Identity Server4 is an authentication provider. It is an open-source OpenID Connect and OAuth2.0 framework for ASP.NET Core. The main objective of OpenID Connect is to centralize the authentication process. This centralized authentication provider or Security token server (STS) is a great solution for the application working with more than 2 APIS/microservices where you don’t want to use a different authentication provider for each service. From IdentityServer4, you will get centralized access control to secure every API by the central Identity Server. Mainly the STS is responsible for issuing tokens and validating claims.
Identity Server4 provides the flexibility to use external storage like a relational database, NoSQL, a file system, or in-memory data storage. NCache, being a distributed and scalable in-memory key-value data store, is a great fit for IdentityServer4. This article will teach you how to use NCache as external in-memory storage for identityServer4. You may get a question here, why is external in-memory storage required? Using external in-memory storage like NCache will improve the application performance and will give you a faster result.