Java Developer @ Itsme

Company

Belgian Mobile ID, known for its successful app itsme®, is a Belgian scale-up and pioneer in digitalization. In 2017, Belgian Mobile ID united the seven Belgian market leaders from the banking and telecommunications sector: Belfius, BNP Paribas Fortis, KBC, ING and Orange Belgium, Proximus and Telenet. Through joint efforts, they developed itsme®, Belgium's official mobile identity. With this mobile identity app, every Belgian citizen can identify him/herself when logging into digital applications, when approving (payment) transactions and even when signing official documents. Card readers, passwords or cards with tokens are no longer required. itsme® guarantees secure identification through the combination of the itsme® app, the user’s mobile phone and the user’s unique itsme® PIN or biometric identification. itsme® is recognized as a Level of Assurance ‘High’ e-identification mean, and as a ‘qualified’ trust services provider for electronic signatures in the eIDAS regulation, which means that the app complies with the highest security levels.

The number of users of the identity app itsme® continues to rise. In one year, 700,000 itsme® accounts were added, a growth of 11%. Today, 7 million Belgians already use the itsme app to identify themselves, confirm transactions and sign documents online, and they do so remarkably often: an average of 47 actions per person per year, or almost 1 per week. Today, itsme® is already available in Belgium and 13 other European countries!

Belgian Mobile ID closed partnerships with more than 800 companies, both in public and private sectors. The government is counted as one partner in this total amount, with more than 2.000 platforms. Although itsme® is mainly used for government purposes and in the banking, insurance and telecommunications sector, the importance of the app is increasing in other sectors as well. Examples of other industries are the gaming industry (e.g. Napoleon Games), HR sector, hospitals, mobility services, …

Role

The goal of this role is very clear: it's all about diving deep into an existing Java environment. This is not a greenfield project where you're starting from scratch—this is a true brownfield setup. The codebase already exists, it's running in production, and now it's about taking over the maintenance and optimization of that system from an external team.

As a developer, you’ll be expected to really get under the hood of this monolithic application—understand how it works, what its logic is, and how it connects to the rest of the infrastructure. Around 80% of your time will be focused on maintaining the existing application, resolving bugs, supporting the run, and gradually improving performance. You won’t be responsible for building new features from the ground up, but you will be crucial in keeping the engine running smoothly.

The security of the application has already been thoroughly audited and validated, so this isn’t a high-pressure security role. The challenge lies more in stability, clarity, and maintainability. Together with the architecture team, you’ll also contribute to the long-term goal of breaking down the large monolith into modular, manageable components.

One key aspect of this role is reverse engineering— together with the current back-end team, you ’ll be looking at existing code to understand what it does and how, then translating that understanding into clear, logical components. Over time, this will allow the team to extract parts of the code and start modularizing the entire system.

So in essence, this is a role for someone who takes ownership over the “invisible engine” behind the app—the backend that powers everything and makes sure it all runs efficiently. You’re the person making sure that when users interact with the app, everything just works—seamlessly and reliably.

Offer

• You’ll be responsible for the invisible engine behind Itsme—one of the most widely used digital identity platforms in Belgium, with millions of users. Your work will directly impact performance, stability, and the experience of every end user.
• A role within one of Europe's fastest-growing scale-ups, where you can develop and grow;
• This is not a greenfield playground. You’ll be diving into a Java monolith, built and evolved over 15 years. It’s brownfield in the truest sense—complex, mature, and full of hidden corners. But that’s the point: if you thrive on reverse engineering, cleaning up legacy code, untangling logic, and turning chaos into clarity, this is exactly your kind of playground.
• You’re not just maintaining something—you’re taking the wheel. From CI/CD flows and deployment pipelines to modularisation strategy and refactoring decisions, you’re in the driver’s seat for the backend’s evolution. The goal is to internalise and truly own the run.
• Itsme is a household name. Working on its core platform is not just technically rewarding, it’s also something that carries weight on your resume.
• Flexible working arrangements, including remote work and a vibrant office in Brussels;
• You’ll join a team that values quality, fun, security, ambition and ownership.
• A fixed contract with a competitive salary package, reflecting your pivotal role in Itsme’s mission.

Profile

Background and experience

• Minimum of 4 years experience in backend development, with a focus on Java & Spring Boot;
• Strong experience with backend architecture and legacy systems, especially those needing reverse engineering, refactoring, and optimisation;
• Demonstrated experience in optimising and cleaning up a backend, particularly for brownfield project;
• Experience with CI/CD processes (e.g., Jenkins, automated builds, pipelines);
• Exposure to working with Kubernetes for deployment and containerisation;
• Solid experience in SQL, database management, and related backend technologies;
• Strong preference for candidates with experience in large, established industries such as banking, insurance, and payment systems (e.g., Worldline, Euroclear, Mastercard);
• Experience in highly regulated or security-sensitive environments is a plus, given the nature of the project.

Competences

• A team player.
• Good communication skills.
• Capable of working in a fast-paced, innovative environment.

Languages

• Fluent in English.
• Dutch or French proficiency is a plus.