diff --git a/CHANGELOG.md b/CHANGELOG.md
index 925952b..7eb2fb0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.0.39] - 2023-05-02
+
+### Added
+
+- Prepare code for the UI improvements [@AivGitHub](https://github.com/AivGitHub/).
+
 ## [0.0.38] - 2023-04-11
 
 ### Added
diff --git a/api/serializers.py b/api/serializers.py
new file mode 100644
index 0000000..05a2293
--- /dev/null
+++ b/api/serializers.py
@@ -0,0 +1,75 @@
+from django.contrib.auth.models import update_last_login
+from django.db.utils import IntegrityError
+from rest_framework import serializers
+from rest_framework_simplejwt.serializers import TokenObtainPairSerializer
+from rest_framework_simplejwt.settings import api_settings
+
+from accounts.models import User
+from api.exceptions import UserAlreadyExists
+
+
+class UserSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = User
+        fields = [
+            'id', 'username', 'email',
+            'first_name', 'last_name', 'is_active',
+        ]
+        read_only_field = ['is_active']
+
+
+class SignInSerializer(TokenObtainPairSerializer):
+
+    def validate(self, attrs):
+        data = super().validate(attrs)
+        token = self.get_token(self.user)
+
+        data['user'] = UserSerializer(self.user).data
+        data['refresh'] = str(token)
+        data['access'] = str(token.access_token)
+
+        if api_settings.UPDATE_LAST_LOGIN:
+            update_last_login(None, self.user)
+
+        return data
+
+
+class SignUpSerializer(UserSerializer):
+    username = serializers.CharField(
+        max_length=64,
+        min_length=3,
+        write_only=True,
+        required=True
+    )
+    first_name = serializers.CharField(
+        max_length=150,
+        min_length=3
+    )
+    last_name = serializers.CharField(
+        max_length=50,
+        min_length=3
+    )
+    password = serializers.CharField(
+        max_length=128,
+        min_length=8,
+        write_only=True,
+        required=True
+    )
+    email = serializers.EmailField(
+        max_length=254,
+        write_only=True,
+        required=True
+    )
+
+    class Meta:
+        model = User
+        fields = [
+            'username', 'password', 'email',
+            'first_name', 'last_name', 'is_active',
+        ]
+
+    def create(self, validated_data):
+        try:
+            return User.objects.create_user(**validated_data)
+        except IntegrityError:
+            raise UserAlreadyExists()