About this role.
Capital on Tap is hiring a full-stack Software Engineer to help build credit-card and payment products for small businesses. The engineer will develop scalable C#/.NET services and responsive React interfaces, owning work from implementation through production monitoring and improvement. The role requires at least three years of experience with C#, .NET Core, SQL Server, testing practices, databases, and Agile delivery. It begins fully remote and will transition to a hybrid arrangement with two days per week at the Lisbon office. The position is part of a growing fintech engineering team and emphasizes empowered technical decision-making, collaboration, and continuous learning.
Role DNA
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Job Complexity
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4/5Autonomy Level
4/5Communication Load
4/5Salary analysis
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Core skills
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Sample interview questions
I would start by clarifying the workflow, volume, consistency requirements, failure modes, and security constraints. I would separate domain logic from transport and persistence concerns, use idempotency keys for payment actions, implement robust validation and observability, and protect sensitive data. I would also define integration and contract tests for critical paths before production rollout.
I use unit tests for isolated business rules, edge cases, and error handling, keeping external dependencies mocked or abstracted. I use integration tests for database access, API endpoints, authentication, and critical service interactions. For user-facing flows, I ensure important behavior is covered at an appropriate level and keep the test suite reliable enough to run in CI.
I prioritize clarity, accessibility, responsive behavior, and accurate presentation of financial data. I manage loading, error, and empty states explicitly, validate user inputs carefully, and avoid exposing sensitive information in the client. I also use reusable components and predictable state management so the interface remains maintainable as features expand.
I would first assess impact, use logs, metrics, traces, and recent deployment history to narrow the cause, and communicate status to relevant stakeholders. I would mitigate user impact safely, validate the fix through monitoring, and document the root cause. Afterwards, I would add tests, alerts, or process changes to reduce the chance of recurrence.
I frame options around user impact, delivery time, reliability, risk, and long-term maintenance rather than implementation details alone. I provide a clear recommendation, explain assumptions and consequences, and invite questions to ensure alignment. This helps stakeholders make informed decisions while preserving technical quality.
We’re Capital on Tap 👋
💳 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’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!
We opened our first Portuguese office in Porto in autumn 2025, and in less than a year it has grown to a team of 50. Lisbon is the next step. We’re opening our first office in the city and looking for engineers to join as founding members of the team, helping shape how we build, hire and work here from day one.
🏡🏢 The role starts out fully remote. Once our Lisbon office is open, it will move to a hybrid set-up of two days a week on site.
Salary: €40,000-55,000
This is a multiple-headcount role, so please don’t be put off if you’ve seen it advertised for a while.
What You’ll Be Doing
We’re looking for Full stack Engineers to help us build the best credit card and payment products for small businesses. If you’re looking for an environment where you’re given the freedom to make empowered decisions, research new technologies, and learn/share knowledge with your peers. Then keep on reading!
- You’ll build robust and scalable solutions using .Net technology
- From the first line of code to production, monitoring, and continuous improvement – you’ll own the SDLC
- You’ll craft slick, responsive user interfaces with modern JavaScript frameworks (React), making sure our products don’t just work, they feel great to use
- Teamwork makes the dream work – you’ll partner with Product Managers, QA’s, and fellow Software Engineers
- You’ll build bulletproof unit and integration tests to keep our software sharp and our users happy
- Bugs happen. When they do, you’ll be ready to troubleshoot and tweak as needed
- You’ll bridge the gap between tech speak and business goals, ensuring everyone’s on the same page and moving forward together
We’re Looking For 🔎
Required skills:
- A minimum of 3+ years hands-on experience in C#, .Net Core, SQL Server, ideally JavaScript and React also!
- Good testing practices, in both Unit and Integration testing
- Good understanding of database technologies
- Experience in using Agile development practices
- A passion for learning new skills and technologies
- A proactive, supportive, and collaborative team player
Our Tech Stack
- Backend: C#, .Net, .Net Core
- Frontend: React, JavaScript
- Mobile: Flutter, Dart
- Databases: SQL Server, MongoDB
- Cloud: Azure & GCP
Interview Process 🤝
- First stage: 30-minute intro, CV review, and values with a Talent Partner
- Second stage: 45-minute “Tech Chat” with a Team Manager
- Final stage: 90-minute Code Pairing + 30-minute Values Interview
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
Check out our benefits:
🏥 Private Healthcare through AdvanceCare
🎁 Anniversary Rewards (€280, €570, €860, 4-week fully paid sabbatical)
🏖️ 36 days holiday (inclusive of public holidays with public holidays carried over if they fall on a weekend)
📖 Annual Learning and Wellbeing Budget
💬 6 free therapy sessions per year
🍫 Free drinks and snacks in our offices
Other Info
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✔️Keep updated on new job opportunities by following us on Linkedin.
📧Email careers@capitalontap.com if you have any questions.
Excited to work here? Apply!
If you’d like to progress your career within our fast growing, profitable fintech then click apply and we will aim to get back to you within 3 working days (during busy periods this could take up to 5 working days.)
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