Centralized master data shared among other several DBs

I'm researching and investigating about all possible ways to create a master data database for my portfolio of applications. To give you a quick overview, an example will come in handy: I want to create a Users database that several different applications will use. Instead of creating user tables in each application I need to centralize in one point all these users data and their permissions, for each application. All this applications have MS SQL server as rdbms, so the Replication engine with a single publisher and several subscribers is an option. However, I would like to know if there are other alternatives, and what's more important, if any of these alternatives could be platform independent (for example, a master DB designed in MySQL with two slaves which could be Oracle and MS SQLServer). Thanks for your help!!