diff --git a/app.py b/app.py
index 75b5cd2..9e92cd4 100644
--- a/app.py
+++ b/app.py
@@ -1,10 +1,15 @@
 import os
-from flask import Flask, request, json, abort
+from flask import Flask, request, json, abort, jsonify, make_response
 from flask_cors import CORS
 
 import sentry_sdk
 from sentry_sdk.integrations.flask import FlaskIntegration
 
+class InventoryError(Exception):
+    def __init__(self, message, item_id=None):
+        super().__init__(message)
+        self.item_id = item_id
+
 sentry_sdk.init(
     dsn="https://2ba68720d38e42079b243c9c5774e05c@sentry.io/1316515",
     integrations=[FlaskIntegration()],
@@ -37,13 +42,19 @@ def unhandled_exception():
 
 def process_order(cart):
     global Inventory
-    tempInventory = Inventory
+    tempInventory = Inventory.copy()
     for item in cart:
-        if Inventory[item['id']] <= 0:
-            raise Exception("Not enough inventory for " + item['id'])
+        item_id = item['id']
+        quantity = item.get('quantity', 1)
+        
+        if tempInventory[item_id] < quantity:
+            raise InventoryError(
+                f"Not enough inventory for '{item_id}'. Requested: {quantity}, Available: {tempInventory[item_id]}",
+                item_id
+            )
         else:
-            tempInventory[item['id']] -= 1
-            print 'Success: ' + item['id'] + ' was purchased, remaining stock is ' + str(tempInventory[item['id']])
+            tempInventory[item_id] -= quantity
+            print('Success: ' + item_id + ' was purchased, remaining stock is ' + str(tempInventory[item_id]))
     Inventory = tempInventory 
 
 @app.before_request
@@ -65,11 +76,16 @@ def sentry_event_context():
 
 @app.route('/checkout', methods=['POST'])
 def checkout():
+    try:
+        order = json.loads(request.data)
+        print("Processing order for: " + order["email"])
+        cart = order["cart"]
+        
+        process_order(cart)
 
-    order = json.loads(request.data)
-    print "Processing order for: " + order["email"]
-    cart = order["cart"]
-    
-    process_order(cart)
-
-    return 'Success'
+        return jsonify(message="Order processed successfully"), 200
+    except InventoryError as ie:
+        return make_response(jsonify(error=str(ie), itemId=ie.item_id), 400)
+    except Exception as e:
+        sentry_sdk.capture_exception(e)
+        return make_response(jsonify(error="An unexpected server error occurred..."), 500)