diff --git a/app/models/sound.py b/app/models/sound.py
index 9d75142..2554361 100644
--- a/app/models/sound.py
+++ b/app/models/sound.py
@@ -3,11 +3,13 @@
 from datetime import datetime
 from enum import Enum
 from typing import Optional
+from zoneinfo import ZoneInfo
 
-from app.database import db
 from sqlalchemy import Boolean, DateTime, Integer, String
 from sqlalchemy.orm import Mapped, mapped_column
 
+from app.database import db
+
 
 class SoundType(Enum):
     """Sound type enumeration."""
@@ -75,13 +77,13 @@ class Sound(db.Model):
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
     updated_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
-        onupdate=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
+        onupdate=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
 
@@ -114,7 +116,7 @@ class Sound(db.Model):
     def increment_play_count(self) -> None:
         """Increment the play count for this sound."""
         self.play_count += 1
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         db.session.commit()
 
     def set_normalized_info(
@@ -130,7 +132,7 @@ class Sound(db.Model):
         self.normalized_size = normalized_size
         self.normalized_hash = normalized_hash
         self.is_normalized = True
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def clear_normalized_info(self) -> None:
         """Clear normalized sound information."""
@@ -139,7 +141,7 @@ class Sound(db.Model):
         self.normalized_hash = None
         self.normalized_size = None
         self.is_normalized = False
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def update_file_info(
         self,
@@ -153,7 +155,7 @@ class Sound(db.Model):
         self.duration = duration
         self.size = size
         self.hash = hash_value
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     @classmethod
     def find_by_hash(cls, hash_value: str) -> Optional["Sound"]:
diff --git a/app/models/sound_played.py b/app/models/sound_played.py
index 6854790..19cd27e 100644
--- a/app/models/sound_played.py
+++ b/app/models/sound_played.py
@@ -1,11 +1,13 @@
 """Sound played tracking model."""
 
 from datetime import datetime
+from zoneinfo import ZoneInfo
 
-from app.database import db
 from sqlalchemy import DateTime, ForeignKey, Integer, func, text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
+from app.database import db
+
 
 class SoundPlayed(db.Model):
     """Model to track when users play sounds."""
@@ -16,15 +18,21 @@ class SoundPlayed(db.Model):
 
     # Foreign keys
     user_id: Mapped[int] = mapped_column(
-        Integer, ForeignKey("users.id"), nullable=False,
+        Integer,
+        ForeignKey("users.id"),
+        nullable=False,
     )
     sound_id: Mapped[int] = mapped_column(
-        Integer, ForeignKey("sounds.id"), nullable=False,
+        Integer,
+        ForeignKey("sounds.id"),
+        nullable=False,
     )
 
     # Timestamp
     played_at: Mapped[datetime] = mapped_column(
-        DateTime, default=datetime.utcnow, nullable=False,
+        DateTime,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
+        nullable=False,
     )
 
     # Relationships
@@ -45,17 +53,25 @@ class SoundPlayed(db.Model):
             "user_id": self.user_id,
             "sound_id": self.sound_id,
             "played_at": self.played_at.isoformat(),
-            "user": {
-                "id": self.user.id,
-                "name": self.user.name,
-                "email": self.user.email,
-            } if self.user else None,
-            "sound": {
-                "id": self.sound.id,
-                "name": self.sound.name,
-                "filename": self.sound.filename,
-                "type": self.sound.type,
-            } if self.sound else None,
+            "user": (
+                {
+                    "id": self.user.id,
+                    "name": self.user.name,
+                    "email": self.user.email,
+                }
+                if self.user
+                else None
+            ),
+            "sound": (
+                {
+                    "id": self.sound.id,
+                    "name": self.sound.name,
+                    "filename": self.sound.filename,
+                    "type": self.sound.type,
+                }
+                if self.sound
+                else None
+            ),
         }
 
     @classmethod
@@ -79,7 +95,10 @@ class SoundPlayed(db.Model):
 
