checkout.started

Once per checkout, when its form is bound and the cart has lines, or when the cart first gets lines after that; the steps of a multi-step checkout, a reload and a return from a payment gateway keep the same checkout.

CODE

next.on('checkout.started', (data, event) => {});

Data

Present: always; optional when it may be missing; campaign once the campaign is loaded; priced once the server priced the cart.

Field	Type	Present
`id`	`string`	always	One checkout in this tab, the same across its steps, reloads and a return from a payment gateway; a new one after an order is paid. Empty until `checkout.started`.
`step`	`number`	optional	The step of a multi-step checkout (`data-next-checkout-step`), from 1; none on a one-page checkout.
`cart`	`Cart`	always	The same cart `cart.*` events carry.
`user`	`User`	optional	The shopper, from `user.created` on.
`shipping_address`	`Address`	optional	From `address.entered` for the shipping address on.
`billing_same_as_shipping`	`boolean`	optional	On a checkout page: `false` once the shopper asks for a separate billing address.
`billing_address`	`Address`	optional	When `billing_same_as_shipping` is `false`, from `address.entered` for it on.
`payment_method`	`string`	optional	The API's code for the chosen payment method, on a checkout page: `card_token`, `paypal`, `apple_pay`, …

Cart

The cart every cart.* event carries. Prices are numbers in currency, there once the server priced these lines: total = subtotal − total_discount + shipping_method.price.

Field	Type	Present
`lines`	`CartItem[]`	always	Every line in the cart, the same package's lines merged.
`coupons`	`string[]`	always	The codes the shopper applied, uppercase. A bundle card's own codes are not listed.
`currency`	`string`	campaign	ISO 4217, such as `USD`.
`shipping_method`	`ShippingMethod`	optional	The selected shipping method, and what shipping costs.
`subtotal`	`number`	priced	The products before discounts, without shipping.
`total_discount`	`number`	priced	The discounts on the products, without shipping's: the sum of `discounts`.
`total`	`number`	priced	What the shopper pays.
`discounts`	`Discount[]`	priced	The discounts on the products, one per offer.
`discount_percentage`	`number`	priced	`total_discount ÷ subtotal × 100`, to two decimals; `0` without a discount.
`quantity`	`number`	always	Units in the cart: each line's quantity.

User

The shopper, as the store's user on the Open Cart and the order.

Field	Type	Present
`email`	`string`	optional	As typed, trimmed; none when `data-trigger-on` created the user without one.
`first_name`	`string`	always
`last_name`	`string`	always
`phone`	`string`	optional	In E.164 once the address service read it, else the digits typed.
`accepts_marketing`	`boolean`	always	The marketing checkbox, as sent with the Open Cart and the order.
`language`	`string`	always	The language the store keeps for the shopper, such as `en`.
`ip`	`string`	optional	The shopper's IP address, as the store recorded it with the Open Cart, else as the address service saw it; none when neither knows it.
`user_agent`	`string`	always	As the store recorded it with the Open Cart, else the browser's.

Address

A postal address as the shopper entered it, once every field its country requires is valid.

Field	Type	Present
`first_name`	`string`	always
`last_name`	`string`	always
`line1`	`string`	always
`line2`	`string`	optional
`city`	`string`	optional	None in a country whose addresses have no city, such as Singapore.
`state`	`string`	optional	The state or province code, in a country that has them.
`postcode`	`string`	optional
`country`	`string`	always	ISO 3166-1 alpha-2.
`phone`	`string`	optional	In E.164 once the address service read it, else the digits typed.

CartItem

A line of the cart. Its prices are there once the server priced the cart.

Field	Type	Present
`package_id`	`number`	always	The package's `ref_id` in the campaign.
`quantity`	`number`	always	Package quantity.
`is_upsell`	`boolean`	optional	`true` for a line added after the order.
`properties`	`Record<string, string>`	optional	Line properties, such as a variant picked in a bundle slot.
`product_id`	`number`	campaign	The product in the store.
`product_title`	`string`	campaign	The product's name as customers see it, as on an order line; the package's name for a package without one.
`variant_id`	`number`	campaign	The product variant, for a product with variants.
`variant_title`	`string`	campaign	The variant's name, such as `Black / M`, for a product with variants.
`sku`	`string`	campaign	The product's Stock Keeping Unit.
`image`	`string`	campaign	The package's image URL.
`price`	`number`	priced	What one package costs after discounts.
`original_price`	`number`	priced	What one package costs before discounts; equal to `price` when nothing is taken off.
`total_discount`	`number`	priced	The discount on the line.
`total`	`number`	priced	`price × quantity`.
`subtotal`	`number`	priced	The line before discounts: `total = subtotal − total_discount`.
`discount_percentage`	`number`	priced	`total_discount ÷ subtotal × 100`, to two decimals; `0` without a discount.
`discounts`	`Discount[]`	priced	The discounts on the line.
`subscription`	`Subscription`	campaign	For a package billed again every interval.

ShippingMethod

The selected shipping method, and what shipping costs.

Field	Type	Present
`id`	`number`	always	The method's `ref_id`.
`code`	`string`	campaign	Such as `standard`.
`name`	`string`	priced	The method's name.
`price`	`number`	priced	What shipping costs after discounts; `0` is free shipping.
`original_price`	`number`	priced	What shipping costs before discounts.
`discounts`	`Discount[]`	priced	The discounts on shipping, such as a free-shipping offer.

Discount

A discount on the cart's products or on its shipping. Amounts are in the cart's currency.

Field	Type	Present
`name`	`string`	always	The offer's name.
`amount`	`number`	always	The amount taken off.
`source`	`"offer"` \| `"coupon"`	always	`coupon` for a code the shopper entered (it is in `coupons`); `offer` for an automatic offer or a bundle card's own code.
`code`	`string`	optional	The code, for a coupon.
`offer_id`	`number`	always	The offer that gave it.
`percentage`	`number`	optional	The percentage the offer is set to take off, as the API reports it, such as `20`. Its configured value, for a label such as “20% off”; the amount actually taken off is `amount`.

Subscription

A package billed again every interval.

Field	Type	Present
`interval`	`"day"` \| `"month"`	always	The unit of the renewal interval.
`interval_count`	`number`	always	How many `interval`s between renewals.
`price`	`number`	priced	What each renewal charges, after discounts.
`original_price`	`number`	priced	What each renewal charges before discounts.

Example

The second argument, with data inside. See Events for the envelope's fields.

CODE

{
  "event_id": "3f2b8c1d9e7a4b6c8d5e2f1a0b9c8d7e",
  "event_type": "checkout.started",
  "object": "checkout",
  "data": {
    "id": "4f1d2c8e9a7b6c5d4e3f2a1b0c9d8e7f",
    "cart": {
      "lines": [
        {
          "package_id": 1,
          "quantity": 1,
          "product_id": 400,
          "product_title": "Olympus Earbuds",
          "variant_id": 4001,
          "variant_title": "Black",
          "image": "https://cdn.test/1.png"
        }
      ],
      "coupons": [],
      "quantity": 1,
      "currency": "USD"
    },
    "billing_same_as_shipping": true,
    "payment_method": "card_token"
  },
  "created_at": "2026-11-04T08:30:00.000Z",
  "session_id": "0b8f3c2d1e4a4f6b9c7d5e3f2a1b0c9d",
  "sdk_version": "0.5.0"
}