lichess.org's creator, Thibault Duplessis has an hn account [0] and has made some posts around here (although his last post appears to have been in 2015).

The entire thing is also free, open-source and with a very diverse tech stack behind it that includes Scala, Redis, MongoDB, Elasticsearch, Typescript, websockets, nginx and more [1]

[0] https://news.ycombinator.com/user?id=ornicar

[1] https://github.com/ornicar/lila