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Sr Principal Software Engineer, AI Security Platform

Northern Trust · Chicago, IL · $164,600–$288,000 a year · Full time

Posted Sep 21, 2026 · We last checked this listing on Oct 6, 2026

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Likely interview questions for this role

Written from this job description, not a generic list. Each one notes what the interviewer is really checking.

About your past

Tell me about a user-facing application you built for developers. How did you make it something they wanted to use?

What they are checking: Whether they can build good front-end experiences, which the posting says the role must cover.

What would you do

A new, better AI model comes out every few months. How would you design the platform so switching models is safe?

What they are checking: Whether they build abstraction and regression testing to swap models without breaking results.

As the platform owner, how do you decide what to build next when security teams and developers want different things?

What they are checking: Whether they can take ownership of priorities and balance needs of different users.

About the work

How would you design an AI-powered code security scanner that finds real vulnerabilities without drowning developers in false positives?

What they are checking: Whether they understand that precision and validation decide whether developers trust a security tool.

How would you validate a vulnerability an AI model reports before showing it to a developer?

What they are checking: Whether they think about confirming findings, which the posting describes as identify, validate and report.

How do you handle the risk that source code sent to a frontier AI model could leak sensitive information?

What they are checking: Whether they consider data protection and vendor controls when integrating outside AI services at a bank.

Walk me through how you would evolve the architecture of a platform like this as the codebase it scans grows to thousands of repositories.

What they are checking: Whether they can plan for scale in cost, throughput and model limits like context size.

How would you measure whether the scanner is actually getting better over time?

What they are checking: Whether they would build evaluation sets and track precision and recall instead of trusting anecdotes.

How do you defend an AI-powered tool against prompt injection hidden in the code it is scanning?

What they are checking: Whether they understand new attack paths that come with putting untrusted input into AI models.

How would you secure the cloud-native infrastructure that runs this platform?

What they are checking: Whether they can protect their own security tool, which would be a high-value target.

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The full job description

As published by Northern Trust.

About Northern Trust As a global leader in innovative wealth management, asset servicing, asset management and banking services, Northern Trust (Nasdaq: NTRS) is proud to guide the world’s most successful individuals, families, corporations and institutions. Since 1889, we have aligned our efforts with our three guiding Principles That Endure: Service, Expertise, and Integrity. Together, they reflect the three cornerstones of business conduct which we strive to instill in our employees, whom we call partners, and to provide to our clients and the communities we serve worldwide. With more than 135 years of financial experience and over 24,000 partners, we serve the world’s most sophisticated clients using leading technology and exceptional service. We are seeking a highly experienced Senior Principal Software Engineer to support technical development of our AI-powered Code Security Scanner platform. This platform leverages frontier AI models and advanced security automation to identify, validate, and report software vulnerabilities across enterprise codebases. This role will be responsible for ongoing development, architectural evolution, and long-term enhancement of the platform. The successful candidate must be equally comfortable designing user-facing applications, building automation, integrating AI services, and securing cloud-native solutions. Platform Ownership • Serve as a lead technical developer for the AI Code Scanner platform. • Implement modernization, enhancements, and scalability initiatives • Mentor junior team members Front-End Development • Improve user experience, reporting dashboards, workflow management, and administrative capabilities • Implement secure authentication and authorization patterns Backend & AI Engineering • Maintain and extend orchestration and scanning services. • Expand and manage integrations with LLM-based security analysis capabilities • Enhance automated vulnerability analysis, reporting, and verification workflows Experience • 15+ years of professional software engineering experience • 5+ years in a lead, principal, or senior engineering role • Experience supporting enterprise-scale applications in regulated environments Technical Skills • Expert-level React development • Modern SPA architecture • REST APIs and authentication integrations • Expert-level Python development • API design and integration • Automation and orchestration frameworks • Test automation and quality engineering • Expert-level Python development • API design and integration • Automation and orchestration frameworks • Test automation and quality engineering • Experience integrating Large Language Models (LLMs) • Agent-based workflows and automation frameworks • Application security and vulnerability management Salary Range: $164,600 - 288,000 USD Salary range is a good faith estimate of base pay. Northern Trust provides a comprehensive benefits package including retirement benefits (401k and pension), health and welfare benefits (medical, dental, vision, spending accounts and disability), paid time off, parental and caregiver leave, life & accident insurance, and other voluntary and well-being benefits. Northern Trust also provides a discretionary bonus program that may include an equity component. Work Authorization Applicants must be authorized to work in the U.S. without the need for employment-based visa sponsorship now or in the future. Northern Trust will not sponsor applicants for U.S. work visa status for this opportunity (no sponsorship is available for H-1B, L-1, TN, O-1, E-3, H-1B1, F-1, J-1, OPT, CPT or any other employment-based visa). Working with Us As a Northern Trust partner, you will be part of a flexible and collaborative work culture, which has a strong history of financial strength and stability. Movement within the organization is encouraged, senior leaders are accessible, and you can take pride in working for a company committed to an inclusive workplace and assisting the communities we serve. Philanthropy is deeply rooted in Northern Trust’s history and is an essential element of our culture. Employees around the world give their time and talent to work for the greater good of their communities. Reasonable Accommodation Northern Trust is committed to working with and providing adjustments to individuals with health conditions and disabilities. If you need a reasonable accommodation for any part of the employment process, please email our HR Service Center at MyHRHelp@ntrs.com , or alternatively you can discuss your individual requirements with the recruiter you are working with.

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