To use the TocToc mobile application, you must first generate your first QR Code, by providing it with a name, a catchphrase, and a welcome message on the web interface.   Once created, you can print it and display it on the door of your home or business. Your visitors will be able to scan the code and leave you a message, even in your absence.   You can easily consult these messages in the list of messages of the TocToc application.