Senior Product Engineer, React Native

Justzapp; Greater London; On-site; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Equity package

25 days holiday

Private health insurance

Extended sick pay and parental leave

Job summary

Justzapp in London Nine Elms is seeking a senior mobile engineer to own the end-to-end mobile experience. You’ll build the iOS, Android and web apps in React Native and Expo, delivering fast, reliable features for our 24/7 on-demand service.

You’ll bring 5+ years of production software experience, deep TypeScript skills, and a production-minded mindset. We value curiosity, collaboration, and comfort with uncertainty as you help shape AI-driven product features.

Qualifications

• 5+ years building production mobile apps.
• Strong TypeScript fundamentals.
• Experience with React Native and Expo.

Responsibilities

• Build mobile and web experiences in React Native and Expo across iOS, Android, and web.
• Integrate AI-driven features into the product.
• Own on-call and production health.
• Collaborate with backend and design teams.

Skills

React Native

Expo

TypeScript

Mobile development

iOS

Android

Tools

NestJS

GraphQL

GCP

Firestore

Firebase

Job description

Overview

Location: Nine Elms, London. Full time, hybrid with at least 3 days a week on site.

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

Zapp is building the future of convenience with a full stack approach to on-demand essential items, 24/7, delivered in minutes. Customer obsession is at the heart of everything we do, from app users to frontline staff to store workers. We are relentlessly focused on delighting our customers.

We are backed by the world\'s leading investors, and our team has scale-up and exit experience at companies such as Amazon, Deliveroo, Tesco, Stuart, and Just Eat. If you\'re ready to help build the world\'s most customer-focused company, get in touch.

Leadership Principles

These five principles describe what great looks like at Zapp. They are the single framework we use across performance reviews, growth conversations, and leadership expectations

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

We are an AI-first company

We don\'t just build software. We build intelligent systems. From AI-assisted development workflows to LLM-powered product features, we expect every engineer to embrace and actively shape how AI changes what we ship and how we ship it. If you\'re the kind of engineer who gets excited by what\'s possible when agents, models, and great product sense meet, you\'ll feel at home here.

The Role

Join Zapp and take full lifecycle ownership of the apps our customers use every day. We\'re building a world-class experience across iOS, Android, and web, and you\'ll help us get there.

Quick commerce moves fast and lives in the real world. AI is changing how we build it. That\'s the part we love. We need engineers who are curious, energetic, and thrive at the front line of both.

What you\'ll do

• Build a world-class customer experience. Develop the mobile and web experiences our customers use every day, in React Native and Expo across iOS, Android, and web.
• Bring AI into how we build. Use AI in your daily work. Share patterns that help the team move faster, and learn from what others discover.
• Help shape AI in our product. AI features in our app are still early. Spot the customer moments where AI can create magic, prototype them, and bring them to life.
• Own delivery end-to-end. Pick up a problem, design the solution, ship the mobile work, write the backend code when the feature requires it, and see it through to production.
• Own on-call. Be on the rotation, and stand behind what you ship in production.
• Keep the app fast and trusted. Profile performance, harden release processes, and protect production health.
• Raise the bar for the team. Contribute to architectural discussions and the patterns that shape our codebase. Lift the people around you.

You\'re a great fit if you

• Mobile experience. 5+ years building production software.
• Deep React Native and Expo. Strong across iOS and Android, with B2C apps in your track record.
• Strong fundamentals. Confident and idiomatic in TypeScript.
• Use AI daily. AI assistants are part of how you build. You bring back patterns that help others get more out of them too.
• Think product, not just code. You measure your work by what changed for the customer, not the lines of code shipped.
• Production minded. Solid grasp of mobile performance, app stability, release processes, and mobile security.
• Care about craft. Design systems, attention to detail, and how the product feels.
• 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.
• Passionate about execution. Curiosity, energy, and a habit of moving things forward.
• Excellent communicator. Clear in how you write and speak, and you love sharing what you learn.
• If most of these land for you, please apply. We hire on trajectory and curiosity as much as CV.

Even better if you know

• NestJS. Our backend is a NestJS service, and you\'d feel at home when features need backend work.
• GraphQL. We run a federated gateway across multiple subgraphs, so federation experience makes schema and subgraph work easier.
• GCP and DevOps. Firestore, Pub/Sub, Cloud Run, Firebase.
• Native iOS or Android. Swift or Kotlin. We maintain a custom Expo native module for iOS Live Activities, which powers order tracking on the lock screen and Dynamic Island.
• React Native Web. Cross-platform delivery from a shared codebase.
• Quick commerce or similar domain. Logistics, on-demand delivery, or another real-time, high-throughput customer-facing environment.

You won\'t be a great fit if you

• Need a fully defined process and a large, structured team to do your best work.
• Chase technical perfection at the expense of what the customer actually needs.
• Stall when the path forward isn\'t clear, or wait to be told what to do.
• Want to stay strictly inside your specialty and avoid unfamiliar parts 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.

1. 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.
2. Stage 2 - Technical interview (90 min). Live coding with 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.
3. Stage 3 - On-site interview (2 hours, in person). A visit to our office: one hour of mobile architecture, and one hour with senior leadership on how you work, what you care about, and how you align with our Leadership Principles.
4. Stage 4 - Offer.

We verify your right to work in the UK and complete reference checks before the contract.

Equity package, depending on experience.

25 days of holiday per year, plus all bank holidays.

Private health insurance.

Extended sick pay and maternity or paternity leave.