Full-Stack Engineer - Credit Cards

iwoca; City of Westminster; On-site; GBP 80,000 - 90,000; Full time

Benefits offered by this job

Flexible working hours

Medical insurance

3% Pension contributions

Employee equity incentive scheme

25 days holiday + extras

Job summary

iwoca is seeking a senior full-stack engineer who will primarily work on the backend while also delivering frontend for features. You’ll own features end-to-end, from data modelling and APIs to testing, release, and monitoring, shaping the product based on customer needs.

Expect to ship frequently, with impacts across cashback controls and card-related workflows. You’ll write Python and FastAPI services backed by PostgreSQL, and frontend in React/TypeScript, with React Native on the iwoca Mobile

Qualifications

• Backend engineering: well-tested Python services for customer-facing products.
• Data models and APIs: relational data models, ideally PostgreSQL, with APIs.
• Frontend: React and TypeScript for customer features.
• Product ownership: own features from idea to production and live metrics.
• AI leverage: build agentic workflows and use AI to scale output; review results before production.
• Communication: clear, concise communication tailored to audience.

Responsibilities

• Shape team roadmap from customer needs and decide feature implementation.
• Design data models and APIs and implement backend services in Python.
• Develop frontend features in React and TypeScript for customer-facing experiences.
• Own features end-to-end from conception to production and monitoring.
• Apply AI tools to scale engineering output and validate results before release.
• Communicate technical details clearly to stakeholders.

Skills

Backend engineering

Python

PostgreSQL

APIs

Frontend

React

TypeScript

Product ownership

AI leverage

Communication

Tools

FastAPI

React Native

Claude Code

Job description

As a senior full-stack engineer, you'll work mostly on the backend, and build the frontend for your features too.

• Ownership. You'll shape what the team builds next, starting from what customers need. You'll decide how each of your features works, from the data model and API to how you test, release, and monitor it.
• Impact. Business owners use your work every time they check their cashback, set spend controls, or freeze a lost card. The team releases often, and your changes reach them quickly.
• Variation. You'll write Python and FastAPI services backed by PostgreSQL, and React and TypeScript for the web. You'll also work in React Native on the iwoca Mobile App, and on the Credit Cards CRM that operations staff use, when a feature needs it.
• Card expertise. You'll learn how card transactions work - from the card processor to the card scheme - alongside the engineers who build iwoca's payments platform.
• AI-first engineering. You'll build with AI coding tools as standard. On the iwoca Mobile App, for example, the team writes a spec for each feature and reviews it before building it with Claude Code., Mobile. You've developed iOS or Android app features, ideally in React Native.
• Fintech. You've worked on financial products, especially card payments.
• FastAPI. You've built and run production services with FastAPI.
• Internal tools. You've written software for operations or support staff.

Essential:

• Backend engineering. You've built well-tested Python services for customer-facing products, and kept them working once people relied on them.
• Data models and APIs. You've designed relational data models, ideally in PostgreSQL, and built and integrated APIs.
• Frontend. You've written enough React and TypeScript to build and ship customer-facing features.
• Product ownership. You've taken features from an idea to production and owned them once they were live. You've challenged a plan when it didn't meet a customer need, and offered a better one.
• AI leverage. You've built agentic workflows, or used AI to scale your engineering output beyond what you could deliver alone, at work or in your own projects. You judge when to use it and when not to, and you check its output before it reaches production.
• Communication. You write and speak clearly, directly, and concisely. You adapt technical detail to your audience.

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 £5 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 iwoca launched its business credit card in 2026. It gives small businesses a fast, flexible way to pay for what they need and control their cash flow, alongside iwoca's loans. The credit card is a core part of iwoca's long-term growth. The Credit Cards team builds what business owners use to sign up, get their card, and manage it, on the web and in the iwoca Mobile App. It's cross-functional - engineers collaborate with product and design. At iwoca, the best idea wins.

We model our culture on independent thinking, challenging untested logic, and evidence-based decisions. We prioritise learning and growth, and give people the autonomy to develop in the direction that makes them most effective. We're a tech company and believe in the power of AI to help us work faster and better. We provide the infrastructure where every iwocan always has access to the best models and where those models have access to all of our data. We will help our people to learn how to use and grow with the new tools available to them.

The offices

• Offices in London, Leeds, Berlin, and Frankfurt with plenty of drinks and snacks.
• Events and community-led groups, including running groups, padel, and monthly ping-pong and pool competitions.

We expect to pay from £80,000 to £90,000 for this role. But, we're open-minded, so definitely include your salary goals with your application. We routinely benchmark salaries against market rates, and run quarterly performance and salary reviews.

The benefits

• Flexible working hours.
• Medical insurance from Vitality, including discounted gym membership.
• A private GP service (separate from Vitality) for you, your partner, and your dependents.
• 25 days' holiday per year, an extra day off for your birthday, the option to buy or sell an additional five days of annual leave, and unlimited unpaid leave.
• A one-month, fully paid sabbatical after four years.
• Instant access to external counselling and therapy sessions for team members that need emotional or mental health support.
• 3% Pension contributions on total earnings.
• An employee equity incentive scheme.
• Generous parental leave and a nursery tax benefit scheme to help you save money.
• Electric car scheme and cycle to work scheme.
• Two company retreats a year: we've been to France, Italy, Spain, and further afield.

And to make sure we all keep learning, we offer:

• A learning and development budget for everyone.
• Company-wide talks with internal and external speakers.
• Access to learning platforms like Treehouse.

Useful links:

• iwoca benefits & policies
• Interview welcome pack (TAP)