Principal Engineer

Principal Engineer — London | Mobile-First AI Scale-Up | Hands-On Role

We're supporting a high-growth, mobile-first technology company in London as they enter a new phase of scale. They are looking for a Principal Engineer who can combine deep technical capability with architectural oversight, helping shape and deliver the systems at the core of their AI-driven product.

This is a genuinely hands-on technical leadership position. You'll work closely with the CTO, influence engineering direction, and ensure the company continues to innovate while scaling reliably and efficiently. The environment suits someone who's comfortable operating in a fast-moving, product-focused organisation where technical decisions directly influence outcomes.

What you'll be doing

• Partnering with the CTO to refine and execute the engineering strategy and long-term technical roadmap.
• Leading the architecture, design, and delivery of AI-powered systems across mobile, backend, and data.
• Remaining deeply hands-on: understanding challenges first-hand, guiding engineers, and contributing to critical builds.
• Ensuring alignment and cohesion across iOS, Android, backend services, data, and AI platforms.
• Driving technical excellence across code quality, data integrity, system performance, and operational resilience.
• Working closely with product and data teams to ensure AI initiatives deliver measurable business value.
• Hiring, mentoring, and helping develop high-performing engineering teams.

What you'll need

• Strong engineering fundamentals and experience solving complex technical problems.
• Proven ability to design, build, and scale software systems in a start-up or scale-up environment.
• Hands-on experience with Go, Rust, or Python.
• Strong cloud experience with AWS or GCP.
• Solid understanding of native mobile platforms (iOS and/or Android).
• Experience working with or building AI/ML-driven systems.
• Broad technical literacy across backend, data, and mobile domains.
• Commercial awareness — you understand how engineering decisions influence product and business goals.
• Experience contributing to or leading teams.
• Not suitable for candidates whose recent experience is in large enterprises, banking, or heavily structured corporate environments. The company is looking for engineers who understand the pace, ambiguity, and ownership expected in high-growth technology businesses.

Why this role?

You'll have the opportunity to influence architectural direction, work directly with executive leadership, and contribute to systems used by millions. It's a role for someone who wants to stay close to the engineering craft while shaping the next phase of a rapidly scaling product.

About Burns Sheehan

Burns Sheehan is a specialist technology recruitment partner with over 20 years' experience supporting London's start-up and scale-up ecosystem. We connect high-potential companies with the engineering talent they need to grow, working closely with founders and technical leaders to build exceptional teams.