Gordian Software builds APIs for travel websites to sell airline add-ons such as seat selection and baggage. It serves more than 10 million passengers per month and grew 1,400% in the first half of 2021. Launched in 2017, Gordian's customers include two of the three largest travel websites in the world. It is backed by Y Combinator and other leading investors. For more information, visit www.gordiansoftware.com.