There is no single xdn developer.
Instead, there is a number of xdn developer teams with excellent IT knowledge and deep understanding of CryptoNote technology and cryptocurrency phenomenon.
Each team is focused on its own project part, there are professional programmers, economists, managers and testers united by one idea, united by xdn, but separated in time and space.
https://cointelegraph.com/news/what-the-duck-cryptonote-inspired-ducknote-xdndNOte disappeared after the ICO, taking the money of many investors.