Senior Product Engineer (Contract, 3 Months)

Yonder; Greater London; On-site; GBP 111,000 - 120,000; Full time

Job summary

Yonder is seeking an experienced Senior Product Engineer for a 3-month contract in London. The role focuses on Scala backend work across payments, core banking and rewards, with cross-functional collaboration and occasional React Native work.

You’ll join a small team responsible for end-to-end delivery, architecture and infrastructure. You’ll need strong production Scala experience, familiarity with microservices and Kafka, and a track record of delivering quickly in time-critical environments.

Qualifications

• Deep production Scala experience, preferably with Typelevel stack (Cats Effect, Http4s)
• Experience with microservices, RESTful APIs and Kafka or similar event-driven architectures
• Ability to ramp up quickly on an existing codebase and ship production changes

Responsibilities

• Deliver features across Scala microservices including payments, core banking and rewards
• Build event-driven integrations with Kafka and external partners
• Improve reliability, performance and test coverage of services
• Contribute to React Native mobile app when needed
• Provide clear documentation and handover of deliverables

Skills

Scala

Distributed systems

React Native (bonus)

Tools

Kafka

AlloyDB

Kubernetes

Job description

What’s Yonder?

“It's as if Time Out, Amex and Monzo had a baby” - Will T, Yonder Member

Yonder combines credit and debit in one membership that’s fair, flexible and actually enjoyable. No jargon. No dusty points system. Just rewards that actually feel rewarding, from bao to beer to a boarding pass.

The engineering team sits at the heart of the company; we work in squads alongside product and design, and closely with risk, compliance, operations and partnerships.

Sounds cool. What’s my part in this?

We’re looking for an experienced Senior Product Engineer on a 3-month contract to add delivery capacity to our engineering team. The work is primarily Scala backend, but we don’t believe in rigid boundaries; everyone is encouraged to contribute wherever the problem takes them, whether that’s infrastructure, the mobile app (React Native) or the webapp (Next.js).

You’ll be working alongside a small engineering team that owns everything end to end: the development lifecycle, system architecture and the infrastructure it all runs on.

You’ll need to be productive quickly: picking up an established codebase, understanding the domain and shipping production changes within your first couple of weeks.

• Duration: 3 months, starting ASAP

• Rate: £600–£650/day

• IR35: Outside

• Location: Brick Lane

What you’ll work on

• Deliver features and improvements across our Scala microservices, spanning payments, core banking and rewards.

• Build event-driven integrations with Kafka, internal services and external partners.

• Improve the reliability, performance and test coverage of the services you work on.

• Where needed, deliver changes in our React Native mobile app.

• Leave things better than you found them, with clear documentation and handover of the work you deliver.

Our Stack

• Backend: Scala microservices on the Typelevel ecosystem (Http4s, Cats Effect)

• Data & messaging: AlloyDB and Kafka

• Infrastructure: GCP and Kubernetes

• Frontend: React Native mobile app, Next.js webapp

• AI tooling: AI coding tools are widely used and actively encouraged, including Claude Code, Cursor and Codex.

You're a great fit if you

Have deep, production Scala experience: You know functional Scala well, ideally on the Typelevel stack (Cats Effect, Http4s, fs2).

Understand distributed systems: You have strong experience with microservices, RESTful APIs and Kafka or similar event-driven architectures.

Ramp up fast: You have a track record of joining existing teams and codebases and delivering quickly.

Bring React Native experience (bonus): You can ship mobile features comfortably, even if the backend is your main strength.

Have fintech or payments experience (bonus): You’ve worked in regulated environments, card payments or banking systems.

Use AI tools well: You use AI to accelerate delivery without compromising quality.

Own quality: You treat automated testing as part of the job.

You won’t be a great fit if you

Need a long onboarding period or detailed specs before you can contribute.

Only want to work in one narrow part of the stack.

Chase technical perfection over delivering value within a fixed engagement.

What’s it like working at Yonder?

We’re office-first, remote-friendly

We’re based in our Shoreditch office, complete with dog visitors and plenty of comfortable space to do your best work. We ask you to come into the office at least 3 days a week, with everyone coming in on Mondays.

We take a values-led approach

Our principles are incredibly important to us, so we recommend you check them out here: Our DNA

Our process:

We know contractors move quickly, so we do too.

• Stage 1: Intro call (30 mins). A video call with Harry Jell, our CTO; to cover the engagement, your experience and availability.

• Stage 2: Technical interview (90 mins). A deep dive into your Scala experience and past projects, plus a system design exercise. This will be in-person at our Shoreditch office.

• Decision. We aim to give you a decision within 24 hours.

Other things to know:

• Because we’re FCA-regulated and handle sensitive customer data, we complete right to work, criminal record, politically exposed person and credit default checks before the engagement starts.