredField,
+  onClearCompleted,
+}) => {
+  return (
+    <footer className="todoapp__footer" data-cy="Footer">
+      <span className="todo-count" data-cy="TodosCounter">
+        {activeTodo} items left
+      </span>
+
+      <nav className="filter" data-cy="Filter">
+        {Object.values(FilterType).map(filter => (
+          <a
+            key={filter}
+            href={`#/${filter === FilterType.All ? '' : filter.toLowerCase()}`}
+            className={classNames('filter__link', {
+              selected: filteredField === filter,
+            })}
+            data-cy={`FilterLink${filter}`}
+            onClick={() => setFilteredField(filter)}
+          >
+            {filter}
+          </a>
+        ))}
+      </nav>
+
+      <button
+        type="button"
+        className="todoapp__clear-completed"
+        data-cy="ClearCompletedButton"
+        disabled={todos.every(todo => !todo.completed)}
+        onClick={onClearCompleted}
+      >
+        Clear completed
+      </button>
+    </footer>
+  );
+};
diff --git a/src/components/Header/Header.tsx b/src/components/Header/Header.tsx
new file mode 100644
index 0000000000..dfd0eaf4c7
--- /dev/null
+++ b/src/components/Header/Header.tsx
@@ -0,0 +1,81 @@
+import React, { Dispatch, SetStateAction, useEffect, useState } from 'react';
+import cn from 'classnames';
+import { Errors } from '../../types/Errors';
+
+type Props = {
+  setErrorMessage: Dispatch<SetStateAction<Errors>>;
+  onAddTodo: (value: string) => Promise<void>;
+  isInputDisabled: boolean;
+  onToggleAll: () => Promise<void>;
+  todosLength: number;
+  inputRef: React.RefObject<HTMLInputElement> | null;
+  areAllTodosCompleted: boolean;
+};
+
+export const Header: React.FC<Props> = props => {
+  const {
+    setErrorMessage,
+    onAddTodo,
+    isInputDisabled,
+    onToggleAll,
+    todosLength,
+    inputRef,
+    areAllTodosCompleted,
+  } = props;
+  const [inputValue, setInputValue] = useState('');
+
+  const onSubmit = async (event: React.FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+
+    if (inputValue.trim() === '') {
+      setErrorMessage(Errors.EmptyTitle);
+
+      return;
+    }
+
+    try {
+      await onAddTodo(inputValue.trim());
+      setInputValue('');
+    } catch (err) {}
+  };
+
+  useEffect(() => {
+    inputRef?.current?.focus();
+  }, [todosLength, inputRef]);
+
+  useEffect(() => {
+    if (!isInputDisabled) {
+      inputRef?.current?.focus();
+    }
+  }, [isInputDisabled, inputRef]);
+
+  return (
+    <header className="todoapp__header">
+      {todosLength !== 0 && (
+        <button
+          type="button"
+          className={cn('todoapp__toggle-all', {
+            active: areAllTodosCompleted,
+          })}
+          data-cy="ToggleAllButton"
+          onClick={onToggleAll}
+        />
+      )}
+
+      <form onSubmit={onSubmit}>
+        <input
+          data-cy="NewTodoField"
+          type="text"
+          className="todoapp__new-todo"
+          placeholder="What needs to be done?"
