Backend Developer (C# / SQL Server)

At 433, we build platforms for millions of football fans worldwide. Every day, our systems process large amounts of data, content, and traffic related to matches, teams, players, competitions, and live football moments. That’s why we’re looking for a Backend Developer who not only writes code, but also understands what happens when large numbers of users want to access the same data at the same time. Do you have an affinity with football and do you get energy from writing code? We are looking for a Backend Developer to strengthen our team. About Us Born from a deep passion for the beautiful game, 433 represents global football culture at its core. With more than 80 million followers worldwide, including many of the sport’s greatest players, we are the largest online football platform in the world. Through close relationships with players, clubs, and leagues, we operate inside the locker room, capturing moments fans never had access to before. Behind the visible front-end is a technical environment where speed, reliability, and scalability are essential. About The Role We have an exciting opportunity for a Backend Developer to join our Tech team. In this role, you will work on the backend of our football platforms and internal systems. This includes APIs, data models, performance optimizations, integrations, and content platforms built around football data and media. Key Responsibilities Developing backend functionality in C# / .NETBuilding and optimizing APIsWorking with SQL Server and complex queriesAnalyzing and improving performanceContributing ideas around caching, scalability, and reliabilityDeveloping within and around UmbracoCollaborating with frontend developers, content teams, and product ownersBuilding systems that must continue to perform during major football moments What We’re Looking For We’re looking for someone who enjoys understanding how systems truly behave in production. Someone who doesn’t just check whether something works, but also whether it is fast, stable, and maintainable. You have experience with: C# / .NETSQL ServerREST APIsPerformance analysis and optimizationData modeling and query tuningUmbraco or similar CMS platformsGit and modern development workflows Experience: Experience with Azure, caching, observability, Application Insights, or high-traffic platforms is a plus.Experience with: Segment, Airship and Branch.io is a plus. Who You Are: As a Backend Developer at 433, you are: Goal-oriented, determined, and passionate about social media.Enjoy football, or at least understand that timing is everything in football.Comfortable in a dynamic and ambitious scale-up environment.Educated to a HBO level in a Software Engineering, Informatica, or Computer Science field.Experienced, with 3+ years as a Developer. Fluent in English, with excellent communication skills, Dutch is a plus. Able to manage internal and external stakeholders at various levels.An innovative and proactive team player.Prefer measuring over guessing.Take performance seriously.Don’t see SQL as an afterthought.Like clear and practical solutions.Understand that “it works on my machine” is not the finish line.Get energy from systems that continue to perform under pressure.Lives in the Amsterdam area and can come to the office 2-3 times a week. What’s in It for You? We are committed to creating an environment where everyone can thrive. To support this, we offer: The opportunity to work on products with a large international audience.A technical environment where performance truly matters.Plenty of room for your own ideas and input.Short communication lines between product, content, and tech.A down-to-earth team with a passion for football and quality software.Challenging technical problems around data, scalability, and speed.A competitive salary and benefits, including a pension plan and stretched vacation days.A young, ambitious team in a dynamic work environment.An office with a lot of sport activities; like Padel, a gym or you can challenge colleagues to ping-pong. Daily catered lunch at the office. Apply Now! Would you like to work on backend software used by millions of football fans? Follow the link below to apply. Send us your application, GitHub profile, LinkedIn, or simply a short explanation of why this role suits you. We’re not looking for buzzword bingo. We’re looking for someone who builds great software.