Senior Full-Stack Engineer at Pixie Labs in London

Pixie Labs is a boutique technology consultancy specialising in building and strengthening the systems behind ambitious health and wellness brands. We partner with growing teams to untangle complex platforms, enhance operational resilience, and establish the technical foundations necessary for scaling with confidence. Founded in 2013, with offices in London and New York, we’ve grown organically year on year, working with clients who value deep technical expertise and long‑term impact.

The role involves working on the systems that sit at the heart of scaling health and wellness businesses, helping untangle fragile platforms, improve reliability, and create foundations that support long‑term growth. You’ll bring 5+ years of commercial software engineering experience, strong generalist skills, and hands‑on experience with Ruby on Rails, with the confidence to work across the full lifecycle from technical discovery and system design through to delivery, deployment, and ongoing optimisation.

You’ll take a leading role on client engagements, owning technical direction and delivering high‑quality, maintainable systems. Alongside this, you’ll contribute to a strong engineering culture by sharing knowledge, challenging assumptions, and supporting others to raise the bar. You’ll apply your technical expertise throughout each engagement, from auditing existing platforms and shaping realistic delivery plans to hands‑on implementation, testing, deployment, and long‑term support.

If you’re entrepreneurially minded and motivated by ownership, autonomy, and impact, you’ll feel at home in our team. And if you enjoy mentoring and developing other engineers, there’s plenty of scope to do that as part of the role.

At Pixie Labs, we offer a range of benefits to help you balance personal growth, work, and life:

• A strong focus on personal development, including a development plan, regular 1:1s, and reviews.
• A 5% employer pension contribution, with flexibility for employees to increase their own contributions.
• Private health insurance via Vitality, with optional cover for dependants and access to wellbeing perks.
• All the tools you need, including a generous LLM token budget, a high‑spec MacBook, peripherals, and ergonomic equipment.
• Support for training, conferences, and learning materials, approved on a case‑by‑case basis.
• All the usual perks: cycle‑to‑work scheme, tech scheme, and season ticket loan.

Experience and skills required include:

• Demonstrable experience owning projects from start to finish, working cross‑functionally with peers and leaders, while acting as a consultant as much as a senior engineer.
• Strong experience building and maintaining production systems using Ruby on Rails, with the ability to reason about trade‑offs, constraints, and long‑term maintainability.
• A solid grounding in system design and architecture, including working with relational databases, integrations, and data‑heavy or business‑critical workflows.
• Experience in diagnosing existing platforms and improving them, whether through refactoring, performance work, platform modernisation, or targeted rebuilds.
• Comfort working across the full delivery lifecycle, from technical discovery and estimation through implementation, deployment, and ongoing support.
• Experience collaborating closely with non‑technical stakeholders, explaining technical decisions clearly, and aligning engineering work with business goals.
• A pragmatic approach to quality, including testing strategies, code review, and incremental improvement rather than a dogmatic process.
• Familiarity with modern front‑end development (e.g. React, Svelte), and how front‑end and back‑end concerns interact in real systems.
• Confidence working in small teams with a high degree of ownership, autonomy, and responsibility.

Some fine print: Candidates must have the right to work in the UK; we cannot provide visa sponsorship. As a small, fast‑paced team in regular communication with clients, we can’t accommodate someone working compressed hours (e.g. long days Mon‑Thu).

Interview process includes an intro call with the CTO, an interview with the founder, an on-site technical pairing interview, a chat with a member of the engineering team, and a final interview with both the founder and the CTO.