+          ref={inputRef}
+          value={inputValue}
+          onChange={event => {
+            setInputValue(event.target.value);
+          }}
+          disabled={isInputDisabled}
+        />
+      </form>
+    </header>
+  );
+};
diff --git a/src/components/TodoItem/TodoItem.tsx b/src/components/TodoItem/TodoItem.tsx
new file mode 100644
index 0000000000..e54423a587
--- /dev/null
+++ b/src/components/TodoItem/TodoItem.tsx
@@ -0,0 +1,123 @@
+import cn from 'classnames';
+import { Todo } from '../../types/Todo';
+import { Dispatch, SetStateAction, useRef, useState } from 'react';
+import { SubmitFormEvent } from '../../types/htmlFormElements';
+
+type Props = {
+  isLoading?: boolean;
+  todo: Todo;
+  onRemoveTodo: (todoId: number) => Promise<void>;
+  onUpdateTodo: (todo: Todo) => Promise<void>;
+  isInEditMode?: boolean;
+  setEditedTodoId: Dispatch<SetStateAction<number | null>>;
+};
+
+export const TodoItem: React.FC<Props> = ({
+  todo,
+  isLoading,
+  onRemoveTodo,
+  onUpdateTodo,
+  isInEditMode,
+  setEditedTodoId,
+}) => {
+  const [todoTitleValue, setTodoTitleValue] = useState(todo.title);
+
+  const inputRef = useRef<HTMLInputElement>(null);
+
+  const onCheckTodo = () => {
+    const todoToUpdate = { ...todo, completed: !todo.completed };
+
+    onUpdateTodo(todoToUpdate);
+  };
+
+  const onDoubleClick = () => {
+    setEditedTodoId(todo.id);
+  };
+
+  const onBlur = async (event: SubmitFormEvent) => {
+    event.preventDefault();
+
+    const normalizedTitle = todoTitleValue.trim();
+
+    if (normalizedTitle === todo.title) {
+      setEditedTodoId(null);
+
+      return;
+    }
+
+    try {
+      if (normalizedTitle === '') {
+        await onRemoveTodo(todo.id);
+      } else {
+        await onUpdateTodo({ ...todo, title: todoTitleValue.trim() });
+      }
+
+      setEditedTodoId(null);
+    } catch (err) {
+      inputRef?.current?.focus();
+    }
+  };
+
+  const onKeyUp = (event: React.KeyboardEvent<HTMLInputElement>) => {
+    if (event.key === 'Escape') {
+      setEditedTodoId(null);
+      setTodoTitleValue(todo.title);
+    }
+  };
+
+  return (
+    <div data-cy="Todo" className={cn('todo', { completed: todo.completed })}>
+      {/* eslint-disable-next-line jsx-a11y/label-has-associated-control */}
+      <label className="todo__status-label">
+        <input
+          data-cy="TodoStatus"
+          type="checkbox"
+          className="todo__status"
+          checked={todo.completed}
+          onChange={onCheckTodo}
+        />
+      </label>
+      {isInEditMode ? (
+        <form onSubmit={onBlur} onBlur={onBlur}>
+          <input
+            autoFocus
+            data-cy="TodoTitleField"
+            type="text"
+            className="todo__title-field"
+            placeholder="Empty todo will be deleted"
+            value={todoTitleValue}
+            onChange={event => setTodoTitleValue(event?.target.value)}
+            onKeyUp={onKeyUp}
+            ref={inputRef}
+          />
+        </form>
+      ) : (
+        <>
+          <span
+            data-cy="TodoTitle"
+            className="todo__title"
+            onDoubleClick={onDoubleClick}
+          >
+            {todo.title}
+          </span>
+          <button
+            type="button"
+            className="todo__remove"
+            data-cy="TodoDelete"
+            onClick={() => onRemoveTodo(todo.id)}
+          >
+            ×
+          </button>
+        </>
+      )}
+
+      <div
+        data-cy="TodoLoader"
+        className={cn('modal overlay', { 'is-active': isLoading })}
+      >
+        <div className="modal-background has-background-white-ter" />
+        <div className="loader" />
+      </div>
+    </div>
+  );
+};
diff --git a/src/components/TodoList/TodoList.tsx b/src/components/TodoList/TodoList.tsx
new file mode 100644
index 0000000000..490cbad71f
--- /dev/null
+++ b/src/components/TodoList/TodoList.tsx