     @classmethod
     def get_user_plays(
-        cls, user_id: int, limit: int = 50, offset: int = 0,
+        cls,
+        user_id: int,
+        limit: int = 50,
+        offset: int = 0,
     ) -> list["SoundPlayed"]:
         """Get recent plays for a specific user."""
         return (
@@ -92,7 +111,10 @@ class SoundPlayed(db.Model):
 
     @classmethod
     def get_sound_plays(
-        cls, sound_id: int, limit: int = 50, offset: int = 0,
+        cls,
+        sound_id: int,
+        limit: int = 50,
+        offset: int = 0,
     ) -> list["SoundPlayed"]:
         """Get recent plays for a specific sound."""
         return (
@@ -105,7 +127,9 @@ class SoundPlayed(db.Model):
 
     @classmethod
     def get_recent_plays(
-        cls, limit: int = 100, offset: int = 0,
+        cls,
+        limit: int = 100,
+        offset: int = 0,
     ) -> list["SoundPlayed"]:
         """Get recent plays across all users and sounds."""
         return (
@@ -127,7 +151,9 @@ class SoundPlayed(db.Model):
 
     @classmethod
     def get_popular_sounds(
-        cls, limit: int = 10, days: int | None = None,
+        cls,
+        limit: int = 10,
+        days: int | None = None,
     ) -> list[dict]:
         """Get most popular sounds with play counts."""
         from app.models.sound import Sound
@@ -144,7 +170,7 @@ class SoundPlayed(db.Model):
 
         if days:
             query = query.filter(
-                cls.played_at >= text(f"datetime('now', '-{days} days')")
+                cls.played_at >= text(f"datetime('now', '-{days} days')"),
             )
 
         results = query.limit(limit).all()
@@ -154,15 +180,17 @@ class SoundPlayed(db.Model):
         for result in results:
             sound = Sound.query.get(result.sound_id)
             if sound:
-                popular_sounds.append({
-                    "sound": sound.to_dict(),
-                    "play_count": result.play_count,
-                    "last_played": (
-                        result.last_played.isoformat()
-                        if result.last_played
-                        else None
-                    ),
-                })
+                popular_sounds.append(
+                    {
+                        "sound": sound.to_dict(),
+                        "play_count": result.play_count,
+                        "last_played": (
+                            result.last_played.isoformat()
+                            if result.last_played
+                            else None
+                        ),
+                    }
+                )
 
         return popular_sounds
 
@@ -193,7 +221,8 @@ class SoundPlayed(db.Model):
         # Get favorite sound
         favorite_query = (
             db.session.query(
-                cls.sound_id, func.count(cls.id).label("play_count")
+                cls.sound_id,
+                func.count(cls.id).label("play_count"),
             )
             .filter_by(user_id=user_id)
             .group_by(cls.sound_id)
@@ -232,4 +261,4 @@ class SoundPlayed(db.Model):
             "last_play": (
                 last_play.played_at.isoformat() if last_play else None
             ),
-        }
\ No newline at end of file
+        }
diff --git a/app/models/user.py b/app/models/user.py
index 53a3d74..898cc9c 100644
--- a/app/models/user.py
+++ b/app/models/user.py
@@ -3,6 +3,7 @@
 import secrets
 from datetime import datetime
 from typing import TYPE_CHECKING, Optional
+from zoneinfo import ZoneInfo
 
 from sqlalchemy import DateTime, ForeignKey, Integer, String
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -63,13 +64,13 @@ class User(db.Model):
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
     updated_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
-        onupdate=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
+        onupdate=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
 
