OAuth 2.0 and OpenID Connect authentication with secure flows. Use for third-party integrations, SSO systems, token-based API access, or encountering authorization code flow, PKCE, token refresh, scope management errors.

OAuth Implementation Implement OAuth 2.0 and OpenID Connect for secure authentication. OAuth 2.0 Flows Flow Use Case Authorization Code Web apps (most secure) Authorization Code + PKCE SPAs, mobile apps Client Credentials Service to service Refresh Token Session renewal Authorization Code Flow (Express) PKCE for Public Clients Security Requirements Always use HTTPS Validate redirect URIs strictly Use PKCE for public clients Store tokens in HttpOnly cookies Implement token rotation Use short lived access tokens (15 min) Additional Implementations See [references/python java.md](references/python java.md) for: Python Flask with Authlib OIDC provider OpenID Connect discovery and JWKS endpoints Java Spring Security OAuth2 server Token introspection and revocation Never Do Store tokens in localStorage Use implicit flow Skip state parameter validation Expose client secrets in frontend Use long lived access tokens

oauth-implementation