Perform application security reviews, code and design reviews, threat modeling, and secure SDLC initiatives. Implement and maintain CI/CD security controls (SAST/DAST/SCA/secret/IaC/container scanning), remediate vulnerabilities, support pen tests and audits, tune detection and monitoring (Elastic SIEM, WAF), participate in incident response and on-call rotation, and advise engineering on secure architecture, API/security patterns, and secrets management.