Hoteldruid is designed to manage weekly or daily rental of house apartments or hotel rooms. It uses a PostgreSQL, MySQL, or SQLite database as a backend. Reservations can be assigned to rooms automatically with user-defined rules. Pages with forms to check availability for Internet sites can be created. It supports multiple users with a privileges system. Documents and invoices can be printed, saved, and emailed.
Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.