Mobile and Backend Software Engineer - Banking

Capital on Tap; Greater London; Hybrid; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Private Healthcare including dental

Worldwide travel insurance

Annual Learning and Wellbeing Budget

Cycle to Work Scheme

Six free therapy sessions

Dog Friendly Offices

Free drinks and snacks

Job summary

Capital on Tap is seeking a Mobile and Backend Software Engineer for its Banking platform in London. The role blends back-end services in C#/.NET with mobile contributions through Flutter, Kotlin, and Swift, within a hybrid work setup two days per week at our London office.

You'll own end-to-end delivery, collaborate across Product, Design and QA, and uphold rigorous testing standards. A high-impact, fast-moving fintech environment awaits high-ownership engineers.

Qualifications

• Mobile development experience in Flutter/Dart, Kotlin or Swift.
• Strong back-end engineering experience, ideally in C#/.NET.
• Solid testing practice across unit and integration testing.
• Experience with CI/CD platforms such as CodeMagic or similar.
• Comfortable working in Agile environments.
• Autonomous and collaborative – you take ownership and see things through.
• Database experience: SQL Server, MongoDB, Firestore.
• Cloud experience: GCP (Firebase) and Azure.
• CI/CD familiarity: CodeMagic.

Responsibilities

• 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.

Skills

Flutter/Dart

Kotlin

Swift

C#/.NET

Unit testing

CI/CD CodeMagic

Agile

SQL Server

MongoDB

Firestore

GCP

Azure

Tools

CodeMagic

Job description

Mobile and Backend Software Engineer - Banking

London

Capital on Tap started 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 are a financial platform that offers a best‑in‑class business credit card, SME‑focused spend management platform, a savings product that reached £1 billion in funds within its first year, and a growing suite of tools and financial products that make running a small business easier.

We have over 1 000 employees, £20 bn in annual card spend, more than 200 000 customers, and over 17 000 Trustpilot reviews averaging 4.7 stars. We are profitable and just getting started.

This is a hybrid role; the team works from our London offices two days per week.

The Team

The Banking and Repayments teams sit at the heart of our product, owning the core account experience for thousands of small business customers. Banking manages account operations, transaction lifecycles, balance management, ClearBank 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.

What You’ll Be Doing

• 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

What We’re Looking For

• 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 CodeMagic or similar
• Comfortable working in Agile environments
• Autonomous and collaborative – you take ownership and see things through
• Database experience: SQL Server, MongoDB, Firestore
• Cloud experience: GCP (Firebase) and Azure
• CI/CD familiarity: CodeMagic

Diversity & Inclusion

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.

Great Work Deserves Great Perks

• Private Healthcare including dental and opticians services through Vitality
• Worldwide travel insurance through Vitality
• Anniversary Rewards (£250, £500, £750 and a 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
• Six free therapy sessions per year
• Dog Friendly Offices
• Free drinks and snacks in our offices

Equality, Diversity and Inclusion

At Capital on Tap we are fully focused on equality and believe deeply in diversity of race, gender, sexual orientation, religion, ethnicity, ability, national origin and all the other characteristics that make us who we are. We want to be a place where a diverse mix of talented people wants to come and do their best work and most importantly feel included and able to be their authentic selves.