A free program for Android, by bparmentier.
WiFiKeyShare is an app that helps you easily share your Wi-Fi password by generating a QR code or by writing it to an NFC tag.
The QR code is recognized by most barcode scanner applications. The NFC tag is also recognized by most NFC devices.
This means that you can connect to the network just by scanning the tag.
The app has a built-in Wi-Fi configuration option. You can configure the app to connect to the network automatically when the QR code or tag is scanned.
You can also send the configuration via Android Beam. You need to be connected to the same Wi-Fi network on both devices to connect to it.
Note
The Wi-Fi passwords are saved on the device, so you will need to enter them manually for each network you want to share.