Senior Full-Stack Engineer - Credit Cards

Hybrid in London, United Kingdom

We’re looking for a Senior Full-Stack Engineer.

You’ll build features on iwoca’s business credit card and own each one from the first line of code to the moment a customer makes their first spend.

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 £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 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.

The role

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.

The requirements

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.

Bonus:

• 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.

The salary

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 culture

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

We put a lot of effort into making iwoca a great place to work:

• 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.

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)