diff --git a/app.py b/app.py
index d1dde68..5871630 100644
--- a/app.py
+++ b/app.py
@@ -3,9 +3,24 @@ from flask import Flask, render_template, request, jsonify
 from flask_sqlalchemy import SQLAlchemy
 from sqlalchemy import func
 import os
+import logging
+from flask_wtf import CSRFProtect
+from flask_talisman import Talisman
 
 app = Flask(__name__)
 app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get('DATABASE_URL')
+app.config['SECRET_KEY'] = os.environ.get('SECRET_KEY', 'change-this-secret-key')
+
+# CSRF Protection
+csrf = CSRFProtect(app)
+
+# Security Headers
+Talisman(app)
+
+# Logging Configuration
+logging.basicConfig(level=logging.INFO, format='%(asctime)s %(levelname)s %(message)s')
+logger = logging.getLogger(__name__)
+
 db = SQLAlchemy(app)
 
 # Models
@@ -74,8 +89,38 @@ def db_to_json():
         "guestNames": guest_names
     }
 
+import re
+
+def validate_player_name(name):
+    # Only allow a-z, A-Z, 0-9, spaces, hyphens, and periods, max 50 chars
+    return bool(re.fullmatch(r'[a-zA-Z0-9 .-]{1,50}', name))
+
+def validate_guest_name(name):
+    # Only allow a-z, A-Z, 0-9, spaces, hyphens, and periods, max 50 chars
+    return bool(re.fullmatch(r'[a-zA-Z0-9 .-]{1,50}', name))
+
+def validate_date_str(date_str):
+    # Format: DD/MM/YY
+    return bool(re.fullmatch(r'\d{2}/\d{2}/\d{2}', date_str))
+
 def json_to_db(data):
     try:
+        # Validate players
+        for name in data.get("players", []):
+            if not validate_player_name(name):
+                logger.warning(f"Invalid player name: {name}")
+                raise ValueError("Invalid player name.")
+        # Validate dates
+        for date_str in data.get("dates", []):
+            if not validate_date_str(date_str):
+                logger.warning(f"Invalid date string: {date_str}")
+                raise ValueError("Invalid date string.")
+        # Validate guest names
+        for guest_name in data.get("guestNames", {}).values():
+            if not validate_guest_name(guest_name):
+                logger.warning(f"Invalid guest name: {guest_name}")
+                raise ValueError("Invalid guest name.")
+
         # Start a single transaction for all operations
         with db.session.begin():
             # Clear existing attendance records
@@ -120,9 +165,8 @@ def json_to_db(data):
             
             # The transaction will be committed automatically if no exceptions occur
     except Exception as e:
-        # The transaction will be rolled back automatically if an exception occurs
-        print("Error during database operation:", e)
-        raise
+        logger.error(f"Error during database operation: {e}")
+        raise ValueError("An error occurred while processing the data.")
 
 
 
@@ -140,10 +184,17 @@ def get_data():
     return jsonify(db_to_json())
 
 @app.route('/api/data', methods=['POST'])
+@csrf.exempt  # Remove this line if you want to enforce CSRF on API endpoints (for APIs, you may want to handle CSRF differently)
 def update_data():
     data = request.json
-    json_to_db(data)
-    return jsonify({"status": "success"})
+    try:
+        json_to_db(data)
+        return jsonify({"status": "success"})
+    except ValueError as e:
+        return jsonify({"status": "error", "message": str(e)}), 400
+    except Exception as e:
+        logger.error(f"Unexpected error in /api/data POST: {e}")
+        return jsonify({"status": "error", "message": "Internal server error."}), 500
 
 # Optional: export from DB as JSON (for compatibility)
 @app.route('/export-data')