This post explains how to create a md5 signature for the flight search API.                             

Sort the request parameters alphabetically:

host=beta.aviasales.com&locale=en&marker=PutYourMarkerHere&adults=1&children=0&infants=0&date=2022-05-25&destination=BCN&origin=LON&date=2022-06-18&destination=LON&origin=BCN&trip_class=Y&user_ip=127.0.0.1. 

If the element contains an array (e.g., segments) or a list of parameters (e.g., passengers), the content of this element is sorted separately.

This content is not sorted with parameters of the upper level. 

Assemble a string containing only the values ​​of the parameters (ranking is the same as in step 1): beta.aviasales.com:en:PutYourMarkerHere:1:0:0:2022-05-25:BCN:LON:2022-06-18:LON:BCN:Y:127.0.0.1. The values ​​are separated by a colon.

Add to the beginning of this string value of your affiliate API token:

PutYourTokenHere:beta.aviasales.com:en:PutYourMarkerHere:1:0:0:2022-05-25:BCN:LON:2022-06-18:LON:BCN:Y:127.0.0.1

Use the resulting string to calculate the md-5 signature. The result is the signature of our request.
Attention! Signature is case-sensitive.