Senior Software Engineer, Supply

About Heidi Heidi was born to make it easy for more and more people to discover the power of the mountains. We burst onto the ski holiday market in 2018 (formally known as Ski Zoom) and have seen exponential growth. The company came from a desire to fix the lack of flexibility in the winter ski market. We help skiers and mountain lovers discover resorts that are hidden gems alongside the classics, and our clever tech is helping them to do it in a way that suits them best. We’re a youthful, challenger brand, with an awesome culture, and we’re shaking up a very traditional ski/mountain holiday industry. Looking to the future, we have huge ambitions for growth. We have grown year on year and expect 2026 to be our biggest yet. In that time we came 63rd in the Times top 100 fastest growing UK companies, securing £5.6 million investment and just had our most successful season ever in which we were able to hit profitability . Key to that is also growing the Heidi team with even more brilliant people than we have now. So we are looking for someone who will be fundamental to the success of our vision and is excited to help us drive that forward. Our Supply Team You'll be joining a team of four, reporting to our Senior Developer and Team Lead. Our Head of Product leads product direction, and you'll work alongside another developer. It's a tight group where everyone has real influence on what gets built and how. Why this role is interesting You'll see the direct impact of your work. A supplier integration you build means new holidays appear on the siteThe problem space is genuinely varied: one week you might be integrating a new accommodation API, the next you're solving a data mapping challenge for flight availabilityYou'll be part of a small, close team (4 people) where your contribution is visible and mattersHeidi is growing fast. We're a challenger brand shaking up a traditional industry, and supply breadth is one of our biggest competitive levers What a week might look like Monday you're debugging a data mapping issue where a supplier changed their availability format without telling anyone. Tuesday and Wednesday you're building out the API integration for a new transfer company. Thursday you're pairing with a teammate on the mix-and-match transfers project. Friday you're deploying your transfer integration to staging and writing up what you learned about the supplier's quirks for the team. What you'll be responsible for This isn't a task list. It's what you'll own and be accountable for: Supplier integrations: Building and maintaining the connections between Heidi and our suppliers. You'll work with third-party APIs, handle data mapping, error handling, and monitoring.Data quality: The data flowing through your integrations feeds our pricing engine and search platform. When it's wrong, customers see wrong prices or missing availability. You'll care about getting this right.Supply breadth projects: Contributing to the team's work on expanding what Heidi can offer: mix-and-match transfers, open jaw flights, and more flexible accommodation options.Your own growth: Whether you're stepping up from mid-level or bringing senior experience, we expect you to develop strong views on how the supply systems should evolve and to take on increasingly complex work over time. What you bring Here's what actually matters for this role: You can build and maintain backend services in C# / .NET Core. Whether you're a few years in or deeply experienced, you need to be comfortable working in this stack day-to-day.You understand relational databases (we use MySQL and SQL Server) and can write queries that perform well, not just queries that work.You've worked with third-party APIs before. You know that documentation lies, error handling matters, and retry logic isn't optional.You can work through ambiguity. Supply integrations rarely come with a clean spec. You'll need to read API docs, ask good questions, and figure things out.You communicate clearly with non-technical people. The Supply team works closely with our Head of Product and the wider business.Bonus if you have experience with Docker, cloud infrastructure (Azure), or frontend work with React/Next.js, but none of these are required. How big is the team? Engineering: 1x CTO 1x Lead engineer 2x Senior software engineers 4x Software engineers 1x Senior data engineer Product: 1x Head of product 1x Senior product manager 1x Product manager 1x Design lead 1x Senior product designer Who's going to be your manager? You’ll be reporting to JP Our tech lead. The interview process Screening call (30 mins) with our TA LeadCompetency interview (45 mins) where you show us your experience through real examplesTechnical interview (2 hrs) where we pair program and do a system design taskValues interview (45 mins) with one of our co-founders Our employee benefits Salary of £75- £100K based on experience25 days annual leave + bank holidays + 4 “me/wellbeing” daysWe have a hybrid working policy and are happy for people to balance their working week between the office and home.Vitality health insurance.Enhanced parental leave for primary /secondary carers and adoptive parents. Additional employee perks £1,000 Heidi holiday credit + additional holiday discounts.A fun packed company social calendar including our summer party, end of term conference and budget for team celebrations£300 work from home budget Our Commitment to inclusive hiring We want to create an inclusive environment that celebrates the diversity of our people whilst enabling them to do the best work of their careers. We are committed to ensuring that all our people processes are equitable. All applicants will be considered for employment without attention to age, sex, ethnicity, religion, sexual orientation, gender identity, family or parental status,national origin, veteran, neurodiversity status or disability status