Staff Application Security Engineer

Brex is the intelligent finance platform that enables companies to spend smarter and move faster in more than 200 markets. As a Staff Application Security Engineer, you will define the technical vision and long-term security architecture for the Brex platform, serving as the technical leader for the Application Security team and driving the strategic direction of secure product lifecycle and vulnerability management programs.

Responsibilities:

• Lead the technical vision and strategic roadmap for the Application Security team, aligning security objectives with Brex's enterprise growth and high-velocity engineering metrics
• Establish technical standards and secure defaults across the entire engineering organization, fostering a culture of collaborative security excellence and bridging product platforms, infra, and trust
• Architect and secure novel AI/ML and agentic workflows, applying cutting-edge practices to mitigate risks such as prompt injection, model manipulation, and data poisoning
• Mentor and coach engineers within the team and across the broader organization, guiding technical growth, helping individuals level up their security expertise, and accelerating team delivery
• Drive proactive vulnerability discovery and offensive security testing strategies, executing complex attack chains to demonstrate business impact and prioritize cross-functional remediation
• Partner with Product Platform, Cloud Infrastructure, and Data engineering teams to ensure core primitives, APIs, and microservices are secure by default from design to deployment

Requirements:

• 8+ years of experience in Application Security, Product Security, or software engineering with a primary focus on offensive and defensive application security
• Proven track record of technical leadership and team mentorship on complex, multi-quarter security engineering initiatives in a fast-paced environment
• Deep proficiency and technical expertise in AI security, including hands-on experience securing agentic architectures, LLM gateways, and evaluating adversarial AI vectors
• Strong systems-thinking capabilities with extensive experience defining secure product development lifecycles, threat modeling complex topologies, and cloud-native container security (AWS, Kubernetes)
• Proficiency in Python, Go, or similar languages to architect internal tooling, pipeline automation, and advanced detection/scanning engines
• Exceptional written and verbal communication skills, with a demonstrated ability to navigate ambiguity, influence technical leaders, and manage up and out across EPD organizations
• Experience with Kotlin, gRPC, GraphQL, Kubernetes
• Previous experience in building and scaling security teams
• Experience with securing distributed systems in AWS and cloud environments
• Contributions to the wider technical community — open source, public research, CTF participation, blogging, CVEs, or presentations
• Experience submitting to bug bounty or responsible disclosure programs
• Published AI security research or contributions to AI security frameworks