User management is a function that almost every application needs to use, but it is tedious to re-implement every application.
I have seen some SASS services that provide user authentication before, such as Firebase or parse. However, these platforms directly integrate services with their data services, which is not very common. In addition, a full stack framework such as Meteor also encapsulates logins as components, which is universal, but it is basically necessary to completely replace them with Meteor itself.
If you are a user yourself, to tell the truth, it is a great god that you can really write a complete set of user management by hand. In the commercial environment, you are not quite sure that you write it yourself. On the one hand, it is cost, and on the other hand, it is safety.
Therefore, I would like to ask you how to realize this function at present. Self-actualization? Ready-made libraries or solutions? Please explain the cost and safety.