Checkout Endpoint

Builds the cart, re-validates the priced flight and returns the totals the customer should review before confirming. Nothing is booked at this stage.

• Endpoint: /api/v1/unified-booking/checkout
• Method: POST

A flight can be sent alone or alongside other Onlynx products in the same products array — they will share one booking and one payment.

:::danger solution_id at checkout products[].solution_id must be the session_id returned by Pricing — not the solutionId from Search. Sending the search value fails with Flight pricing details not found or expired. Please search again. :::

Headers

Header	Value	Required	Description
Partner-Access-Token	Base64 String	Yes	Your encrypted AES-256 time-sensitive token.
X-Currency	Currency Code	Optional	Display currency. Defaults to your partner currency, then THB.
Accept-Language	Language Code	Optional	e.g. en, th, my.
Content-Type	application/json	Yes
Accept	application/json	Yes

Payload Parameters

Parameter	Type	Required	Description
products	Array	Yes	At least one product.
products[].product_type	String	Yes	pd9 for flights, all providers.
products[].solution_id	String	Yes	The pricing session_id.
products[].session_id	String	Optional	Provider session reference, when supplied by pricing.
products[].passengers	Array	Optional	If sent, each entry must carry a valid passenger_type.
products[].passengers[].passenger_type	String	Conditional	ADT, CHD or INF. Required when passengers is present.
products[].order_note	String	Optional	Free-text note stored on the booking item.
checkout_session_id	String	Optional	Returned in meta by a previous checkout call. Pass it back to reuse the same session instead of re-pricing.
payment_method	String	Optional	See the payment table below. Defaults to two_c2p for fee calculation.
payment_option	String	Optional	Must be valid for the chosen payment_method.
coupon_code	String	Optional	Campaign coupon to preview a discount.

:::note Passengers at checkout Full passenger details are only required at Checkout Confirm. At checkout you may send a minimal passengers array (just passenger_type per traveller) to preview add-on pricing, or omit it entirely. :::

Payment methods and options

payment_method	Valid payment_option values
two_c2p	card_payment, qr_payment, online_payment, two_c2p, and other configured options
gb_prime_pay	card_payment, qr_payment
ktc_pay	card_payment, alipay
tcc_pay	wechat_pay, alipay
ksher	qr_payment, online_payment
mm_qr	mm_qr
aya_mm_qr	aya_mm_qr
kbz_pay	kbz_pay_pgw
pay_later	pay_later
custom_guarantee	custom_guarantee

Bank fee

A 3% bank fee is added to the payable amount, except for these combinations, which are fee-free:

• pay_later
• two_c2p + qr_payment
• ksher + qr_payment
• mm_qr + mm_qr
• aya_mm_qr + aya_mm_qr
• kbz_pay + kbz_pay_pgw

Sample Payload

{
  "products": [
    {
      "product_type": "pd9",
      "solution_id": "HITIT_67f4c0a91e2b8d3a5c60f7b4",
      "order_note": "Window seat preferred",
      "passengers": [
        { "passenger_type": "ADT" }
      ]
    }
  ],
  "payment_method": "two_c2p",
  "payment_option": "card_payment"
}

With add-ons

To have baggage, meals and seats reflected in the checkout total, include them on the passengers exactly as you will at confirm:

{
  "products": [
    {
      "product_type": "pd9",
      "solution_id": "HITIT_67f4c0a91e2b8d3a5c60f7b4",
      "passengers": [
        {
          "passenger_type": "ADT",
          "ancillary": {
            "ancillary_id": "BAG_XBAG_20",
            "session_id": "HITIT_67f4c0b21e2b8d3a5c60f7c9"
          },
          "ancillaries": { "0-0": "BAG_XBAG_20" },
          "selected_seats": [
            {
              "seatNumber": "12A",
              "segmentId": "0-0",
              "session_id": "HITIT_67f4c0d31e2b8d3a5c60f8a2"
            }
          ]
        }
      ]
    }
  ],
  "payment_method": "two_c2p",
  "payment_option": "card_payment"
}

