I have been reading a lot last few days about given topic. I am trying to find best solution. We are talking about internal Company app which we develop for ourself. Our users are part of the same Company but working in departments who handle operations, clients etc. This application is developed on .NET Framework 4.6.1 - MVC Web API (not .NET core). Problem that I am trying to resolve is finding existing app to buy or proposing development of the best solution to handle user identities/user control/restrictions over specific users etc. Currently we have our own app that handles it but in Web Forms, which does not work with MVC. Number of users is very big and depending on role and position in the Company. App should be able to control who will be able to see specific thing, modify them, restrict other users, adding users, deleting users. etc. etc. long story short - user control/user manager.
So any information or idea about possible solution is very welcome and appriciated. I want to gather as much info as possible to this complex problem.