Ok, so first of all I seriously don´t know how what I want to do is actually called. So I put that title to try to explain it as better as possible.
The reason I want to make it like this is to avoid having the user to register/login etc.
This app is not planned for proffesional or production environment, I just want to it to learn and to share with friends, but i would like to have that funcionality, that you can share your “to-do” with your friends.
I have very little knowledge of backend/apis, but I´m not in a hurry, what should I know to approach this problem?