Response

:::warning Keys are snake_cased here All three /unified-booking/* endpoints pass their response through a snake-case converter. Fields that are camelCase on the flight endpoints arrive snake_cased here:

On /flights/*	On /unified-booking/*
solutionId	solution_id
journeyList	journey_list
segmentList	segment_list
pricingDetails	pricing_details
flightDetails	flight_details
segmentBaggageMappingList	segment_baggage_mapping_list
departureAirport	departure_airport

All-uppercase keys (ADT, CHD) and keys containing punctuation or spaces ("0-0", "Checked Baggage") are left untouched. :::

data is an array with one entry per product. A flight entry is the full pricing snapshot plus these cart fields:

Field	Type	Description
puid	String	Product unique ID within this cart.
product_type	String	pd9.
sub_total	Float	Flight total in display currency, including selected add-ons.
grand_total	Float	Same as sub_total for a flight line.
display_sub_total / display_grand_total	Float	Explicit display-currency totals.
display_currency	String	Display currency code.
session_id	String	The pricing session.
solution	Object	Full itinerary.
pricing_details	Object	Price breakdown, display and THB. See Pricing.
flight_details	Array	Pre-formatted journey summaries.

meta

Field	Type	Description
currency_code	String	Display currency.
sub_total	Float	Sum of all product totals.
grand_total	Float	sub_total minus discount, before bank fee.
discount_amount	Float	Coupon discount applied.
bank_fee_type	String|null	percentage when a fee applies, otherwise null.
bank_fee_amount	Float	Fee percentage, e.g. 3.
bank_fee_price	Float	Calculated fee.
bank_fee_sub_total	Float	Payable before fee.
bank_fee_grand_total	Float	Final amount payable, including bank fee.
payable	Float	Same as bank_fee_grand_total.
coupon_code	String|null	Echo of the submitted coupon.
payment_method / payment_option	String|null	Echo of the submitted payment selection.
checkout_session_id	String	Pass back on the next checkout call to reuse this session.
expires_at	String	ISO-8601 expiry of the checkout session.

Sample Response

Truncated.

{
  "result": 1,
  "message": "Checkout updated. Please review your details before continuing",
  "data": [
    {
      "puid": "0G7KY9KNb6",
      "product_type": "pd9",
      "session_id": "HITIT_67f4c0a91e2b8d3a5c60f7b4",
      "sub_total": 9830.00,
      "grand_total": 9830.00,
      "display_sub_total": 9830.00,
      "display_grand_total": 9830.00,
      "display_currency": "THB",
      "solution": { },
      "pricing_details": {
        "adults": {
          "count": 1,
          "fare": 7200.00,
          "tax": 1250.00,
          "total": 8450.00,
          "total_thb": 8450.00
        },
        "grand_total": 8450.00,
        "grand_total_thb": 8450.00,
        "currency_code": "THB"
      },
      "flight_details": [ ]
    }
  ],
  "meta": {
    "currency_code": "THB",
    "sub_total": 9830.00,
    "grand_total": 9830.00,
    "discount_amount": 0,
    "bank_fee_type": "percentage",
    "bank_fee_amount": 3,
    "bank_fee_price": 294.90,
    "bank_fee_sub_total": 9830.00,
    "bank_fee_grand_total": 10124.90,
    "payable": 10124.90,
    "coupon_code": null,
    "payment_method": "two_c2p",
    "payment_option": "card_payment",
    "checkout_session_id": "01JQ8R3V7K2M9XPD4T6Z0YHB5C",
    "expires_at": "2026-08-26T09:15:00+07:00"
  }
}

Errors

Message	Cause
Flight pricing details not found or expired. Please search again.	solution_id is not a valid pricing session, or the session expired.
Unsupported product type: {type}	product_type is not a recognised product.
HTTP 422 with errors	Validation failed — e.g. missing solution_id, invalid passenger_type.

Next Step

Call Checkout Confirm with full passenger and buyer details.