Open Source Software
GNU Chess
7 open source Android apps for chess players
By Joshua Allen Holm (Alumni)June 22, 2016
https://opensource.com/life/16/6/open-source-android-apps-chess
A curated list of free and open-source chess resources
(information: October 2022)
https://www.reddit.com/r/sharechess/comments/v5pcje/a_curated_list_of_free_and_opensource_chess/