Syncthing: Let Your Desktop Be Local Server For Your Mobile Device

Syncthing is an open-source, free file synchronization application, written in GO programming language, available for almost every operating system Linux, Unix, Windows, Mac, BSD, Android and iOS. It can sync between device that are present on the local network (no Internet required), or between remote devices over the Internet. It is secure and safe since both things are built-in into the application.
Syncthing replaces proprietary sync and cloud services with something open, trustworthy and decentralized. Your data is your data alone and you deserve to choose where it is stored, if it is shared with some third party and how it’s transmitted over the Internet. It should be safe from data loss, protecting the user’s data is priority. Developers took reasonable precaution to avoid corrupting the user’s files.