@@ -0,0 +1,54 @@
+import React, { useState } from 'react';
+import { TodoItem } from '../TodoItem/TodoItem';
+import { Todo } from '../../types/Todo';
+import { CSSTransition, TransitionGroup } from 'react-transition-group';
+
+type Props = {
+  isLoading?: boolean;
+  todos: Todo[];
+  onRemoveTodo: (todoId: number) => Promise<void>;
+  onUpdateTodo: (todo: Todo) => Promise<void>;
+  tempTodo: Todo | null;
+  loadingTodoIds: number[];
+};
+
+export const TodoList: React.FC<Props> = ({
+  todos,
+  onRemoveTodo,
+  onUpdateTodo,
+  tempTodo,
+  loadingTodoIds,
+}) => {
+  const [editedTodoId, setEditedTodoId] = useState<number | null>(null);
+
+  return (
+    <TransitionGroup>
+      <section className="todoapp__main" data-cy="TodoList">
+        {todos.map(todo => (
+          <CSSTransition key={todo.id} timeout={300} classNames="item">
+            <TodoItem
+              key={todo.id}
+              todo={todo}
+              onRemoveTodo={onRemoveTodo}
+              onUpdateTodo={onUpdateTodo}
+              isLoading={loadingTodoIds.includes(todo.id)}
+              isInEditMode={editedTodoId === todo.id}
+              setEditedTodoId={setEditedTodoId}
+            />
+          </CSSTransition>
+        ))}
+        {tempTodo && (
+          <CSSTransition key={0} timeout={300} classNames="temp-item">
+            <TodoItem
+              todo={tempTodo}
+              onRemoveTodo={onRemoveTodo}
+              onUpdateTodo={onUpdateTodo}
+              setEditedTodoId={setEditedTodoId}
+              isLoading
+            />
+          </CSSTransition>
+        )}
+      </section>
+    </TransitionGroup>
+  );
+};
diff --git a/src/styles/index.scss b/src/styles/index.scss
index bccd80c8bc..f2f19f4f7f 100644
--- a/src/styles/index.scss
+++ b/src/styles/index.scss
@@ -23,3 +23,50 @@ body {
 @import "./todoapp";
 @import "./todo";
 @import "./filter";
+
+.item-enter {
+  max-height: 0;
+}
+
+.item-enter-active {
+  overflow: hidden;
+  max-height: 58px;
+  transition: max-height 0.3s ease-in-out;
+}
+
+.item-exit {
+  max-height: 58px;
+}
+
+.item-exit-active {
+  overflow: hidden;
+  max-height: 0;
+  transition: max-height 0.3s ease-in-out;
+}
+
+.temp-item-enter {
+  max-height: 0;
+}
+
+.temp-item-enter-active {
+  overflow: hidden;
+  max-height: 58px;
+  transition: max-height 0.3s ease-in-out;
+}
+
+.temp-item-exit {
+  max-height: 58px;
+}
+
+.temp-item-exit-active {
+  transform: translateY(-58px);
+  max-height: 0;
+  opacity: 0;
+  transition: 0.3s ease-in-out;
+  transition-property: opacity, max-height, transform;
+}
+
+.has-error .temp-item-exit-active {
+  transform: translateY(0);
+  overflow: hidden;
+}
diff --git a/src/types/Errors.ts b/src/types/Errors.ts
new file mode 100644
index 0000000000..b0f28f9f6d
--- /dev/null
+++ b/src/types/Errors.ts
@@ -0,0 +1,8 @@
+export enum Errors {
+  Empty = '',
+  UnableToLoad = 'Unable to load todos',
+  EmptyTitle = 'Title should not be empty',
+  UnableToAdd = 'Unable to add a todo',
+  UnableToDelete = 'Unable to delete a todo',
+  UnableToUpdate = 'Unable to update a todo',
+}
diff --git a/src/types/FilterType.ts b/src/types/FilterType.ts
new file mode 100644
index 0000000000..1c3630f736
--- /dev/null
+++ b/src/types/FilterType.ts
@@ -0,0 +1,5 @@
+export enum FilterType {
+  Completed = 'Completed',
+  Active = 'Active',
+  All = 'All',
+}
diff --git a/src/types/Todo.ts b/src/types/Todo.ts
new file mode 100644
index 0000000000..3f52a5fdde
--- /dev/null
+++ b/src/types/Todo.ts
@@ -0,0 +1,6 @@
+export interface Todo {
+  id: number;
+  userId: number;
+  title: string;
+  completed: boolean;
+}
diff --git a/src/types/htmlFormElements.ts b/src/types/htmlFormElements.ts
new file mode 100644
index 0000000000..63e88781e2
--- /dev/null
+++ b/src/types/htmlFormElements.ts
@@ -0,0 +1,3 @@
+export type SubmitFormEvent =
+  | React.FocusEvent<HTMLFormElement, Element>
