An OAuth proxy is a service that acts as an intermediary between users and backend applications, managing authentication and authorization using the OAuth protocol. It enables applications to delegate user authentication to trusted identity providers, such as Google or Facebook, without handling user credentials directly. The proxy intercepts requests, validates access tokens, and ensures only authorized users can access protected resources. This approach enhances security by centralizing access control, simplifies integration with multiple identity providers, and reduces the risk of credential exposure. OAuth proxies are commonly used in microservices architectures, APIs, and cloud applications to enforce secure, scalable, and consistent access management.