Principal AI Engineer

Principal AI Engineer

Role Summary

Serve as a principal engineer driving end‑to‑end design, development, and delivery of scalable, secure, high‑performance software and AI solutions. Combine deep engineering expertise with hands‑on Large Language Model (LLM) integration, prompt engineering, and engineering leadership.

What You'll Do

Software Engineering

• Design and implement complex services and platforms.
• Write clean, maintainable, well‑tested code (Java, Python, plus other high-level languages).
• Perform performance tuning and root‑cause analysis of critical issues.

AI & Machine Learning Leadership

• Design and refine prompt engineering strategies for production LLM applications
• Integrate, optimize, and evaluate LLMs working with retrieval‑augmented generation (RAG), Agentic AI, embeddings, vector databases and prompt management tools
• Lead model selection, fine-tuning, and deployment strategies for financial use cases
• Build and maintain AI evaluation frameworks and automated testing pipelines

Performance & Reliability

• Champion observability, AI Ops, and real-time monitoring across distributed systems
• Drive resilience patterns (circuit breakers, retries, graceful degradation) for 99.99% uptime
• Design cost-effective AI infrastructure optimized for latency and throughput

Technical Leadership & Mentorship

• Partner with Product, QA, Architecture, Data Science, and Compliance teams
• Conduct technical design reviews and elevate engineering standards across the organization
• Mentor senior engineers and lead architectural decisions; model technical excellence
• Drive technical strategy for AI adoption across multiple product lines

Innovation & Research

• Track emerging AI/ML frameworks, techniques, and tooling
• Prototype and assess new approaches for production adoption
• Build proof-of-concepts that demonstrate business value and technical feasibility

Quality & Compliance

• Enforce automated testing, CI/CD, and secure coding
• Advocate for infrastructure-as-code and continuous improvement practices

Qualifications & Experience

• 12+ years professional software engineering.
• 1+ year hands‑on AI / LLM solution development.
• Proven delivery of complex, high‑impact systems.
• Extensive experience in system and application architecture.

Technical Skills

• Languages: Expert in Java and Python; exposure to additional modern languages.
• Architecture: Distributed systems, microservices, API design, event-driven patterns.
• AI / LLM: Prompt engineering, evaluation, fine‑tuning, embeddings, RAG, model deployment.
• Data: Vector stores, caching, streaming, persistence strategies.
• Tooling: Prompt management (Langfuse), experimentation frameworks.
• Cloud: AWS, Azure, or GCP (designing secure, scalable workloads).
• DevOps: CI/CD pipelines, containerization (Docker), orchestration (Kubernetes), infrastructure-as-code.
• Security: Identity, secrets management, secure SDLC practices.
• Observability: Metrics, tracing, log aggregation, SLO/SLA design.

Core Competencies

• Advanced analytical and problem-solving ability.
• High technical ownership with pragmatic decision-making.
• Clear, concise technical communication.
• Continuous improvement mindset and innovation bias.
• Ability to operate independently while enabling team success.

Nice to Have

• Hands-on experience building AI infrastructure (evaluation pipelines, prompt/version management, vector/embedding stores, model serving) and optimizing / fine‑tuning models for latency, quality, and cost.
• Experience with model evaluation harnesses and automated prompt regression.
• Background in cost optimization for AI workloads.
• Contributions to open-source or technical publications.

Impact Measures

• Code quality and architectural longevity.
• Performance and reliability metrics.
• AI feature delivery velocity and model effectiveness.
• Security and compliance adherence.
• Mentorship and uplift of engineering practices.

Career Stage:

London Stock Exchange Group (LSEG) Information:

Join us and be part of a team that values innovation, quality, and continuous improvement. If you're ready to take your career to the next level and make a significant impact, we'd love to hear from you.

LSEG is a leading global financial markets infrastructure and data provider. Our purpose is driving financial stability, empowering economies and enabling customers to create sustainable growth.

Our purpose is the foundation on which our culture is built. Our values of Integrity, Partnership, Excellence and Change underpin our purpose and set the standard for everything we do, every day. They go to the heart of who we are and guide our decision making and everyday actions.

Working with us means that you will be part of a dynamic organisation of 25,000 people across 65 countries. However, we will value your individuality and enable you to bring your true self to work so you can help enrich our diverse workforce.

We are proud to be an equal opportunities employer. This means that we do not discriminate on the basis of anyone's race, religion, colour, national origin, gender, sexual orientation, gender identity, gender expression, age, marital status, veteran status, pregnancy or disability, or any other basis protected under applicable law. Conforming with applicable law, we can reasonably accommodate applicants' and employees' religious practices and beliefs, as well as mental health or physical disability needs.

You will be part of a collaborative and creative culture where we encourage new ideas. We are committed to sustainability across our global business and we are proud to partner with our customers to help them meet their sustainability objectives. Our charity, the LSEG Foundation provides charitable grants to community groups that help people access economic opportunities and build a secure future with financial independence. Colleagues can get involved through fundraising and volunteering.

LSEG offers a range of tailored benefits and support, including healthcare, retirement planning, paid volunteering days and wellbeing initiatives.

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