Checkout APIs

Cart Endpoints

# Create empty cart (guest)
POST /rest/V1/carts
Response: 145  (cart ID)

# Create cart for logged-in customer
POST /rest/V1/carts/mine
Response: 145

# Get cart by ID
GET /rest/V1/carts/{cartId}

# Get customer's active cart
GET /rest/V1/carts/mine

# Add item to cart
POST /rest/V1/carts/{cartId}/items
{
    "cartItem": {
        "sku": "simple-product",
        "qty": 2,
        "quote_id": 145
    }
}

# Update cart item
PUT /rest/V1/carts/{cartId}/items/{itemId}
{
    "cartItem": {
        "item_id": 5,
        "qty": 3,
        "quote_id": 145
    }
}

# Remove item from cart
DELETE /rest/V1/carts/{cartId}/items/{itemId}

# Delete cart
DELETE /rest/V1/carts/{cartId}

Guest Cart Operations

// Guest cart uses cart ID instead of auth token
// All endpoints work with /V1/guest-carts/{cartId} prefix

// Guest add item
POST /rest/V1/guest-carts/{cartId}/items
{
    "cartItem": {
        "sku": "simple-product",
        "qty": 1,
        "quote_id": "{guest-cart-id}"
    }
}

Set Shipping Address and Method

# Customer cart
POST /rest/V1/carts/mine/shipping-information
{
    "addressInformation": {
        "shipping_address": {
            "firstname": "John",
            "lastname": "Doe",
            "street": ["123 Main St"],
            "city": "New York",
            "region_id": 43,
            "postcode": "10001",
            "country_id": "US",
            "telephone": "555-1234",
            "email": "john@example.com"
        },
        "shipping_method_code": "flatrate",
        "shipping_carrier_code": "flatrate"
    }
}

# Guest cart
POST /rest/V1/guest-carts/{cartId}/shipping-information
// Same request body

Estimate Shipping Rates

# Get estimated shipping methods
POST /rest/V1/carts/mine/shipping-methods
{
    "address": {
        "country_id": "US",
        "postcode": "10001",
        "region_id": 43
    }
}

Response:
[
    {
        "carrier_code": "flatrate",
        "method_code": "flatrate",
        "carrier_title": "Flat Rate",
        "method_title": "Fixed",
        "price": 5.00
    },
    {
        "carrier_code": "tablerate",
        "method_code": "bestway",
        "carrier_title": "Table Rate",
        "method_title": "Best Way",
        "price": 7.50
    }
]

Set Payment and Place Order

# Set payment method and place order
POST /rest/V1/carts/mine/payment-information
{
    "paymentMethod": {
        "method": "checkmo"
    },
    "billingAddress": {
        "firstname": "John",
        "lastname": "Doe",
        "street": ["123 Main St"],
        "city": "New York",
        "region_id": 43,
        "postcode": "10001",
        "country_id": "US",
        "telephone": "555-1234",
        "email": "john@example.com"
    }
}

Response: 1  (order ID)

# Guest cart order placement
POST /rest/V1/guest-carts/{cartId}/payment-information
// Same request body

Payment Information Only

# Get available payment methods
GET /rest/V1/carts/mine/payment-methods

Response:
[
    {
        "code": "checkmo",
        "title": "Check / Money Order"
    },
    {
        "code": "banktransfer",
        "title": "Bank Transfer"
    }
]

# Set payment method without placing order
POST /rest/V1/carts/mine/set-payment-information
{
    "paymentMethod": {
        "method": "checkmo"
    },
    "billingAddress": {...}
}

Complete Checkout Flow (PHP)

namespace Vendor\Checkout\Service;

class CheckoutApi
{
    public function __construct(
        private \Magento\Quote\Api\CartRepositoryInterface $cartRepository,
        private \Magento\Quote\Api\GuestCartRepositoryInterface $guestCartRepository,
        private \Magento\Checkout\Api\Data\PaymentInformationInterfaceFactory $paymentInfoFactory,
        private \Magento\Checkout\Model\PaymentInformationManagement $paymentInfoManagement
    ) {}

    public function placeOrder(
        int $cartId,
        array $paymentData
    ): int {
        $cart = $this->cartRepository->get($cartId);

        // Set shipping
        $shippingAddress = $cart->getShippingAddress();
        $shippingAddress->setShippingMethod('flatrate_flatrate');
        $cart->save();

        // Set payment and place order
        $paymentInfo = $this->paymentInfoFactory->create();
        $paymentInfo->setPaymentMethod($paymentData['method']);
        $paymentInfo->setBillingAddress($this->createAddress($paymentData['billing']));

        $orderId = $this->paymentInfoManagement->savePaymentInformationAndPlaceOrder(
            $cartId,
            $paymentInfo
        );

        return $orderId;
    }
}