diff --git a/endpoints/cart.post.py b/endpoints/cart.post.py
index e69de29..7ef30d9 100644
--- a/endpoints/cart.post.py
+++ b/endpoints/cart.post.py
@@ -0,0 +1,36 @@
+from fastapi import APIRouter, HTTPException
+
+carts = []  # In-memory storage
+
+router = APIRouter()
+
+@router.post("/cart")
+async def add_to_cart(
+    user_id: str,
+    item_id: str,
+    quantity: int = 1
+):
+    """Add item to user's cart"""
+    cart = next((c for c in carts if c["user_id"] == user_id), None)
+    
+    if not cart:
+        cart = {
+            "user_id": user_id,
+            "items": []
+        }
+        carts.append(cart)
+
+    cart["items"].append({
+        "item_id": item_id,
+        "quantity": quantity
+    })
+
+    return {
+        "message": "Item added to cart",
+        "cart_id": user_id,
+        "items": cart["items"],
+        "features": {
+            "max_items": 10,
+            "expires_in": 3600
+        }
+    }
\ No newline at end of file