+  | React.FormEvent<HTMLFormElement>;
diff --git a/src/types/rest.tsx b/src/types/rest.tsx
new file mode 100644
index 0000000000..a94f5bb8c6
--- /dev/null
+++ b/src/types/rest.tsx
@@ -0,0 +1,80 @@
+// const updateTodo = (itemId, updatedTitle) => {
+//   const unmodifiedTodo = todos.find(todo => todo.id === itemId);
+
+//   if (!unmodifiedTodo) {
+//     endChaning(itemId);
+
+//     return;
+//   }
+
+//   if (updatedTitle === unmodifiedTodo.title) {
+//     return;
+//   }
+
+//   const updatedTodo = {
+//     ...unmodifiedTodo,
+//     title: updatedTitle !== null ? updatedTitle.trim() : unmodifiedTodo.title,
+//     completed:
+//       updatedTitle === null
+//         ? !unmodifiedTodo.completed
+//         : unmodifiedTodo.completed,
+//   };
+
+//   if (updatedTitle !== null && updatedTodo.title === '') {
+//     return deleteTodo(itemId);
+//   }
+
+//   setTodos(prev =>
+//     prev.map(todo => (todo.id === itemId ? updatedTodo : todo)),
+//   );
+
+//   return todoService
+//     .updateTodo(updateTodo)
+//     .then(res =>
+//       setTodos(prev => prev.map(todo => (todo.id === itemId ? res : todo))),
+//     )
+//     .catch(err => {
+//       setTodos(prev =>
+//         prev.map(todo => (todo.id === itemId ? unmodifiedTodo : todo)),
+//       );
+//       showErrorMes('Unable to update a todo');
+//       throw err;
+//     })
+//     .finally(() => endChaning(itemId));
+// };
+
+// const clearComleted = () => {
+//   const completedIds = todos
+//     .filter(todo => todo.completed)
+//     .map(todo => todo.id);
+
+//   completedIds.forEach(id => deleteTodo(id));
+// };
+
+// function updateTodo(todoToUpdate: Todo) {
+//   postService.updateTodo(todoToUpdate).then(updatedTodo => {
+//     setSelectedTodo(null);
+
+//     setTodos(currentTodos => {
+//       return currentTodos.map(todo =>
+//         todo.id === updatedTodo.id ? updatedTodo : todo,
+//       );
+//     });
+//   });
+// }
+
+// function updatePost(postToUpdate: Post) {
+//   setErrorMessage('');
+
+//   return postService.updatePost(postToUpdate)
+//     .then(updatedPost => {
+//       setSelectedPost(null);
+
+//       setPosts(currentPosts => {
+//         return currentPosts.map(post =>
+//           post.id === updatedPost.id ? updatedPost : post,
+//         );
+//       });
+//     })
+//     .catch(() => setErrorMessage('Failed to update post'));
+// }
diff --git a/src/utils/fetchClient.ts b/src/utils/fetchClient.ts
new file mode 100644
index 0000000000..708ac4c17b
--- /dev/null
+++ b/src/utils/fetchClient.ts
@@ -0,0 +1,46 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+const BASE_URL = 'https://mate.academy/students-api';
+
+// returns a promise resolved after a given delay
+function wait(delay: number) {
+  return new Promise(resolve => {
+    setTimeout(resolve, delay);
+  });
+}
+
+// To have autocompletion and avoid mistypes
+type RequestMethod = 'GET' | 'POST' | 'PATCH' | 'DELETE';
+
+function request<T>(
+  url: string,
+  method: RequestMethod = 'GET',
+  data: any = null, // we can send any data to the server
+): Promise<T> {
+  const options: RequestInit = { method };
+
+  if (data) {
+    // We add body and Content-Type only for the requests with data
+    options.body = JSON.stringify(data);
+    options.headers = {
+      'Content-Type': 'application/json; charset=UTF-8',
+    };
+  }
+
+  // DON'T change the delay it is required for tests
+  return wait(100)
+    .then(() => fetch(BASE_URL + url, options))
+    .then(response => {
+      if (!response.ok) {
+        throw new Error();
+      }
+
+      return response.json();
+    });
+}
+
+export const client = {
+  get: <T>(url: string) => request<T>(url),
+  post: <T>(url: string, data: any) => request<T>(url, 'POST', data),
+  patch: <T>(url: string, data: any) => request<T>(url, 'PATCH', data),
+  delete: (url: string) => request(url, 'DELETE'),
+};