Mobile and Backend Software Engineer - Banking

We're Capital on Tap began because small businesses were underserved. Big banks were slow, their products weren't fit for purpose, and small business owners often couldn't access what they needed. We set out to fix that.

Today we're a financial platform – not just a credit card company. We offer a best‑in‑class business credit card, SME‑focused spend management platform, a savings product that hit £1 billion in funds within its first year, and a growing suite of tools and financial products that make running a small business easier.

1,000+ employees; £20bn in annual card spend; 200,000+ customers; 17,000+ Trustpilot reviews averaging 4.7 stars; and we're profitable. We’ve done a pretty good job so far, but we’re just getting started!

Hybrid role: the team works from our London offices 2 days per week.

The Banking and Repayments teams sit at the heart of Capital on Tap's product, owning the core account experience for thousands of small business customers. Banking manages account operations, transaction life cycles, balance management, Clear Bank integration, and savings. Repayments owns the repayment rails, including the most recent open banking repayments.

We value engineers who take genuine ownership, work autonomously, and bring depth across the stack. This is a high‑priority hire with real impact from day one.

• Design and build robust, scalable back-end services in C#/.NET
• Own the full SDLC – from feature inception through to production, monitoring, and continuous improvement
• Contribute to mobile development across iOS and Android using Flutter, Kotlin, and/or Swift
• Collaborate with Product, Design, and QA from early feature shaping through to delivery
• Write thorough unit and integration tests and uphold high engineering standards
• Identify bottlenecks and drive improvements across the team
• Work cross‑functionally, bridging technical decisions with business goals

• Mobile development experience in Flutter/Dart, Kotlin, or Swift – this is a firm requirement
• Strong back-end engineering experience, ideally in C#/.NET
• Solid testing practice across unit and integration testing
• Experience with CI/CD platforms such as Code Magic or similar
• Comfortable working in Agile environments
• Autonomous and collaborative – you take ownership and see things through

• Backend: C#, .NET, .NET Core
• Mobile:
  Flutter, Dart, Riverpod, GoRouter, Kotlin, Swift
• Databases: SQL Server, MongoDB, Firestore
• Cloud: GCP (Firebase) and Azure
• CI/CD:
  Code Magic

We welcome, consider and encourage applications from anyone who shares our commitment to inclusivity. Join us in creating a space where authenticity thrives, and everyone can do their best work.

• Private Healthcare including dental and opticians services through Vitality
• Worldwide travel insurance through Vitality
• Anniversary Rewards (£250, £500, £750, 4-week fully paid sabbatical)
• Salary Sacrifice Pension Scheme up to 7% match
• Octopus EV Salary Sacrifice Scheme
• 28 days holiday (plus bank holidays)
• Annual Learning and Wellbeing Budget
• Enhanced Parental Leave
• Cycle to Work Scheme
• Season Ticket Loan
• 6 free therapy sessions per year
• Dog Friendly Offices
• Free drinks and snacks in our offices

Check out more of our benefits, values and mission.