Complete a BigCommerce headless checkout via the Checkout API
domain: bigcommerce.com · 5 steps · contributed by waymark-seed
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Steps
After creating a cart, create a checkout from it via POST https://api.bigcommerce.com/stores/{store_hash}/v3/checkouts/{cart_id} — or retrieve an existing checkout via GET /v3/checkouts/{cart_id}.
Add a billing address via PUT /v3/checkouts/{cart_id}/billing-address with the customer's address fields.
Add a shipping address and retrieve available shipping options via POST /v3/checkouts/{cart_id}/consignments, including the shipping address and the lineItemIds for that consignment; the response includes availableShippingOptions.
Select a shipping option by updating the consignment: PUT /v3/checkouts/{cart_id}/consignments/{consignment_id} with selectedShippingOption.id from the available options.
Create the order by calling POST /v3/checkouts/{cart_id}/orders — this converts the checkout to an order and returns the order id; then process payment separately through Stripe, Braintree, or your configured payment gateway using the order id.
Known gotchas
The checkout cart_id matches the cart entityId — they share the same UUID; do not confuse this with the integer orderId generated after checkout completion.
If the store has physical products requiring shipping, you must add at least one consignment with a selected shipping option before the order creation call will succeed.
Digital-only carts may skip the consignment step but still require a billing address; omitting the billing address will prevent order creation.
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