FTPS (FTP over TLS) server for secure file sharing between devices over network.

Features:

User Permissions - Granular control over Read/Write operations
Per-User Root Folders - Isolated directories for each user
Path Security - Protection against directory traversal attacks
UTF-8 - Supports localized characters
Self-Signed Certificates - Auto-generate TLS certificates or bring your own

This is the Android app (Kotlin). No ads. Open source (CC0). Each user chooses a folder with the system picker. A notification keeps transfers running with the screen off.

Requires Android 6.0 or newer.

https://github.com/drweb86/dotnet-ftps-server