Senior Security Engineer, Detection & Response

Compensation:

The salary range for this role is $5,000 - $9,500 per month (Gross in USD), based on experience level and gross amount. This range reflects the expertise, leadership capabilities, and significant contributions expected at the principal level.

About Sezzle:

With a mission to financially empower the next generation, Sezzle is revolutionizing the shopping experience beyond payments, blending cutting-edge tech with seamless, interest-free installment plans that make shopping smarter and more accessible. We are building an innovative, dynamic team passionate about creating a truly unique shopping journey.

About the Role:

We are seeking a hands-on, high-impact Senior Security Engineer, Detection & Response, to strengthen security operations at Sezzle: detection, incident response, and vulnerability management across our cloud infrastructure and applications.

You will join the team that runs our SIEM and detection capability, from log ingestion and audit coverage to detection rules, alert tuning, and investigation workflows. You will operate the vulnerability-management loop end-to-end, and when incidents happen, you will lead the investigation and see the long-term fix through.

You will report to the Director of Information Security and work alongside the engineers who own the security platform and network and zero trust. This role is ideal for someone who thrives in a fast-paced environment and wants to work on real-world security problems at scale. AI-assisted engineering is a standard part of how we work, including agentic workflows for alert triage, investigation, and threat hunting.

What You'll Do:

• Build, operate, and mature SIEM/XDR capabilities, including log ingestion, detection rule development, alert tuning, and investigation workflows
• Design and implement detection strategies for suspicious activity, including data exfiltration patterns using application and database telemetry
• Extend audit and attribution coverage across the estate, including Kubernetes audit logs, database audit logging, SSO and access-path telemetry, with retention aligned to compliance requirements
• Investigate and respond to security incidents across cloud infrastructure and applications, performing root cause analysis and driving long-term fixes
• Run proactive threat hunts across cloud and identity planes, building agentic hunting workflows that make hunts repeatable
• Operate vulnerability management across infrastructure, platforms, and applications, including internal scans, dependency analysis, and external findings, validating true positives and driving remediation with engineering teams
• Triage and validate external security findings (including bug bounty reports), distinguishing true positives and coordinating remediation
• Contribute to threat modeling and security design reviews for the detection, logging, and incident-response implications of new systems
• Apply strong AWS and Kubernetes judgment to secure the systems you operate and advise owning teams on remediation
• Support and implement security controls aligned with PCI DSS, SOC 2, and other compliance requirements, with your logging and detection work producing the audit evidence as a by-product
• Develop and implement automation (including AI) to improve efficiency in security operations, detection, and response
• Participate in the on-call rotation for detection and response and the services you own

What We Look For:

• 6+ years of experience in security, software, or infrastructure engineering, with hands-on experience securing cloud-based production systems
• Experience working with SIEM platforms (e.g., Wazuh, Splunk, ELK) for detection engineering, monitoring, and incident response
• Experience designing and tuning detection rules, reducing alert noise, and improving investigation workflows
• Strong hands-on experience in vulnerability management, including scanning, triage and validation of scanner and bug-bounty findings, remediation coordination, and verification
• Strong knowledge of AWS, Linux, and Kubernetes infrastructure, including security architecture and operational best practices
• Ability to investigate issues directly using logs, cloud tooling, and system-level data
• Experience assessing the detection and logging implications of new systems in design reviews
• Knowledge of common security vulnerabilities and mitigation strategies (OWASP, SANS, etc.)
• Working knowledge of compliance frameworks such as PCI DSS and SOC 2, particularly logging, monitoring, and evidence expectations
• Demonstrated AI-forward engineering: you actively use AI tooling (e.g., Claude Code, Codex, Cursor, or custom LLM integrations) and have opinions grounded in practice about where it helps and where it does not

Preferred Knowledge and Skills:

• You have built AI-assisted workflows that others adopted, such as triage, enrichment, or hunting
• Familiarity with log-based detection, telemetry pipelines, and security analytics use cases
• Experience with internal penetration testing or adversarial exercises, and translating results into detection and remediation work
• Strong understanding of cloud-native security controls, including IAM, network segmentation, and container security
• Experience with container and dependency security tools (e.g., Snyk, Trivy, Grype) as an operator of their findings
• Experience aligning technical security work with regulatory and compliance expectations
• Experience in fintech, payments, or other regulated environments

About You:

• You think like an investigator. You turn telemetry into detections and detections into answers, and you are not done until the root cause is fixed.
• You treat attribution as an engineering deliverable. Every access to sensitive data has a name on it, and every finding has an owner and a date.
• You are excited to use automation and emerging technologies (including AI) to take repetitive security work off the team's plate.
• You balance strong security standards with business needs and can support privacy and compliance requirements in a practical, scalable way.
• You have relentlessly high standards. You make sure that defects do not get sent down the line and that problems are fixed so they stay fixed.
• You are not bound by convention. Your success lies in developing new ways to do things.
• You need action. Speed matters in business, and you value calculated risk-taking.
• You earn trust. You listen attentively, speak candidly, and treat others respectfully.
• You have backbone. You respectfully challenge decisions when you disagree, and once a decision is determined, you commit wholly.
• You deliver results. You focus on the key inputs, deliver them with the right quality and in a timely fashion, and never settle.

Sezzle's Technology Stack:

• Languages: Golang, TypeScript, Python
• Frontend: TypeScript, React and React Native
• Backend: Golang
• Database: MySQL, Postgres, Elasticsearch
• DevOps & Cloud: AWS, Kubernetes
• Version Control: Git
• CI/CD: GitLab
• Testing: Developer and AI-driven, focus on automated end-to-end, integration, and unit tests
• Open Source: Sezzle is focused on using open source, and we build what we can before buying

What Makes Working at Sezzle Awesome?

At Sezzle, we are more than just brilliant engineers, passionate data enthusiasts, out-of-the-box thinkers, and determined innovators. We believe in surrounding ourselves with the best and the brightest individuals, those who are unique and purpose-driven in all that they do. Our culture is defined by the visible example living in every employee that we hire.