Principal Software Engineer, Backend in London

You’ll need the right to work in the UK and be based in London. We are not able to offer visa sponsorship for this role.

About Zapp

We deliver the essentials in minutes, 24/7, from our own network of stores. Every order is a real-time race against the clock, and the systems that win it are the backend you would own. Quick commerce is a genuinely hard backend problem. Stock changes by the second, orders and riders move in real time, and we make sub‑minute promises we have to keep, at high throughput with no room for downtime. Getting that right, fast and reliably, is the job.

We’re AI‑first and we mean it as a way of working, not a slogan: AI‑assisted development is part of the daily toolkit, we ship LLM‑powered features where they genuinely earn their place, and we expect every engineer to shape how we use it.

Backed by the world’s leading investors, built by people who’ve scaled Amazon, Deliveroo, Tesco, Just Eat and Stuart.

Our Leadership Principles

• Creating Magic
• Taking Ownership
• Raising the Bar
• Winning Together
• Delivering with Speed

The role

You’ll be the most senior backend engineer at Zapp, owning the technical direction of the services that run the business, from ordering and inventory to logistics and the platform underneath. This is a hands‑on Principal role: you set the architecture and the standard, and you’re still in the code every week shipping the hardest parts yourself.

You’ll work across the whole backend rather than one corner of it, going where the hardest problem is. You’ll take ownership from a rough problem all the way to production and on‑call, and you’ll lift the engineers around you while you do it. When the team needs a pattern set, a hard call made, or the gnarly bit untangled, that’s you.

What you’ll do

• Set the technical direction. Own the architecture of the backend across services, and make the calls on patterns, boundaries and tooling that the rest of the team builds on.
• Build the hard parts yourself. Design and ship the services, APIs and data models behind ordering, inventory and logistics, and set the standard for what good looks like.
• Raise the bar. Lift the engineers around you through design review, pairing, and the standard you set, and leave the team stronger than you found it.
• Own reliability and scale. Keep high‑throughput, real‑time systems fast and available, and design for the failure modes that come with sub‑minute delivery.
• Own delivery end‑to‑end. Pick up a problem, design the solution, ship it to production, and be on the on‑call rotation that stands behind it.
• Bring AI into how we build. Use AI in your daily work, share the patterns that help the team move faster, and learn from what others discover.
• Help shape AI in our product. Build the backend behind LLM‑powered features, from the data and APIs to the guardrails that keep them safe in production.
• Work across the boundary. Partner with mobile, data and ops engineers on the contracts and systems that tie the product together.

You're a great fit if you

• Experienced. 7+ years building backend systems in production, with real scale behind you.
• Strong in TypeScript. It’s core to our backend and you’re genuinely fluent, not just passing through.
• Polyglot. You’ve shipped production code in more than one language and reach for the right tool for the job.
• Distributed systems depth. You design services, APIs and data models that hold up under real‑time, high‑throughput load.
• Own the data layer. Confident with relational and non‑relational stores, and clear on the trade‑offs between them.
• Lead without a title. You set technical direction and bring people with you through clarity and example, not authority.
• Production minded. Reliability, observability, performance and security are things you design in from the start, not bolt on after the incident.
• Comfortable in uncertainty. You move forward when the path isn’t clear, instead of waiting for someone to define it.
• Test as you build. Automated tests are how you ship code you trust.
• Pragmatic about delivery. You measure your work by what shipped and held up, not the elegance of the design doc.
• Excellent communicator. Clear in how you write and speak, and you love sharing what you learn.

Even better if you know

• GCP. We run on Google Cloud, with Cloud Run, Pub/Sub and Firestore, so familiarity helps you hit the ground running.
• NestJS. Our TypeScript services are built on it.
• GraphQL. We run a federated gateway across multiple subgraphs, so federation experience makes schema and subgraph work easier.
• Event‑driven architecture. Queues, streams and async messaging at scale.
• Infrastructure as code and DevOps. You’re comfortable owning the path to production, not just the code.
• Quick commerce or similar domain. Logistics, on‑demand delivery, or another real‑time, high‑throughput consumer environment.

You're not a great fit if you

• Need a fully defined process and a large, structured team to do your best work.
• Chase architectural purity at the expense of what the business actually needs.
• Stall when the path forward isn’t clear, or wait to be told what to do.
• Want to stay strictly inside one service or specialty and avoid the rest of the stack.

What’s the interview process like?

We aim to make our process clear, respectful of your time, and a real two‑way conversation.

• Stage 1 - Intro call (30 min). A short chat about your background and a chance for us to tell you more about Zapp, the team, and the role.
• Stage 2 - Technical interview (90 min). Live coding and a system design discussion. You’ll have full access to any AI tooling you’d normally use, and we’ll send you a boilerplate repository in advance so you can focus on the problem, not the setup.
• Stage 3 - Values & Leadership interview (60 min). A conversation with senior leadership about how you work, what you care about, and how you align with our Leadership Principles.
• Stage 4 - Offer. We will need to verify your right to work in the UK before extending an offer.

Generous salary & equity package

• 25 days holiday per year, plus all bank holidays
• Private health insurance
• Extended sick pay and enhanced maternity and paternity leave
• Cycle to work scheme
• Budget for learning, conferences and kit