Senior Application Security Engineer

Upstart is an AI lending marketplace focused on reducing the cost and complexity of borrowing through advanced technology. The Senior Application Security Engineer will lead application security projects, partner with engineering and product teams to reduce risk, and build secure-by-default controls, automation, and practices across products, APIs, and AI-enabled systems.

Responsibilities:

• Lead application security projects from planning through implementation, coordinating contributors and dependencies to deliver high-quality outcomes
• Conduct threat modeling and security architecture reviews for complex customer-facing applications, APIs, distributed services, and AI/ML systems
• Design and implement secure-by-default controls across the software development lifecycle, including secure coding standards, API protections, automated testing, CI/CD safeguards, and secrets management
• Partner with engineering teams to identify systemic vulnerabilities, evaluate practical remediation options, and ensure high-risk issues are resolved effectively
• Build services and automation that improve vulnerability detection, prioritization, validation, and prevention while reducing friction for developers
• Assess the security of AI-enabled products and developer workflows, including GenAI integrations, agentic systems, model inputs and outputs, sensitive-data handling, and access boundaries
• Provide technical leadership during high-severity application security incidents, helping determine root causes and drive durable follow-up improvements
• Improve team effectiveness by contributing to design and code reviews, documenting reusable patterns, mentoring engineers, and helping strengthen application security practices across Upstart

Requirements:

• 5+ years of experience in security engineering, software engineering, or a related technical role, including 2+ years focused on application or product security
• Experience leading security projects involving multiple contributors or partner teams
• Experience conducting threat modeling and security architecture reviews for complex production applications
• Experience developing production software or security automation in Java, Python, Ruby, Go, or a similar programming language
• Experience designing or implementing application security controls across the software development lifecycle, including several of the following: API security, secure coding standards, SAST, DAST, SCA, CI/CD security, or secrets management
• Experience identifying, validating, prioritizing, and driving remediation of application vulnerabilities
• Experience securing cloud-native or distributed systems, including web applications, APIs, or microservices
• Experience investigating significant application security issues or incidents and translating findings into corrective engineering work
• This role is available in the following locations: Remote
• The team operates on the East/West coast time zones
• The majority of our employees can live and work anywhere in the U.S or Canada (outside of Quebec)
• Experience building reusable application security guardrails, platforms, or automation adopted by multiple engineering teams
• Experience securing modern frontend frameworks, REST or GraphQL APIs, microservices, and event-driven architectures
• Familiarity with security risks affecting AI/ML and GenAI-enabled systems, including prompt injection, insecure tool use, sensitive-data exposure, and model supply-chain risks
• Experience using risk metrics or program data to prioritize work and measure improvements in application security outcomes
• Experience mentoring security or software engineers and raising quality through design and code reviews
• Experience partnering with Legal, Risk, Compliance, or Audit teams in a regulated environment
• Security certifications such as CISSP, CSSLP, CCSP, AWS Security Specialty, or equivalent practical expertise