Duffel is building the new software backbone of the travel industry. Their first product is the Flights API, a developer-friendly platform that enables any business to instantly search flights, make bookings, reserve seats, and sell paid extras like checked bags.

How do we know they use phoenix:

https://elixir-lang.org/blog/2020/12/10/integrating-travel-with-elixir-at-duffel/ "They chose the Erlang VM, alongside the Phoenix web framework and the Ecto database library as their stack to launch their initial JSON API."

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