Senior Software Engineer

Capital on Tap; Warszawa; Remote; PLN 180,000 - 260,000; Full time

Job summary

Capital on Tap is seeking Senior Software Engineers to help build products used by small businesses in the UK and US. You will work across cross-functional teams, owning problems end to end from first line of code through production, monitoring and continuous improvement.

This isn’t a ticket-taker role; we want engineers who challenge approaches, ensure quality, and ship what the customer wants. Join a capable, fast-moving team with a strong impact.

Qualifications

• 5+ years of hands-on experience in C#, .NET and SQL Server.
• React and TypeScript are a strong plus.
• Strong testing practices across unit and integration testing.
• Experience working in agile, cross-functional teams.

Responsibilities

• Designing and building robust, scalable solutions in .NET/C#.
• Participating in architectural decisions and technical direction.
• Collaborating with Product and QA to align on requirements.
• Writing thorough unit and integration tests and upholding code quality.
• Communicating complex engineering decisions to stakeholders.
• Mentoring and supporting engineers to raise the team standard.

Skills

C#

.NET

SQL Server

React

TypeScript

Agile

Job description

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!

This is a remote B2B contract role.

The Role

We're looking for Senior Software Engineers to help us build the products that small businesses across the UK and US rely on every day. You'll work across cross-functional teams alongside Product Managers, QA Engineers, and fellow Software Engineers, owning problems end to end, from the first line of code through to production, monitoring, and continuous improvement.

This isn't a role for someone who wants to be handed a ticket and told what to build. We're looking for engineers who understand the problem, challenge the approach when it needs it, and take pride in the quality of what they ship. We only build what the customer wants.

What You'll Be Doing

• Designing and building robust, scalable solutions in .Net/C#, taking full ownership of the SDLC from concept through to production
• Playing an active role in architectural decisions and technical direction, shaping how things are built, not just building them
• Working closely with Product and QA, bringing your technical perspective early and often
• Writing bulletproof unit and integration tests and holding a high bar for code quality across the team
• Communicating clearly across technical and non-technical stakeholders, translating complex engineering decisions into business context
• Mentoring and supporting engineers around you, raising the standard of the team as well as your own output

We're Looking For

• 5+ years of hands-on experience in C#, .Net and SQL Server; React and Typescript are a strong plus
• A clear sense of what senior means. Not just years in the seat, but ownership, judgement, and the ability to operate with ambiguity
• Strong testing practices across unit and integration testing
• Broad engineering knowledge that goes beyond your core stack; the kind of depth and curiosity that comes from solving hard problems in complex, distributed systems
• The ability to communicate clearly and confidently, with your team, with Product, and with the wider business
• Experience working in agile, cross-functional teams
• Someone who's proactive, direct, and makes the people around them better

Our Tech Stack

• Backend: C#, .Net, .Net Core
• Frontend: React, Typescript
• 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.

Other Info

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