diff --git a/client/internal/CMakeLists.txt b/client/internal/CMakeLists.txt
index f76cc95852d6c9979711c7956fd08f908d82c92a..790ec143130bef8ba27e526a4f50cdc9e8907cb4 100644
--- a/client/internal/CMakeLists.txt
+++ b/client/internal/CMakeLists.txt
@@ -1,6 +1,7 @@
 add_subdirectory(entities)
 add_subdirectory(httpClient)
 add_subdirectory(gui)
+add_subdirectory(core)
 
 set(libClientEntities_LIB ${libClientEntities_LIB} PARENT_SCOPE)
 set(libClientEntities_INCLUDE_DIRS ${libClientEntities_INCLUDE_DIRS} PARENT_SCOPE)
@@ -9,4 +10,7 @@ set(HTTPCLIENT_lib_LIB ${HTTPCLIENT_lib_LIB} PARENT_SCOPE)
 set(HTTPCLIENT_lib_INCLUDE_DIRS ${HTTPCLIENT_lib_INCLUDE_DIRS} PARENT_SCOPE)
 
 set(GUI_lib_LIB ${GUI_lib_LIB} PARENT_SCOPE)
-set(GUI_lib_INCLUDE_DIRS ${GUI_lib_INCLUDE_DIRS} PARENT_SCOPE)
\ No newline at end of file
+set(GUI_lib_INCLUDE_DIRS ${GUI_lib_INCLUDE_DIRS} PARENT_SCOPE)
+
+set(CORE_lib_LIB ${CORE_lib_LIB} PARENT_SCOPE)
+set(CORE_lib_INCLUDE_DIRS ${CORE_lib_INCLUDE_DIRS} PARENT_SCOPE)
\ No newline at end of file
diff --git a/client/internal/core/CMakeLists.txt b/client/internal/core/CMakeLists.txt
new file mode 100644
index 0000000000000000000000000000000000000000..8a2af6623c90b54e3a1719fd9206b2ebd723306c
--- /dev/null
+++ b/client/internal/core/CMakeLists.txt
@@ -0,0 +1,18 @@
+project("CoreLib")
+
+set(CMAKE_CXX_STANDARD 20)
+
+file(GLOB SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src/*.cpp)
+file(GLOB INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/include)
+file(GLOB INCLUDES ${CMAKE_CURRENT_SOURCE_DIR}/include/*.h)
+
+include_directories(${INCLUDE_DIRS} ${libClientEntities_INCLUDE_DIRS} ${HTTPCLIENT_lib_INCLUDE_DIRS})
+
+add_library(${PROJECT_NAME} ${SOURCES} ${INCLUDES})
+target_link_libraries(${PROJECT_NAME} ${libClientEntities_LIB} ${HTTPCLIENT_lib_LIB})
+
+set(CORE_lib_LIB ${PROJECT_NAME})
+set(CORE_lib_LIB ${CORE_lib_LIB} PARENT_SCOPE)
+
+set(CORE_lib_INCLUDE_DIRS ${INCLUDE_DIRS})
+set(CORE_lib_INCLUDE_DIRS ${CORE_lib_INCLUDE_DIRS} PARENT_SCOPE)
\ No newline at end of file
diff --git a/client/internal/core/include/Core.h b/client/internal/core/include/Core.h
new file mode 100644
index 0000000000000000000000000000000000000000..d88af4de561aba58bb1c97077e1ae5bd0ff44010
--- /dev/null
+++ b/client/internal/core/include/Core.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "Task.h"
+
+class Core {
+public:
+    Core() { user_id = -1; };
+
+    static unsigned signUp(const std::string &login, const std::string &username, const std::string &pass);
+
+    static unsigned login(const std::string &login, const std::string &pass);
+
+    static void logout();
+
+private:
+    static std::size_t user_id;
+};
diff --git a/client/internal/core/src/Core.cpp b/client/internal/core/src/Core.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..bf3d43dbd11bf0eb2b29af5fa71cb8bff771483b
--- /dev/null
+++ b/client/internal/core/src/Core.cpp
@@ -0,0 +1,26 @@
+//
+// Created by Николай Степанов on 11.05.2023.
+//
+#include "Core.h"
+#include "HttpClientManager.h"
+
+const std::string CLIENT_IP = "0.0.0.0";
+const std::string CLIENT_PORT = "80";
+HttpClientManager client(CLIENT_IP, CLIENT_PORT);
+
+unsigned Core::signUp(const std::string &login, const std::string &username, const std::string &pass) {
+    auto res = client.registerUser(login, username, pass);
+    user_id = res.second.id;
+    return res.first;
+}
+
+unsigned Core::login(const std::string &login, const std::string &pass) {
+    auto res = client.loginUser(login, pass);
+    user_id = res.second.id;
+    return res.first;
+}
+
+void Core::logout() {
+    user_id = -1;
+}
+
diff --git a/client/internal/entities/include/Metric.h b/client/internal/entities/include/Metric.h
index 3ab8ea715cfd8be2f766a56b001ce23887c1252a..db320cf9732f1a3b1031e4ff370f717ae99f4ff0 100644
--- a/client/internal/entities/include/Metric.h
+++ b/client/internal/entities/include/Metric.h
@@ -1,5 +1,4 @@
-#ifndef SOURCEDOUT_METRIC_H
-#define SOURCEDOUT_METRIC_H
+#pragma once
 