@@ -103,9 +104,11 @@ class User(db.Model):
             "role": self.role,
             "is_active": self.is_active,
             "api_token": self.api_token,
-            "api_token_expires_at": self.api_token_expires_at.isoformat()
-            if self.api_token_expires_at
-            else None,
+            "api_token_expires_at": (
+                self.api_token_expires_at.isoformat()
+                if self.api_token_expires_at
+                else None
+            ),
             "providers": providers,
             "plan": self.plan.to_dict() if self.plan else None,
             "credits": self.credits,
@@ -129,13 +132,13 @@ class User(db.Model):
         self.email = provider_data.get("email", self.email)
         self.name = provider_data.get("name", self.name)
         self.picture = provider_data.get("picture", self.picture)
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         db.session.commit()
 
     def set_password(self, password: str) -> None:
         """Hash and set user password."""
         self.password_hash = generate_password_hash(password)
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def check_password(self, password: str) -> bool:
         """Check if provided password matches user's password."""
@@ -151,7 +154,7 @@ class User(db.Model):
         """Generate a new API token for the user."""
         self.api_token = secrets.token_urlsafe(32)
         self.api_token_expires_at = None  # No expiration by default
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         return self.api_token
 
     def is_api_token_valid(self) -> bool:
@@ -162,23 +165,23 @@ class User(db.Model):
         if self.api_token_expires_at is None:
             return True  # No expiration
 
-        return datetime.utcnow() < self.api_token_expires_at
+        return datetime.now(tz=ZoneInfo("UTC")) < self.api_token_expires_at
 
     def revoke_api_token(self) -> None:
         """Revoke the user's API token."""
         self.api_token = None
         self.api_token_expires_at = None
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def activate(self) -> None:
         """Activate the user account."""
         self.is_active = True
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     def deactivate(self) -> None:
         """Deactivate the user account."""
         self.is_active = False
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
     @classmethod
     def find_by_email(cls, email: str) -> Optional["User"]:
@@ -218,7 +221,7 @@ class User(db.Model):
             oauth_provider.email = email
             oauth_provider.name = name
             oauth_provider.picture = picture
-            oauth_provider.updated_at = datetime.utcnow()
+            oauth_provider.updated_at = datetime.now(tz=ZoneInfo("UTC"))
 
             # Update user info with latest data
             user.update_from_provider(
diff --git a/app/models/user_oauth.py b/app/models/user_oauth.py
index fedeb13..b987e72 100644
--- a/app/models/user_oauth.py
+++ b/app/models/user_oauth.py
@@ -2,6 +2,7 @@
 
 from datetime import datetime
 from typing import TYPE_CHECKING, Optional
+from zoneinfo import ZoneInfo
 
 from sqlalchemy import DateTime, ForeignKey, String, Text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -34,13 +35,13 @@ class UserOAuth(db.Model):
     # Timestamps
     created_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
     updated_at: Mapped[datetime] = mapped_column(
         DateTime,
-        default=datetime.utcnow,
-        onupdate=datetime.utcnow,
+        default=lambda: datetime.now(tz=ZoneInfo("UTC")),
+        onupdate=lambda: datetime.now(tz=ZoneInfo("UTC")),
         nullable=False,
     )
 
@@ -107,7 +108,7 @@ class UserOAuth(db.Model):
             oauth_provider.email = email
             oauth_provider.name = name
             oauth_provider.picture = picture
-            oauth_provider.updated_at = datetime.utcnow()
+            oauth_provider.updated_at = datetime.now(tz=ZoneInfo("UTC"))
         else:
             # Create new provider
             oauth_provider = cls(
diff --git a/app/services/credit_service.py b/app/services/credit_service.py
index d065cca..f9dacd6 100644
--- a/app/services/credit_service.py
+++ b/app/services/credit_service.py
@@ -2,6 +2,7 @@
 
 import logging
 from datetime import datetime
+from zoneinfo import ZoneInfo
 
 from app.database import db
 from app.models.user import User
@@ -62,7 +63,7 @@ class CreditService:
 
                 if credits_added > 0:
                     user.credits = new_credits
-                    user.updated_at = datetime.utcnow()
+                    user.updated_at = datetime.now(tz=ZoneInfo("UTC"))
                     total_credits_added += credits_added
 
                     logger.debug(