Abstract:
Authentication in microservice architectures (MSA) is hard because services are spread out. Managing user identities is tricky. Keeping communication between services secure is important. Controlling access to APIs is also complex. It is more challenging than in traditional monolithic systems. The main goal of this study is to review and compare existing authentication mechanisms for microservices to identify effective and scalable solutions. This review uses a structured narrative method, analyzing recent research and technologies such as JSON Web Tokens (JWT), session-based authentication, Single Sign-On (SSO), passwordless, and biometric approaches. The findings show that token-based methods like JWT improve scalability and user experience but are vulnerable to token theft. Session-based systems offer stronger central control but struggle to scale in large networks. Passwordless and SSO solutions enhance usability but still require strong security controls. This review compares different authentication methods clearly. It describes the pros and cons of each system. It also explains how new trends like zero-trust, adaptive, and decentralized authentication may change the future. These trends help make microservice systems more secure and scalable