 #include <string>
 
@@ -7,5 +6,3 @@ struct Metric {
     std::string name;
     unsigned int value;
 };
-
-#endif //SOURCEDOUT_METRIC_H
diff --git a/client/internal/entities/include/Solution.h b/client/internal/entities/include/Solution.h
index 6282f4720c15e6c10825ce75310509585bac04f6..384e648c4b1c3647776396c1a1da467758839748 100644
--- a/client/internal/entities/include/Solution.h
+++ b/client/internal/entities/include/Solution.h
@@ -1,58 +1,10 @@
-#ifndef SOURCEDOUT_SOLUTION_HPP
-#define SOURCEDOUT_SOLUTION_HPP
+#pragma once
 
 #include <iostream>
 #include <string>
 #include <utility>
 
-class Solution {
-public:
-    Solution() =default;
-    Solution(size_t id, std::string sendDate, size_t senderId, std::string source,
-             std::string tokens, std::string astTree, size_t taskId, std::string result);
-
-    [[nodiscard]] size_t getId() const;
-
-
-    [[nodiscard]] const std::string &getSendDate() const;
-
-    void setSendDate(const std::string &sendDate);
-
-    [[nodiscard]] size_t getSenderId() const;
-
-    void setSenderId(size_t senderId);
-
-    [[nodiscard]] const std::string &getSource() const;
-
-    void setSource(const std::string &source);
-
-    [[nodiscard]] const std::string &getTokens() const;
-
-    void setTokens(const std::string &tokens);
-
-    [[nodiscard]] const std::string &getAstTree() const;
-
-    void setAstTree(const std::string &astTree);
-
-    [[nodiscard]] size_t getTaskId() const;
-
-    void setTaskId(size_t taskId);
-
-    [[nodiscard]] const std::string &getResult() const;
-
-    void setResult(const std::string &result);
-
-private:
+struct Solution {
     size_t id;
-    std::string send_date;
-    size_t sender_id;
     std::string source;
-    std::string tokens;
-    std::string astTree;
-    size_t task_id;
-    std::string result;
-public:
-
-};
-
-#endif //SOURCEDOUT_SOLUTION_HPP
\ No newline at end of file
+};
\ No newline at end of file
diff --git a/client/internal/entities/include/Task.h b/client/internal/entities/include/Task.h
index 9d87ca6b44176625da12296a15fcae656aae4dd1..de9c48848fffdc53ce7675dcf5112077f6ecffe9 100644
--- a/client/internal/entities/include/Task.h
+++ b/client/internal/entities/include/Task.h
@@ -1,11 +1,10 @@
-#ifndef SOURCEDOUT_TASK_HPP
-#define SOURCEDOUT_TASK_HPP
+#pragma once
 
 #include <iostream>
 
 struct Task{
     std::size_t id;
     std::string description;
-};
 
