https://nextcloud.com/

https://github.com/nextcloud/
https://github.com/nextcloud/server

wahts new
http://www.opennet.ru/opennews/art.shtml?num=48028
https://nextcloud.com/blog/nextcloud-13-brings-secure-file-sync-and-collaboration-to-the-next-level/

presentations
2021
LearnLinuxTV - Nextcloud: Complete Setup Guide of 41:00
    https://www.youtube.com/watch?v=y4dtcr2NL5M