The blog post delves into the implementation of OpenID Connect (OIDC) authorization code flow for client authentication in Couchbase Sync Gateway, emphasizing its application in Couchbase Lite client apps and web/mobile applications. It outlines the configuration requirements for enabling OIDC on a per-database basis, including the setup of a basic OIDC config for authorization code flow, and highlights the steps involved in the authentication process, such as initiating the flow through the Sync Gateway, retrieving and validating tokens, and creating user sessions. The post also explores the benefits of the authorization code flow, notably its enhanced security through the use of client_id and client_secret, and the ability for clients to refresh tokens without requiring user reauthentication. Additionally, it explains how access grants can be managed for authenticated users, either dynamically through Sync Gateway's APIs or statically via the admin REST API, and suggests utilizing backend servers for more complex access grant assignments. The article concludes by discussing the comparative advantages of both implicit and authorization code flows while providing resources for further exploration of OIDC support in Sync Gateway.