-#endif //SOURCEDOUT_TASK_HPP
\ No newline at end of file
+    Task(std::size_t id, std::string_view desc);
+};
diff --git a/client/internal/entities/include/User.h b/client/internal/entities/include/User.h
index 5802df2c3c5291cc7e0b697c71e7e3efdf005b94..94825402abfefa1f9518fd38f9f35389aef7eae7 100644
--- a/client/internal/entities/include/User.h
+++ b/client/internal/entities/include/User.h
@@ -1,38 +1,11 @@
-#ifndef SOURCEDOUT_USER_HPP
+#pragma once
 
 #include <iostream>
 #include <utility>
 
-#define SOURCEDOUT_USER_HPP
-
-class User {
-private:
+struct User {
     size_t id;
     std::string login;
     std::string password;
     std::string username;
-
-public:
-    User()=default;
-    User(size_t id_, std::string login_, std::string password_, std::string username_);
-
-    User(std::string login_, std::string password_, std::string username_);
-
-    [[nodiscard]] const std::string &getLogin() const;
-
-    void setLogin(const std::string &login);
-
-    [[nodiscard]] const std::string &getPassword() const;
-
-    void setPassword(const std::string &password);
-
-    [[nodiscard]] const std::string &getUsername() const;
-
-    void setUsername(const std::string &username);
-
-    [[nodiscard]] size_t getId() const;
-
-    friend std::ostream &operator<<(std::ostream &os, const User &user);
-};
-
-#endif //SOURCEDOUT_USER_HPP
\ No newline at end of file
+};
\ No newline at end of file
diff --git a/client/internal/entities/src/Solution.cpp b/client/internal/entities/src/Solution.cpp
deleted file mode 100644
index 2e9b1e8d60ddb9bb95972ad24d66519cda5b3a92..0000000000000000000000000000000000000000
--- a/client/internal/entities/src/Solution.cpp
+++ /dev/null
@@ -1,73 +0,0 @@
-
-#include <string>
-#include <utility>
-#include "Solution.h"
-
-Solution::Solution(unsigned long id, std::string sendDate, unsigned long senderId,
-                   std::string source, std::string tokens,
-                   std::string astTree, unsigned long taskId,
-                   std::string result) : id(id), send_date(std::move(sendDate)), sender_id(senderId),
-                                         source(std::move(source)), tokens(std::move(tokens)),
-                                         astTree(std::move(astTree)),
-                                         task_id(taskId), result(std::move(result)) {}
-
-size_t Solution::getId() const {
-    return id;
-}
-
-
-const std::string &Solution::getSendDate() const {
-    return send_date;
-}
-
-void Solution::setSendDate(const std::string &sendDate) {
-    send_date = sendDate;
-}
-
-size_t Solution::getSenderId() const {
-    return sender_id;
-}
-
-void Solution::setSenderId(size_t senderId) {
-    sender_id = senderId;
-}
-
-const std::string &Solution::getSource() const {
-    return source;
-}
-
-void Solution::setSource(const std::string &source_) {
-    Solution::source = source_;
-}
-
-const std::string &Solution::getTokens() const {
-    return tokens;
-}
-
-void Solution::setTokens(const std::string &tokens_) {
-    Solution::tokens = tokens_;
-}
-
-const std::string &Solution::getAstTree() const {
-    return astTree;
-}
-
-void Solution::setAstTree(const std::string &astTree_) {
-    Solution::astTree = astTree_;
-}
-
-size_t Solution::getTaskId() const {
-    return task_id;
-}
-
-void Solution::setTaskId(size_t taskId) {
-    task_id = taskId;
-}
-
-const std::string &Solution::getResult() const {
-    return result;
-}
-
-void Solution::setResult(const std::string &result_) {
-    Solution::result = result_;
-}
\ No newline at end of file
diff --git a/client/internal/entities/src/Task.cpp b/client/internal/entities/src/Task.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..496fddceead02a74be19079d28d93bef9641d1e2
--- /dev/null
+++ b/client/internal/entities/src/Task.cpp
@@ -0,0 +1,3 @@
+#include "Task.h"
+
+Task::Task(std::size_t id, std::string_view desc) : id(id), description(desc);
\ No newline at end of file
diff --git a/client/internal/entities/src/User.cpp b/client/internal/entities/src/User.cpp
deleted file mode 100644
index 53706e252495f37340c0f1b8443c2126f8eb87af..0000000000000000000000000000000000000000
--- a/client/internal/entities/src/User.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-#include <iostream>
-#include "User.h"
-
-User::User(size_t id_, std::string login_, std::string password_, std::string username_) :
-        id(id_), login(std::move(login_)), password(std::move(password_)), username(std::move(username_)) {
-}
-User::User(std::string login_, std::string password_, std::string username_) :
-        id(0), login(std::move(login_)), password(std::move(password_)), username(std::move(username_)) {
-}
-
-const std::string &User::getLogin() const {
-    return login;
-}
-
-void User::setLogin(const std::string &login_) {
-    User::login = login_;
-}
-
-const std::string &User::getPassword() const {
-    return password;
-}
-
-void User::setPassword(const std::string &password_) {
-    User::password = password_;
-}
-
-const std::string &User::getUsername() const {
-    return username;
-}
-
-void User::setUsername(const std::string &username_) {
-    User::username = username_;
-}
-
-size_t User::getId() const {
-    return id;
-}
-
-std::ostream &operator<<(std::ostream &os, const User &user) {
-    os << "id: " << user.id << " login: " << user.login << " password: " << user.password << " username: "
-       << user.username;
-    return os;
-}
\ No newline at end of file
diff --git a/client/internal/httpClient/include/HttpClientManager.h b/client/internal/httpClient/include/HttpClientManager.h
index 7c3ed331ffc822240414d9151f253b549b74e90d..eb93fcb01ee452bd0db18918760ab8f4fd7cbc51 100644
--- a/client/internal/httpClient/include/HttpClientManager.h
+++ b/client/internal/httpClient/include/HttpClientManager.h
@@ -14,17 +14,17 @@
 
