Senior Software Engineer

About us At ZeroKey, we're on a mission to build innovative solutions that integrate technology within the UK financial advice market. Founded in December 2023, our solution quickly won Best in Show at The Lang Cat's inaugural AdviceTech Catwalk. Today, we are working with and providing critical infrastructure to some of the biggest and most exciting fintechs operating in the industry, from FTSE 250 companies to AI start-ups. We're a small, ambitious team with previous start-up and scale-up experience now looking to accelerate. If you want to join early and make a visible impact within a company that's already making headlines, this is the opportunity. The role This is a rare chance for a Senior Software Engineer to join an early-stage fintech and shape the technical foundations of a company already working with some of the biggest names in the UK financial advice market. You will own the design and delivery of the integrations that move data between systems, and take a leading hand in the API we expose so others can connect to us – the layer everything else depends on. You will work across a modern TypeScript-based stack alongside a Laravel back-end, building everything from backend services to browser extensions and front-end tooling. You will report into the Head of Software Engineering with direct access to the CEO, and you will be one of a small number of engineers whose decisions set the direction for everyone who follows. What you'll do Design, build and maintain integrations with third-party systems, and own them end to end.Shape and extend our unified API for external provider connections.Ship Node.js backend services and TypeScript browser extensions.Work with Vue.js on user-facing components.Make and document architectural decisions, and weigh the trade-offs openly with the team.Set the standard for code quality, testing and documentation, and hold the bar in review.Mentor junior engineers and help new starters become productive quickly.Work directly with partners' technical teams on integration design where it helps us move faster.Build with security and data protection in mind – we operate in a regulated, sensitive-data environment. What we're looking for A Senior Software Engineer with a minimum of 5 years' commercial experience.Strong TypeScript and JavaScript proficiency.Deep Node.js service and API experience in production, including design, versioning and support.A track record of integrating disparate systems and third-party APIs, including the awkward ones.Vue.js or other modern front-end framework experience.Sound judgement on architecture and trade-offs, and the ability to explain your reasoning to technical and non-technical people alike.Experience mentoring or leading other engineers.Self-motivated, comfortable with ambiguity, and able to take a problem from vague to shipped without being managed through it.A team player who communicates well and takes pride in their craft. Nice to have Experience with Laravel or PHP.Strong grounding in REST API design principles.Experience with cloud platforms, particularly AWS and serverless architectures.Experience in fintech, financial services or another regulated environment.Interest or experience in using AI tools to enhance development productivity (e.g. code generation, testing, MCP or automation). Why you'll love it here Be one of the first engineers at a company that is already providing infrastructure for some of the biggest fintechs in UK financial advice.Real influence over architecture and technical direction, at the point where those decisions still matter.An environment that trusts you to know what you are doing and gives you the space to do it.Real problems, real partners, real impact – your work will make a difference to how financial advisers work every day.Work directly with a founding team that has already built and scaled a fintech from start-up through to exit.