Flight search API

The flight search API returns the cheapest itinerary per flight group for a route, dates, and passenger mix.

POST/Air/AirLowFareSearch

Access requires the permission air_low_fare_search

Send a POST request with one OriginDestinationInformations entry per leg. Use one entry for one-way, two for a round trip, and more for multi-city. The response is a set of priced itineraries, each with a FareSourceCode you carry into revalidate and book.

Want results as they arrive? Use the streaming endpoint AirLowFareSearchIncremental. It takes the same request and pushes itineraries over server-sent events.

Path parameters

None.

Query parameters

None.

Body parameters

Name Type Required Default Description

SessionId string Yes - Your session id.

AdultCount integer Yes - Adult passengers. Minimum 1.

ChildCount integer Yes - Child passengers. Minimum 0.

InfantCount integer Yes - Infant passengers, no seat. Minimum 0.

PricingSourceType string Yes - Pricing scope. Use All.

RequestOption string Yes - Result-set option. Use All.

NumberOfResults integer No 100 Basket size. 0 or omitted means 100. Any other value scales the same mix. Maximum 5000.

Provider string No - Optional inventory-source hint. Omit it to let the gateway aggregate every source and pick the best. An unknown value falls back to the configured default.

TravelPreference object, optional

Name	Type	Required	Default	Description
`CabinType`	integer	No	`1`	Cabin: `1` Economy, `2` Premium Economy, `3` Business, `4` Premium Business, `5` First, `6` Premium First.
`MaxStopsQuantity`	string	No	`All`	Cap on stops. Use `All` for any, or `0` for non-stop.
`AirTripType`	string	No	derived	`OneWay` or `Return`. Defaults from the number of legs.
`VendorPreferenceCodes`	array of string	No	-	Restrict results to these airline codes, for example `["TK","EK"]`.
`VendorExcludeCodes`	array of string	No	-	Exclude these airline codes.

OriginDestinationInformations array of object, required

One entry per leg. Minimum 1.

Name	Type	Required	Description
`OriginLocationCode`	string	Yes	Departure IATA code, for example `IST`.
`DestinationLocationCode`	string	Yes	Arrival IATA code, for example `DXB`.
`DepartureDateTime`	string	Yes	Local departure date and time, for example `2026-10-12T00:00:00`.
`OriginType`	string	No	Point qualifier, airport or city.
`DestinationType`	string	No	Point qualifier, airport or city.

Request

curl -X POST https://api.hermeseus.com/api/Air/AirLowFareSearch \
  -H "Content-Type: application/json" \
  -d '{
    "SessionId": "8f3c81d2-4a5b-4c6d-9e0f-1a2b3c4d5e6f",
    "AdultCount": 1,
    "ChildCount": 0,
    "InfantCount": 0,
    "PricingSourceType": "All",
    "RequestOption": "All",
    "TravelPreference": { "CabinType": 3, "AirTripType": "OneWay" },
    "OriginDestinationInformations": [
      {
        "OriginLocationCode": "IST",
        "DestinationLocationCode": "DXB",
        "DepartureDateTime": "2026-10-12T00:00:00"
      }
    ]
  }'

const res = await fetch("https://api.hermeseus.com/api/Air/AirLowFareSearch", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    SessionId: "8f3c81d2-4a5b-4c6d-9e0f-1a2b3c4d5e6f",
    AdultCount: 1,
    ChildCount: 0,
    InfantCount: 0,
    PricingSourceType: "All",
    RequestOption: "All",
    TravelPreference: { CabinType: 3, AirTripType: "OneWay" },
    OriginDestinationInformations: [
      {
        OriginLocationCode: "IST",
        DestinationLocationCode: "DXB",
        DepartureDateTime: "2026-10-12T00:00:00"
      }
    ]
  })
});

const data = await res.json();

import requests

res = requests.post(
    "https://api.hermeseus.com/api/Air/AirLowFareSearch",
    json={
        "SessionId": "8f3c81d2-4a5b-4c6d-9e0f-1a2b3c4d5e6f",
        "AdultCount": 1,
        "ChildCount": 0,
        "InfantCount": 0,
        "PricingSourceType": "All",
        "RequestOption": "All",
        "TravelPreference": {"CabinType": 3, "AirTripType": "OneWay"},
        "OriginDestinationInformations": [
            {
                "OriginLocationCode": "IST",
                "DestinationLocationCode": "DXB",
                "DepartureDateTime": "2026-10-12T00:00:00",
            }
        ],
    },
)

data = res.json()

Response

Returns the search id and the priced itineraries.