 class HttpClientManager {
 public:
-    HttpClientManager(std::string_view host_, std::string_view port_, std::string_view saved_path_);
+    HttpClientManager(std::string_view host_, std::string_view port_);
 
-    unsigned int loginUser(const std::string &login, const std::string &password);
-    unsigned int registerUser(const std::string &login, const std::string &username, const std::string &password);
+    std::pair<unsigned, User> loginUser(const std::string &login, const std::string &password);
+    std::pair<unsigned, User> registerUser(const std::string &login, const std::string &username,
+                                           const std::string &password);
     unsigned int submitSolution(const int& user_id, const std::string &path_to_solution);
     unsigned int getAllSolutionsForTask(const int& user_id, const int& task_id);
     std::vector<Task> getAllTasks();
     std::vector<Metric> getMetrics(const int& sol_id);
     void setHttpClient(std::shared_ptr<IHttpClient> client_);
 private:
-    std::string saved_path;
     std::string host;
     std::string port;
     std::shared_ptr<IHttpClient> client;
diff --git a/client/internal/httpClient/include/Serializer.h b/client/internal/httpClient/include/Serializer.h
index 4f4dc3206297456d77c351cae15fff724fac655c..42be6c840fb20f92e06a50248c737a9fef90f3c6 100644
--- a/client/internal/httpClient/include/Serializer.h
+++ b/client/internal/httpClient/include/Serializer.h
@@ -1,12 +1,14 @@
-#ifndef APP_HTTPCLIENT_HTTPCLIENT_SERIALIZER_H_
-#define APP_HTTPCLIENT_HTTPCLIENT_SERIALIZER_H_
+#pragma once
 
 #include <vector>
 #include <memory>
 #include <string>
+#include "User.h"
 
-class Serializer {};
+class Serializer {
+public:
+    std::string serialLoginData(std::string_view login, std::string_view password);
+    std::string serialRegisterData(std::string_view login, std::string_view username, std::string_view password);
+    User deserialUserData(std::string_view body);
+};
 
