Warpinator for Android is a free and open source project that respects your privacy. As such, it collects no personal data. That being said, you may still want to know which information the application has access to and how it is handled.
To allow device discovery, we use the mDNS protocol. It works by sending the information that a Warpinator service is running on a certain IP address and port to everyone on the local network. It also discloses the phone's name to allow other users identify the device.
The devices then make an encrypted connection. All subsequent communication (transfers, transfer requests, profile picture and username, ...) goes through this channel. Only users with the same group code are able to connect. No personal files are accessed unless instructed by the user to be tranferred to a selected device.
The application can also log debug information if enabled in the settings. The log file is kept in a location that can be accessed by some other apps with sufficient permissions (eg. file managers, but also others). As the log may contain sensitive information (transferred file names, connected devices, ...), do not keep this option enabled unless needed for troubleshooting.