Senior Product Engineer (Scala, 3-Month Contract)

About the role

Yonder, a fintech company behind a debit and credit rewards card, is looking for an experienced Senior Product Engineer on a 3-month contract to add delivery capacity to its engineering team. The work is primarily Scala backend, but contributors are encouraged to help with infrastructure, the React Native mobile app or the Next.js webapp. The team is small and owns the full end-to-end cycle, from development lifecycle and system architecture to infrastructure.

The contract starts as soon as possible, is outside IR35 and is based in Brick Lane, London. The rate is £600-£650 per day.

Key responsibilities

• Deliver features and improvements across Scala microservices covering 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 the React Native mobile app.
• Leave things better than you found them, with clear documentation and handover.

Required profile

• Deep, production Scala experience, ideally on the Typelevel stack (Cats Effect, Http4s, fs2).
• Understanding of distributed systems, microservices, RESTful APIs and Kafka or similar event-driven architectures.
• Ability to ramp up quickly and deliver within the first couple of weeks.
• Bonus: React Native experience, fintech or payments experience, and good use of AI coding tools.
• Not a fit if you need a long onboarding, want to stay in one narrow part of the stack, or chase perfection over value in a fixed engagement.

Required skills

• Scala (Typelevel ecosystem)
• Kafka
• React Native and Next.js (bonus)
• Automated testing

What we offer

• Office-first, remote-friendly setup: at least 3 days a week in the Shoreditch office, with everyone coming in on Mondays.
• A values-led approach and a fast process: a 30-minute intro call with the CTO, then a 90-minute technical interview with a system design exercise, with a decision within 24 hours.
• Right to work, criminal record, politically exposed person and credit default checks completed before the engagement starts.