London: Principal Engineer

Location: Waterloo, London, England, UK | Hybrid (1 day per week in office)

Who We Are

At 8th Light, we bring life to the best ideas. Founded in 2006 and headquartered in Chicago, we are a technology solutions provider that partners with organizations to solve meaningful challenges and drive sustainable growth. From early-stage startups to global enterprises, we work across industries to optimise our clients’ digital products through product strategy innovation, experiential design, AI solutions, and deep engineering expertise. Our commitment to quality means we deliver solutions we’re truly proud of, while our curiosity sparks innovation and breakthrough thinking. 8th Lights thrive in an environment that champions continuous education, fueling our growth through mentorship and hands-on work. We foster an open, collaborative culture grounded in honesty that builds trust, and believe true success is measured by the outcomes we create for our clients.

Who You Are

You’ve shown long-term repeated success on a variety of projects, typically over the course of 10+ years. You are a trusted expert and leader, often called upon to guide ambiguous initiatives and architect scalable solutions. You bring a blend of deep consulting acumen, technical expertise, and product thinking that drives measurable and impactful outcomes. In your previous experience, you have:

• Demonstrated long-term success on high-stakes consulting engagements across multiple language paradigms, stacks, ecosystems, technical environments, and client industries.
• Built high-quality, maintainable software collaboratively, incrementally, and through an approach tailored towards the unique needs of the clients you’ve served.
• Led the development and delivery of production-grade software using a variety of languages and frameworks, including but not limited to: Python, Java, JavaScript, TypeScript, React, Ruby, Scala, R, SQL, and Go.
• Evaluated and strategically applied AI-assistive development tools to accelerate delivery and improve quality.
• A track record of understanding, assessing, and embracing new tooling and trends within the software industry.
• Experience building or integrating AI/ML-powered features into products or systems (e.g., recommendation engines, NLP models, computer vision, predictive analytics).
• Used context-appropriate automated testing to inform software design choices and catch bugs.
• Successfully led modernization efforts to align legacy systems with short and long-term business needs.
• Remedied architecture-level concerns such as scalability, security, reliability, and performance.
• Facilitated alignment and collaboration across technical and non-technical stakeholders to move initiatives forward in the face of ambiguity and complexity while balancing technical considerations with product and user needs.
• Provided mentorship and team support at scale, while sharing knowledge and improving team practices.
• Actively sought out and effectively given feedback.
• Collaboratively led stakeholders to balance technical considerations with product and user needs.

What You’ll Do At 8th Light

As a go-to technologist and strategist within 8th Light, you’ll work with a variety of clients, typically one to two in a year, while continuing to deepen your and our collective domain expertise over the course of your career with us. You’ll be responsible for:

• Rapidly building trust with clients, demonstrating technical expertise and understanding of their domain and objectives.
• Guiding technical direction, solving complex problems, and demonstrating best practices while remaining deeply engaged within the codebase.
• Working pragmatically to balance technology choices while delivering high-quality work within deadlines.
• Advising clients on architecture, scalability and platform evolution, connecting technical decisions to product and business outcomes.
• Collaborating on systems that involve the full ML lifecycle from data ingestion and preprocessing, to model deployment, integration, and performance monitoring.
• Driving innovation by proactively surfacing new technical approaches and product solutions.
• Leading or initiating formal feedback conversations with teams and clients via retrospectives.
• Clearly articulating and documenting outcomes and driving forward action items.
• Contributing to the health of your team and 8th Light’s culture by modelling our Values.
• Designing and managing high-level technical roadmaps for large engagements.
• Building your network and maintaining relationships with clients and other industry leaders within your domain.
• Coaching client engineering teams, transferring knowledge and leveling up practices.
• Influencing client CTOs and executive decisions.
• Planning and executing technical work that involves stakeholders outside of project boundaries such as across a client's technical organization.
• Participating in account planning; opportunity identification.
• Facilitating retrospectives, strategy sessions, and technical deep-dives to improve team and project outcomes.
• Identifying, mitigating, and resolving blockers to team progress.
• Contributing to 8th Light by serving as a mentor, leading or designing workshops internally or for clients, representing 8th Light in the tech community, or supporting our hiring processes.
• Demonstrating leadership in scalable system design, modular architecture, and platform- or product-oriented development.
• Bringing depth in testing strategies, observability, fault tolerance, and secure engineering practices.
• Applying architectural patterns to evaluate tradeoffs and drive clear, documented design rationale.

Strongly Preferred Skills

We work across many areas, and encourage anyone with the experience listed above to apply. We would particularly like to encourage applicants with experience in the following areas:

• Delivering and advising on enterprise-grade AI systems, including RAG pipelines, vector search, and agentic frameworks (e.g., LangChain, LlamaIndex, Crew AI, AutoGen, n8n), ensuring scalable, production-ready solutions that empower developers and align with business outcomes.
• DevSecOps.