-
-
-#endif  // APP_HTTPCLIENT_HTTPCLIENT_SERIALIZER_H_
diff --git a/client/internal/httpClient/src/HttpClientManager.cpp b/client/internal/httpClient/src/HttpClientManager.cpp
index 9d7b1e4243d37ab0ad408f9d48613ab0edcbf7ec..a269f65a6a2ce3c831859d8c4c7d0fbc80980348 100644
--- a/client/internal/httpClient/src/HttpClientManager.cpp
+++ b/client/internal/httpClient/src/HttpClientManager.cpp
@@ -6,18 +6,36 @@
 
 #include "HttpClient.h"
 
-HttpClientManager::HttpClientManager(std::string_view host_, std::string_view port_, std::string_view saved_path_) :
-        host(host_), port(port_), saved_path(saved_path_),
+HttpClientManager::HttpClientManager(std::string_view host_, std::string_view port_) :
+        host(host_), port(port_),
         client(std::make_shared<HttpClient>(host_, port_)),
         serializer(std::make_shared<Serializer>()) {}
 
-unsigned int HttpClientManager::loginUser(const std::string &login, const std::string &password) {
-
+std::pair<unsigned, User> HttpClientManager::loginUser(const std::string &login, const std::string &password) {
+    std::string body = serializer->serialLoginData(login, password);
+    http::response<http::dynamic_body> res = client->makeGetRequest("/user/login", body);
+    unsigned status = res.result_int();
+    std::string res_body;
+    for (auto seq : res.body().data()) {
+        auto* cbuf = boost::asio::buffer_cast<const char*>(seq);
+        res_body.append(cbuf, boost::asio::buffer_size(seq));
+    }
+    User user = serializer->deserialUserData(res_body);
+    return {status, user};
 }
 
-unsigned int HttpClientManager::registerUser(const std::string &login, const std::string &username,
+std::pair<unsigned, User> HttpClientManager::registerUser(const std::string &login, const std::string &username,
                                              const std::string &password) {
-    return 0;
+    std::string body = serializer->serialRegisterData(login, username, password);
+    http::response<http::dynamic_body> res = client->makeGetRequest("/user/register", body);
+    unsigned status = res.result_int();
+    std::string res_body;
+    for (auto seq : res.body().data()) {
+        auto* cbuf = boost::asio::buffer_cast<const char*>(seq);
+        res_body.append(cbuf, boost::asio::buffer_size(seq));
+    }
+    User user = serializer->deserialUserData(res_body);
+    return {status, user};
 }
 
 unsigned int HttpClientManager::submitSolution(const int &user_id, const std::string &path_to_sound) {
diff --git a/client/internal/httpClient/src/Serializer.cpp b/client/internal/httpClient/src/Serializer.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c2d556799fb6933f1b49735e6905b70700c9d641
--- /dev/null
+++ b/client/internal/httpClient/src/Serializer.cpp
@@ -0,0 +1,39 @@
+#include "Serializer.h"
+
+#include <sstream>
+#include <boost/property_tree/ptree.hpp>
+#include <boost/property_tree/json_parser.hpp>
+
+std::string Serializer::serialLoginData(std::string_view login, std::string_view password) {
+    boost::property_tree::ptree json;
+    json.put("login", login);
+    json.put("password", password);
+    std::stringstream out;
+    boost::property_tree::write_json(out, json);
+    return out.str();
+}
+
+User Serializer::deserialUserData(std::string_view body) {
+    std::stringstream ss;
+    ss << body;
+    boost::property_tree::ptree json;
+    boost::property_tree::read_json(ss, json);
+    User res = {
+            json.get<std::size_t>("user_id"),
+            json.get<std::string>("login"),
+            json.get<std::string>("password"),
+            json.get<std::string>("username")
+    };
+    return res;
+}
+
+std::string
+Serializer::serialRegisterData(std::string_view login, std::string_view username, std::string_view password) {
+    boost::property_tree::ptree json;
+    json.put("login", login);
+    json.put("username", username);
+    json.put("password", password);
+    std::stringstream out;
+    boost::property_tree::write_json(out, json);
+    return out.str();
+}