Backend Developer C# / SQL Server - 433

433 Amsterdam; Amsterdam; Hybrid; EUR 60,000 - 90,000; Full time

Benefits offered by this job

Pension plan

Stretched vacation days

Daily catered lunch

Office with sport activities

Hybrid schedule

Job summary

433 Amsterdam is seeking a Backend Developer to strengthen our Tech team in Amsterdam. You will work on the backend of football platforms and internal systems, focusing on APIs, data models, performance, integrations, and content platforms built around football data and media.

The role requires building scalable services in C# / .NET, using SQL Server, and collaborating across product and content teams to deliver fast, reliable systems. Hybrid work and football passion are valued.

Qualifications

• Experience with backend systems in a high-traffic environment.
• Strong understanding of data modeling and query tuning.
• Familiarity with CMS platforms like Umbraco and modern DevOps workflows.

Responsibilities

• Develop backend functionality in C# / .NET.
• Build and optimize APIs.
• Work with SQL Server and complex queries.
• Analyze performance and optimize bottlenecks.
• Contribute ideas on caching, scalability, reliability.
• Develop within and around Umbraco.
• Collaborate with frontend, content, and product teams.
• Ensure systems perform under major football moments.

Skills

C# / .NET

SQL Server

REST APIs

Performance optimization

Data modeling

Umbraco CMS

Git workflows

Education

Bachelor's or HBO degree in Software Engineering

Tools

Azure

Application Insights

Umbraco CMS

Git

Job description

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# / .NET
• Building and optimizing APIs
• Working with SQL Server and complex queries
• Analyzing and improving performance
• Contributing ideas around caching, scalability, and reliability
• Developing within and around Umbraco
• Collaborating with frontend developers, content teams, and product owners
• Building 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# / .NET
• SQL Server
• REST APIs
• Performance analysis and optimization
• Data modeling and query tuning
• Umbraco or similar CMS platforms
• Git 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.

We’re not looking for buzzword bingo. We’re looking for someone who builds great software.