Senior Back-End Engineer - Ledger Platform

Senior Back-End Engineer - Ledger Platform Hybrid in London (UK) or Remote within the UK We’re looking for a Senior Back-End Engineer This role is a chance to tackle complex, high-impact challenges at the heart of our fintech platform. You will join the team that owns iwoca's ledger — the system of record for the money we lend and collect — and you will be responsible for scaling it across the full lifecycle of our credit card and lending products, building the reconciliation and reporting that prove it correct, and laying the foundations for our next generation of products. This is a hands-on role: you'll design these systems, write the code, and own them in production. The company Small businesses move fast. Opportunities often don’t wait, and cash flow pressures can appear overnight. To keep going, and growing, SMEs need finance that’s as flexible and responsive as they are. That's why we built iwoca. Our smart technology, data science and five-star customer service ensures business owners can act with the speed, confidence and control they need, exactly when it's needed. We’ve already cleared the way for 100,000 businesses with more than £4 billion in funding. Our passionate team is driven to help even more SMEs succeed, through access to better finance and other services that make running a business easier. Our ultimate mission is to support one million SMEs in their defining moments, creating lasting impact for the communities and economies they drive. The team The Ledger Platform team owns the ledger across all of iwoca's products, from credit cards to our lending range, plus everything around it: reconciliation, financial reporting, and the data Finance, Accounting and Capital Markets run on. We work closely with a Product Manager, shipping frequently and owning our systems in production. Some of the team work fully remotely and others are hybrid, working 1-3 days per week in the London office.

The role

Responsibility and Autonomy: Lead the delivery of projects involving many stakeholders and systems. Go beyond the code to develop deep expertise in our domain — our core financial products and our stakeholders' needs — and become a trusted technical advisor to the business. Perform detailed technical scoping and prototyping to support feasibility testing and decision making. Delivery and Collaboration Architect and implement scalable solutions for complex challenges: the lifecycle of an account, interest and repayment allocation, reconciliation, and how financial data reaches our reporting stack. Use domain modelling to find the simple design behind a complicated problem, and structure software so that it is easy to understand, test and evolve. Be pragmatic about which parts of a problem actually need solving now. The hardest work here is deciding what not to build. Build solutions that avoid single points of failure, and make sure our releases happen with zero downtime. Translate ambiguous product requirements into clear, actionable technical plans that guide the team's work. Promptly investigate and fix live issues, and ensure they do not resurface. Own what you ship in production and keep it reliable and easy to operate. Contribute high-quality, production-ready code and foster a collaborative environment by reviewing work and writing useful documentation. Learning and Growth: Work with the team to improve our development and agile practices and raise our engineering standards. Share new approaches and tooling with the wider engineering group through our internal forums and company-wide talks. AI: We're pushing hard on AI-assisted development. Engineers here write clear technical specs, let skills and agents implement boiler-plate, and hold a high bar on code review — the person, not the model, is accountable for what merges. We expect AI output to be validated for correctness, performance and security like any other change. We give the team unlimited tokens across all models and expect people to experiment. The requirements Essential: Extensive back-end engineering experience. Experience building and running microservices and distributed systems in production. Comfortable reasoning about durable cross-service communication, transactional correctness, and failure modes at scale. Extensive experience with relational databases, ideally PostgreSQL, but open to MySQL or similar (e.g., MS SQL, Oracle); emphasis is on data integrity. Experience with systems where correctness is a hard requirement — ledgers, accounting, billing or payments, ideally in a regulated setting — including the invariants, immutable audit trails and reconciliation controls that enforce it. Experience leading a feature or project end to end — scoping, design, delivery, and running it in production. You use AI (like Cursor, Claude Code or similar) in your daily flow - whether for work or for fun. You use it to blast through boilerplate and research, so you can focus on the hard parts: complex architecture, rigour, and high-stakes decision-making. A strong technical or mathematical foundation, evidenced by a degree in a quantitative field (Computer Science, Engineering, Physics, Maths or similar) or equivalent professional experience. You work well as a peer: pairing on hard problems, giving useful code review, and unblocking teammates day-to-day. Clear written and verbal communication — you can explain a technical trade-off to Finance, and a business constraint back to engineers. Bonus: A background in high-logic or high-scale fields like Fintech, Gaming, Healthcare Tech, Logistics, Security/Cryptography or similar. Working knowledge of modern data tooling - ideally Snowflake and dbt - used to build analytical or reporting pipelines. Knowledge of messaging frameworks and event-driven patterns (e.g. Kafka). The salary We expect to pay from £80,000 to £110,000 for this role. But, we’re open-minded, so definitely include your salary goals with your application. We routinely benchmark salaries against market rates,