diff --git a/app/__init__.py b/app/__init__.py
index bbd9534..f9a5a00 100644
--- a/app/__init__.py
+++ b/app/__init__.py
@@ -5,13 +5,13 @@
 db = SQLAlchemy()
 
 
-def create_app():
+def create_app() -> Flask:
     app = Flask(__name__)
     app.config.from_object(Config)
     db.init_app(app)
 
     @app.route("/")
-    def home():
+    def home() -> str:
         return render_template("index.html")
 
     with app.app_context():
diff --git a/app/config.py b/app/config.py
index 06d2ed7..48dad6d 100644
--- a/app/config.py
+++ b/app/config.py
@@ -1,4 +1,5 @@
 import os
+from typing import Optional
 from dotenv import load_dotenv
 
 load_dotenv()
@@ -12,5 +13,6 @@ class Config:
         SQLALCHEMY_DATABASE_URI (str): URL untuk koneksi pada database yang diambil dari variabel "DATABASE_URL" yang ada di .env.
         SQLALCHEMY_TRACK_MODIFICATIONS (bool): Menonaktifkan pelacakan pada perubahan object untuk mencegah terjadinya overhead.
     """
-    SQLALCHEMY_DATABASE_URI = os.getenv("DATABASE_URL")
-    SQLALCHEMY_TRACK_MODIFICATIONS = False
+
+    SQLALCHEMY_DATABASE_URI: str | None = os.getenv("DATABASE_URL")
+    SQLALCHEMY_TRACK_MODIFICATIONS: bool = False
diff --git a/app/models.py b/app/models.py
index 63bc0cb..a219873 100644
--- a/app/models.py
+++ b/app/models.py
@@ -10,8 +10,8 @@ class Provinces(db.Model):
         name (str): Nama Provinsi yang tidak boleh kosong.
     """
 
-    code = db.Column(db.String(2), primary_key=True)
-    name = db.Column(db.String(255), nullable=False)
+    code: str = db.Column(db.String(2), primary_key=True)
+    name: str = db.Column(db.String(255), nullable=False)
 
 
 class Regencies(db.Model):
@@ -24,11 +24,11 @@ class Regencies(db.Model):
         name (str): Nama Kabupaten/Kota yang tidak boleh kosong.
     """
 
-    code = db.Column(db.String(5), primary_key=True)
-    province_code = db.Column(
+    code: str = db.Column(db.String(5), primary_key=True)
+    province_code: str = db.Column(
         db.String(2), db.ForeignKey("provinces.code"), nullable=False
     )
-    name = db.Column(db.String(255), nullable=False)
+    name: str = db.Column(db.String(255), nullable=False)
     province = db.relationship("Provinces", backref=db.backref("regencies", lazy=True))
 
 
@@ -42,11 +42,11 @@ class Districts(db.Model):
         name (str): Nama Kecamatan yang tidak boleh kosong.
     """
 
-    code = db.Column(db.String(8), primary_key=True)
-    regency_code = db.Column(
+    code: str = db.Column(db.String(8), primary_key=True)
+    regency_code: str = db.Column(
         db.String(5), db.ForeignKey("regencies.code"), nullable=False
     )
-    name = db.Column(db.String(255), nullable=False)
+    name: str = db.Column(db.String(255), nullable=False)
     regency = db.relationship("Regencies", backref=db.backref("districts", lazy=True))
 
 
@@ -60,9 +60,9 @@ class Villages(db.Model):
         name (str): Nama Desa yang tidak boleh kosong.
     """
 
-    code = db.Column(db.String(13), primary_key=True)
-    district_code = db.Column(
+    code: str = db.Column(db.String(13), primary_key=True)
+    district_code: str = db.Column(
         db.String(8), db.ForeignKey("districts.code"), nullable=False
     )
-    name = db.Column(db.String(255), nullable=False)
+    name: str = db.Column(db.String(255), nullable=False)
     district = db.relationship("Districts", backref=db.backref("villages", lazy=True))