Field	Type	Description
`Success`	boolean	`true` on success.
`SearchId`	integer	Id of this search. Reuse it with `AirSearchData`.
`PricedItineraries`	array of object	The results. See below.
`Error`	object	`null` on success.

PricedItineraries[] object

Field	Type	Description
`FareSourceCode`	string	Opaque fare id. Carry it into revalidate and book.
`ValidatingAirlineCode`	string	Airline that validates the ticket, for example `TK`.
`DirectionInd`	integer	Journey direction indicator.
`IsPassportMandatory`	boolean	Whether passport details are required to book.
`AirItineraryPricingInfo`	object	Fare totals and the per-passenger breakdown.
`OriginDestinationOptions`	array of object	One entry per leg, each holding its flight segments.

AirItineraryPricingInfo object

Field	Type	Description
`FareType`	integer	Fare category code.
`ItinTotalFare`	object	`BaseFare`, `TotalTax`, `TotalFare` (numbers) and `Currency` (string). All amounts are USD.
`PtcFareBreakdown`	array of object	Fare per passenger type.

OriginDestinationOptions[].FlightSegments[] object

Field	Type	Description
`DepartureAirportLocationCode`	string	Departure IATA code.
`ArrivalAirportLocationCode`	string	Arrival IATA code.
`DepartureDateTime`	string	Local departure time.
`ArrivalDateTime`	string	Local arrival time.
`MarketingAirlineCode`	string	Marketing airline code.
`FlightNumber`	string	Flight number.
`ResBookDesigCode`	string	Booking class letter.
`Baggage`	string	Baggage allowance, for example `1PC`.
`CabinClassCode`	integer	Cabin of the segment, same enum as `CabinType`: `1` Economy through `6` Premium First.
`SeatsRemaining`	integer	Seats left at this fare.

{
  "Success": true,
  "SearchId": 428713,
  "PricedItineraries": [
    {
      "FareSourceCode": "dHA6ODc0NTE6ZmwxMjM0OjMyNw==",
      "ValidatingAirlineCode": "TK",
      "DirectionInd": 1,
      "IsPassportMandatory": true,
      "AirItineraryPricingInfo": {
        "FareType": 1,
        "ItinTotalFare": {
          "BaseFare": 182.40,
          "TotalTax": 37.20,
          "TotalFare": 219.60,
          "Currency": "USD"
        },
        "PtcFareBreakdown": [
          {
            "PassengerType": 1,
            "PassengerQuantity": 1,
            "BaseFare": 182.40,
            "TotalTax": 37.20,
            "TotalFare": 219.60,
            "Currency": "USD"
          }
        ]
      },
      "OriginDestinationOptions": [
        {
          "JourneyDurationPerMinute": 270,
          "FlightSegments": [
            {
              "DepartureAirportLocationCode": "IST",
              "ArrivalAirportLocationCode": "DXB",
              "DepartureDateTime": "2026-10-12T08:25:00",
              "ArrivalDateTime": "2026-10-12T14:55:00",
              "MarketingAirlineCode": "TK",
              "FlightNumber": "764",
              "ResBookDesigCode": "C",
              "Baggage": "2PC",
              "CabinClassCode": 3,
              "SeatsRemaining": 7
            }
          ]
        }
      ]
    }
  ],
  "Error": null
}

Errors

Code	Meaning	Fix
`Err0106001`	A required field is missing or invalid. The message names it.	Fix the field named in the message.
`Err0101001`	Missing or invalid session.	Create a new session and retry.
`Err0101006`	The office lacks the `air_low_fare_search` permission.	Ask to enable it.

See the full list on the errors reference.

Next step. Take the FareSourceCode of the itinerary the traveller picks and revalidate it before you book.