Full Stack Developer
Department: IT
Employment Type: Full Time
Location: London
Reporting To: Angus Beaumont
Description
Harmony is on a mission to be the best life safety partner to work with and for. Rated an ‘Outstanding Employer’ by Best Companies in 2025, we are only getting bigger and stronger — and we’re looking for A-players to help us get there.
We are passionate about making a difference and obsessed with quality. Our goal is to build a world where every resident can sleep safely at night, knowing their home is 100% safe.
We are looking for a Full Stack Developer to join our IT team in London, building and maintaining the internal tools, integrations, and custom platforms that power how Harmony operates. This is not a generic software role — you will be working at the heart of a fast moving business, turning real operational problems into working software, and shipping things that make a genuine difference to our teams every day.
We use Claude as our primary AI platform and have built a growing library of Claude skills, agents, and MCP integrations across the business. You will work alongside our AI Enablement Lead to build more ambitious tools — connecting our platforms, automating workflows, and developing the internal software that gives Harmony a real operational edge.
We are passionate about making a difference and obsessed with quality. Our goal is to build a world where every resident can sleep safely at night, knowing their home is 100% safe.
We are looking for a Full Stack Developer to join our IT team in London, building and maintaining the internal tools, integrations, and custom platforms that power how Harmony operates. This is not a generic software role — you will be working at the heart of a fast moving business, turning real operational problems into working software, and shipping things that make a genuine difference to our teams every day.
We use Claude as our primary AI platform and have built a growing library of Claude skills, agents, and MCP integrations across the business. You will work alongside our AI Enablement Lead to build more ambitious tools — connecting our platforms, automating workflows, and developing the internal software that gives Harmony a real operational edge.
Key Responsibilities
- Design, build, and maintain internal web applications and tools that support Harmony’s operations across estimating, pre-construction, delivery, service, and HR.
- Develop and maintain integrations between Harmony’s core platforms — including Salesforce, SimPRO, Microsoft 365, and Fabric — using APIs and MCP connectors.
- Work alongside the AI Enablement Lead to build more technically ambitious Claude skills, custom agents, and AI-powered internal tools.
- Own the full development lifecycle for your work — from requirements gathering and design through to deployment, testing, and iteration.
- Manage and maintain Harmony’s internal development infrastructure, version control, and deployment pipelines.
- Collaborate with stakeholders across the business to understand operational needs and translate them into clear, maintainable software.
- Maintain documentation for all systems, integrations, and codebases you own.
- Identify and resolve bugs, performance issues, and security vulnerabilities across Harmony’s internal tech stack.
- Stay current with relevant technologies and bring ideas that help Harmony’s internal platforms evolve.
Skills, Knowledge & Expertise
- An A-player mindset — high standards, extreme ownership and the drive to do things properly, the first time.
- Proven full stack development experience — comfortable across both frontend and backend, with production-grade code in your portfolio.
- Strong proficiency in modern web technologies — React or similar frontend framework, Node.js or Python backend, REST APIs.
- Experience building and consuming APIs and integrations — including webhooks, OAuth, and third-party platform connectors.
- Familiarity with cloud infrastructure and deployment — AWS, Azure, or GCP; CI/CD pipelines; containerisation.
- Experience working with databases — relational (PostgreSQL, MySQL) and/or document stores.
- Strong understanding of security best practices in web application development.
- Comfortable working in a fast-moving environment where priorities can shift and you own your work end to end.
- London office-based and available full time.
Nice to Have
- Experience with the Anthropic Claude API, MCP (Model Context Protocol), or building AI-powered internal tools.
- Familiarity with Salesforce, SimPRO, or Microsoft 365 APIs.
- Experience with Supabase, Cloudflare, or similar modern infrastructure tools.
- Background in construction, fire safety, or a field-service business context.
Job Benefits
This is a chance to be the developer who builds the internal tools that run one of the UK’s fastest-growing fire safety specialists — shipping real software that makes a real difference to the teams delivering life-safety work every day. At Harmony, we ask a lot — and we give a lot back. The hours are real, the standards are high and the work is demanding, but for those who show up, deliver and go the extra mile, the rewards follow. A-players here enjoy a competitive salary, a Personal Development Plan with ongoing training and mentoring, unlimited holiday, a bonus scheme paying up to 50% of annual salary, enhanced maternity and paternity, lunch, snacks and refreshments on us every day (fresh fruit and Takeaway Friday included), a team social budget, cycle to work, an auto-enrolment pension, two major company events a year and our Reward and Recognition scheme — including European mini breaks for those who go above and beyond. It is a collaborative, high-energy environment focused on doing things the right way — and none of it is a perk for showing up; it’s what we share with the people pulling the business forward.
Harmony is an equal opportunity employer. We consider all applicants for employment regardless of age, disability, sexual orientation, gender identity, family or parental status, race, colour, nationality, ethnic or national origin, religion or belief. We want everyone who works with us to feel valued and to make a difference.
Harmony is an equal opportunity employer. We consider all applicants for employment regardless of age, disability, sexual orientation, gender identity, family or parental status, race, colour, nationality, ethnic or national origin, religion or belief. We want everyone who works with us to feel valued and to make a difference.
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