Senior Full-Stack Engineer - Credit Cards

Description

Hybrid role based in London, United Kingdom.

You will build features for the company's business credit card and take each one from the first line of code to a customer's first spend.

The company offers fast, flexible finance to small businesses, including loans and, since its 2026 launch, a business credit card.

The company has provided more than £5 billion in funding to 100,000 businesses.

The Credit Cards team builds the sign-up, card activation and management experience on the web and in the mobile app. Engineers work alongside product and design.

The team values independent thinking, challenging untested assumptions and decisions based on evidence.

Responsibilities

• Mostly backend work, plus building the frontend for your own features.
• Own features end to end: help set priorities from customer needs, then decide the data model, API, testing, release and monitoring.
• Your work is used whenever a business owner checks cashback, sets spend controls or freezes a lost card. Releases are frequent, so changes reach users quickly.
• Write Python and FastAPI services on PostgreSQL, and React and TypeScript for the web. Also work in React Native on the mobile app and on the internal CRM used by operations staff, when needed.
• Learn how card transactions flow from the card processor to the card scheme, working with the engineers who build the payments platform.
• Build with AI coding tools as a normal part of the job. For example, the mobile team writes and reviews a spec for each feature before building it with Claude Code.

Requirements

• Essential: Backend. You have built well-tested Python services for customer-facing products and kept them reliable once people depended on them.
• Essential: Data and APIs. You have designed relational data models, ideally in PostgreSQL, and built and integrated APIs.
• Essential: Frontend. You have written enough React and TypeScript to ship customer-facing features.
• Essential: Ownership. You have taken features from idea to production and owned them after launch. You have challenged plans that missed a customer need and proposed a better one.
• Essential: AI. You have built agentic workflows or used AI to extend your engineering output, at work or in personal projects. You judge when to use it, and you check its output before it reaches production.
• Essential: Communication. You write and speak clearly, directly and concisely, and adjust technical detail to your audience.
• Bonus: Mobile. You have developed iOS or Android app features, ideally in React Native.
• Bonus: Fintech. You have worked on financial products, especially card payments.
• Bonus: FastAPI. You have built and run production services with FastAPI.
• Bonus: Internal tools. You have written software for operations or support staff.

Conditions

Hybrid working, based in London, United Kingdom.

Offices in London, Leeds, Berlin and Frankfurt.

Flexible working hours.

Salary is expected to be £80,000 to £90,000. You can include your salary goals in your application.

Pay is benchmarked against market rates, with quarterly performance and salary reviews.

Benefits

• Medical insurance through Vitality, including discounted gym membership.
• A private GP service, separate from Vitality, for you, your partner and your dependents.
• 25 days of holiday a year, plus an extra day off on your birthday.
• The option to buy or sell 5 days of annual leave.
• Unlimited unpaid leave.
• A fully paid 1-month sabbatical after 4 years.
• Instant access to external counselling and therapy sessions for 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.
• Electric car scheme and cycle to work scheme.
• 2 company retreats a year, so far in France, Italy, Spain and further afield.
• A learning and development budget for everyone.
• Company-wide talks with internal and external speakers.
• Access to learning platforms such as Treehouse.
• Drinks and snacks in the offices, plus running groups, padel, and monthly ping-pong and pool competitions.