date-fns date-fns (a.k.a Date Functions) is a library which gives you functions to deal with dates. It is great package with a small size. dotenv dotenv create a .env file to store your environment variables. So when you publish that project online you use the environment variables which you deploy the project on. socket.io Help you use the sockets to create realtime communications such as chat apps. UUID Help you create a universal unique identifier (UUID) with one line of code.