集中管理多个应用程序的用户

I want to centralize all web applications users into one box, i have .Net applications & PHP applications, mostly the users are 90% the same. i want the applications to call this centralize system to validate the user, return the application roles or return denied status if invalid.

I had checked Sentinel & UserSpice tools, they seems work like a plugin/framework, not yet support APIs.

Is there any other tools i can use (Not yet to cloud environment), or SAML with SSO is the only way to implement it?

is it a quick & simple idea i use any php framework like Cakephp/Laravel to build the user management frontend, and build my own api to validate user & return the role value back to applications?

Thanks