POST
/
v1
/
carts
/
:id
/
items
curl --location --request POST 'https://api.stateset.com/v1/carts/cart_0901f083-aa1c-43c5-af5c-0a9d2fc64e30/items' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer YOUR_API_KEY' \
--data-raw '{
    "product_id": "prod_789",
    "variant_id": "var_red_medium",
    "quantity": 1,
    "notes": "Gift wrap please"
}'

{
  "id": "cart_0901f083-aa1c-43c5-af5c-0a9d2fc64e30",
  "object": "cart",
  "customer_id": "cust_abc123",
  "status": "active",
  "items": [
    {
      "id": "ci_abc123",
      "product_id": "prod_123",
      "variant_id": "var_blue_large",
      "product_name": "Wireless Headphones",
      "variant_name": "Blue - Large",
      "quantity": 2,
      "unit_price": 9999,
      "subtotal": 19998
    },
    {
      "id": "ci_def456",
      "product_id": "prod_456",
      "product_name": "USB-C Cable",
      "quantity": 1,
      "unit_price": 1999,
      "subtotal": 1999
    },
    {
      "id": "ci_ghi789",
      "product_id": "prod_789",
      "variant_id": "var_red_medium",
      "product_name": "T-Shirt",
      "variant_name": "Red - Medium",
      "quantity": 1,
      "unit_price": 2499,
      "subtotal": 2499,
      "notes": "Gift wrap please",
      "inventory_status": "in_stock",
      "available_quantity": 15
    }
  ],
  "item_count": 4,
  "unique_item_count": 3,
  "subtotal": 24496,
  "tax_amount": 0,
  "shipping_amount": 0,
  "discount_amount": 2000,
  "total": 22496,
  "updated_at": "2024-06-20T15:00:00Z",
  "last_activity": "2024-06-20T15:00:00Z",
  "messages": [
    {
      "type": "info",
      "message": "Item added successfully"
    }
  ]
}
This endpoint adds one or more items to a cart. If the item already exists, it updates the quantity. Inventory availability is checked in real-time.

​
Authentication

This endpoint requires a valid API key with carts:write permissions. 
Authorization: Bearer YOUR_API_KEY

​
Path Parameters

​
id
string
required
The unique identifier of the cart

​
Request Body

​
product_id
string
required
Product ID to add
​
variant_id
string
Product variant ID (required if product has variants)
​
quantity
integer
required
Quantity to add (must be positive)
​
price_override
integer
Custom price in cents (requires special permissions)
​
notes
string
Special instructions for this item
​
metadata
object
Custom fields for the item
​
validate_inventory
boolean
default:"true"
Check inventory availability before adding
​
replace_quantity
boolean
default:"false"
Replace existing quantity instead of adding to it

​
Response

Returns the updated cart object. 
curl --location --request POST 'https://api.stateset.com/v1/carts/cart_0901f083-aa1c-43c5-af5c-0a9d2fc64e30/items' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer YOUR_API_KEY' \
--data-raw '{
    "product_id": "prod_789",
    "variant_id": "var_red_medium",
    "quantity": 1,
    "notes": "Gift wrap please"
}'

{
  "id": "cart_0901f083-aa1c-43c5-af5c-0a9d2fc64e30",
  "object": "cart",
  "customer_id": "cust_abc123",
  "status": "active",
  "items": [
    {
      "id": "ci_abc123",
      "product_id": "prod_123",
      "variant_id": "var_blue_large",
      "product_name": "Wireless Headphones",
      "variant_name": "Blue - Large",
      "quantity": 2,
      "unit_price": 9999,
      "subtotal": 19998
    },
    {
      "id": "ci_def456",
      "product_id": "prod_456",
      "product_name": "USB-C Cable",
      "quantity": 1,
      "unit_price": 1999,
      "subtotal": 1999
    },
    {
      "id": "ci_ghi789",
      "product_id": "prod_789",
      "variant_id": "var_red_medium",
      "product_name": "T-Shirt",
      "variant_name": "Red - Medium",
      "quantity": 1,
      "unit_price": 2499,
      "subtotal": 2499,
      "notes": "Gift wrap please",
      "inventory_status": "in_stock",
      "available_quantity": 15
    }
  ],
  "item_count": 4,
  "unique_item_count": 3,
  "subtotal": 24496,
  "tax_amount": 0,
  "shipping_amount": 0,
  "discount_amount": 2000,
  "total": 22496,
  "updated_at": "2024-06-20T15:00:00Z",
  "last_activity": "2024-06-20T15:00:00Z",
  "messages": [
    {
      "type": "info",
      "message": "Item added successfully"
    }
  ]
}