How to sync files between computers without a cloud?

Question

Data synchronization

There are 2 machines with 24\7 uptime and Internet connection, the task is to delete \ create \ make changes to a file on one of the machines, the changes should be accepted on the second.
The option with Yandex disks and so on disappears, the amount of traffic is 100-300 GB, you don’t want to pay for cloud storage when you don’t need it.
Both machines are behind NAT.
The presence of a client for android is desirable, but not critical.

Answer 1

syncthing

Answer 2

Any BitTorrent Sync options https://habr.com/post/266955/

Answer 3

BitTorrent Sync

Answer 4

BitTorrent? If he's alive of course

Answer 5

https://github.com/DmitryKoterov/dklab_realsync

Answer 6

https://www.resilio.com/individuals/
For personal use, the functionality of the free version is enough.
A large number of supported platforms. There are even versions for NAS! =)