Fastify OpenID Connect Authentication

fastify-openid-auth is a specialized Fastify plugin designed to streamline OpenID Connect (OIDC) authentication within a Fastify application. Leveraging the robust openid-client library, it offers comprehensive support for both bearer token and cookie-based authentication flows, providing flexibility in how authentication state and tokens are managed. The plugin currently operates at version 12.0.0 as of its latest significant update in late 2025, demonstrating a consistent and active development cadence with several minor and major releases throughout 2024 and 2025. Key differentiators include its deep integration into the Fastify ecosystem by decorating the Fastify instance with dedicated `login`, `verify`, `refresh`, and `logout` handlers, full TypeScript type definitions, and adaptable token reading/writing strategies via headers, cookies, or session storage, making it suitable for a wide range of web application and API authentication scenarios.