Klaviyo is looking for a Senior Security Engineer to add to our growing Detection and Response (D&R) Team. This is a hands-on technical role that involves building and maintaining secure, reliable, and scalable detection and response systems to enhance our security observability capabilities. This role will also be responsible for participating in full end-to-end detection development and response lifecycle and support with threat response operations. As a Senior Security Engineer, you will have the opportunity to leverage your security and engineering skills to provide thought leadership, solve complex security challenges and ultimately improve Klaviyo’s overall security posture. How you will make a difference: Build systems that facilitate security observability for detection and response Develop AI-first security systems to automate detection and response operations Onboard, normalize and optimize security logging data for large-scale data analysis, detection engineering, deployment of ML models, and efficient querying during incidents. Develop high-fidelity rule-based and/or ML-based detections as code Respond to security alerts, cyber threats, and security incidents Drive end-to-end incident response investigations Automate and codify detection and response workflows and processes Conduct ad-hoc threat hunts and be an active member of D&R on-call rotations We’d love to hear from you if you have: 5+ years of experience in software, security, and/or data engineering Automation-first and AI-first approach for all work performed Experience with centralized logging, data lakes, and SIEM solutions Familiarity with large-scale data pipelines and data engineering techniques Proficient in programming languages to automate / build (e.g., Python, Go or similar) Proven experience with git/GitHub and CI/CD automations Familiarity with tactics, techniques, and procedures used by threat actors Experience being part of detection and response or incident response on-call Strong passion for continuous learning and staying updated on evolving technology Strong oral and written communication skills Team player with a strong, self-managing work ethic