Senior Security Engineer - AI Products & Platforms in London

Discover your future at Citi. Working at Citi is far more than just a job. A career with us means joining a team of more than 230,000 dedicated people from around the globe. At Citi, you’ll have the opportunity to grow your career, give back to your community and make a real impact.

We are Citi’s Application, Platform and Engineering team, a start‑up with the exciting mission of shaping the direction of travel for the entire bank under the Chief Technology Office, by defining the tech and engineering strategy for the bank. We are a team of talented engineers, product managers and tech SMEs, taking ambiguous concepts and making them real by engineering cutting edge products at planetary scale! We are solely focused on the most modern technology and engineering disciplines such as generative AI, cloud, security, modern app stacks (with Golang, Gatekeeper), open source and the latest and greatest in the Kubernetes ecosystem.

You might be a good fit if you:

• Bring your deep‑dive application security engineering expertise from building production systems
• Thrive in a results‑driven environment, where flexibility fuels impact
• Be a game‑changer, ready to step beyond your designated role
• Love the synergy of pair programming? Seize the opportunity to secure AI applications at scale.
• A relentless passion to learn more about AI security, LLM attacks, and bringing your knowledge to shape Citi’s secure AI future.

What you’ll do within the Tech Strategy team:

• Build secure AI products from 0‑1 – Engineer production‑grade, business‑facing AI platforms with security built‑in from day one
• Ethical hacking and red team activities – Conduct penetration testing, vulnerability research, and attack simulation to make our products bulletproof
• Design and build security tools and frameworks – Create automated security solutions that scale across fast‑paced development cycles
• Secure novel AI attack surfaces – Identify and mitigate LLM‑specific vulnerabilities, prompt injection attacks, and AI model security risks through hands‑on testing
• Lead "shift left" security – Embed security practices throughout our rapid development lifecycle while maintaining velocity
• Mentor security practices – Guide other engineers on secure coding, vulnerability remediation, and security‑first thinking

Experience That Will Help You Succeed In This Role:

• Production system builder with security focus – proven track record of architecting and building secure, large‑scale production applications and business‑facing platforms from the ground up
• Ethical hacking and penetration testing expertise – hands‑on experience finding and exploiting vulnerabilities, conducting red team exercises, and thinking like an attacker to strengthen defenses
• State‑of‑the‑art security engineering with Go, Python, JavaScript – you build both security tools and secure production systems in fast‑paced environments
• HashiCorp Vault mastery – deep experience writing custom plugins, creating secret engines, implementing dynamic credentials, and extending Vault functionality for enterprise‑scale secrets management
• Enterprise authentication & authorization – designing and implementing OAuth, JWT, RBAC, and complex identity systems with fine‑grained access controls in business‑critical applications
• API security and threat modelling – securing REST/GraphQL APIs, conducting threat assessments, and implementing advanced security patterns in high‑traffic production systems
• AI/ML security and vulnerability research – understanding of LLM vulnerabilities, model security, prompt injection attacks, and AI‑specific threat vectors through hands‑on testing
• Security automation and tooling – automating manual security processes
• Cloud‑native security – securing containerized applications in Kubernetes, service mesh security, and cloud‑native security patterns at enterprise scale
• Incident response and forensics – experience investigating, analyzing, and responding to security incidents in live production systems

What We Believe In:

We do not have boundaries between security engineering and product development, and we expect all our technical staff to contribute to both as needed. We take a product‑focused approach to security and care about building solutions that are robust, scalable, and easy for developers to use. We enjoy working in a fast‑paced team tackling cutting‑edge security problems by constantly testing and learning. We enjoy pair programming for our security tools; we are lean in our approach and remove bureaucracy where we see it. We believe in delivering secure solutions fast, iterating and pivoting as we go, rather than defining the perfect security framework upfront.

What we’ll provide you:

This is a unique role that will put you in the position to be part of a new venture and actively drive change. Every day there will be new challenges that will help you develop new skills that can drive your career. By joining Citi London, you will not only be part of a business casual workplace with a hybrid working model (up to 2 days working at home per week), but also receive a competitive base salary (which is annually reviewed), and enjoy a whole host of additional benefits such as:

• 27 days annual leave (plus bank holidays)
• A discretionary annual performance related bonus
• Private Medical Care & Life Insurance
• Employee Assistance Program
• Pension Plan
• Paid Parental Leave
• Special discounts for employees, family, and friends

Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law.