Security Software Engineer

Join Modern Treasury, a company dedicated to building the most trusted financial infrastructure for global money movement. As a Security Software Engineer, you will design and strengthen the controls that protect our payment infrastructure, enabling the development of secure and compliant financial products. This hands-on role focuses on application, product, and infrastructure security, and will have a direct impact on the reliability and automation of our security and infrastructure systems.

• Lead application security across the payment platform, including secure code review, threat modeling, and security architecture for new products.
• Own product security for new payment rails, including FBO account structures, stablecoin integration, and enhanced compliance features.
• Design and implement DevSecOps tooling and automation to improve security posture across CI/CD and infrastructure.
• Knowledge and experience with application security for Ruby on Rails, GraphQL, JavaScript, React, and containerized environments
• Secure SDLC practices and developer security tooling
• Payments engineering experience, ideally including fraud prevention and risk controls in money movement systems
• Strong experience with:
• Authentication and authorization systems and identity management
• Fraud detection, prevention, and abuse mitigation in payment or financial products
• Experience with incident response and security monitoring
• Infrastructure automation related to security (AWS, Docker, CI/CD pipelines)
• Full-stack application security (frontend, backend, APIs)
• 6+ years in security engineering, with 3+ years focused on application and product security
• 2+ years in payments or fintech, with a deep understanding of money movement security challenges
• Familiarity with compliance and regulatory standards for money movement, such as PCI DSS, BSA/AML, and KYC/KYB
• Experience with payment processing security across ACH, wires, card networks, and emerging rails
• Experience building controls for fraud detection, chargeback prevention, and abuse mitigation in payment systems
• Experience integrating security into DevOps workflows (e.g., Buildkite, IaC, AWS security automation)
• Experience with stablecoin security, blockchain integrations, or crypto payment rails
• Demonstrated ability to lead security initiatives across multiple teams without direct authority
• Track record of balancing pragmatic risk management with business velocity