Author here, this is a refactoring of qr-filetransfer, already discussed in the past [0].
Here's how it works: qrcp binds a web server to the address of your Wi-Fi network interface on a random port and creates a handler for it. The default handler serves the content and exits the program when the transfer is complete. When used to receive files, qrcp serves an upload page and handles the transfer.
The tool prints a QR code that encodes the text:
http://{address}:{port}/{random_path}
To send one or more files (or directories):
qrcp /path/to/file
# Or
qrcp send /path/to/file
qrcp receive --output ~/Downloads