Design, review, and assess OAuth 2.0 and OpenID Connect flows, including authorization code with PKCE, refresh tokens, client authentication, scopes, consent, state, nonce, redirect URI validation, token lifetimes, and key rotation. Experience with web and API security risks, including OWASP Top 10, OWASP API Security Top 10, broken access control, SSRF, injection, XSS, CSRF, insecure deserialization, request forgery, misconfiguration, and supply-chain risk.