Senior Java ETL Data Engineer

About the Position

Senior Java ETL Data Engineer

Brussels, Brussels, Belgium

Our SynaptiQ platform collects near-real-time data from more than 20 million devices across thousands of utility-scale solar and wind sites worldwide. Everything the platform does - the analytics, the alarming, the reporting our clients run their portfolios on - depends on that data arriving complete, on time and correctly normalised. To keep that foundation solid as the portfolio grows, we are looking for a Senior Java ETL Data Engineer to own the technical direction of the engine that makes it happen.

You will join our Product Engineering organisation, working in a small cross-functional team of 2–3 engineers and reporting to an Engineering Manager. You will work closely with Product Management to define both what gets built and how it is implemented, and with Operations when things break. The working language is English. Day to day you will be in high-performance Java, S3-compatible object storage (S3, ABS, GCS), streaming infrastructure, and Linux.

This is a senior individual contributor role. You will own the ETL engine - not a slice of it - and day-to-day:

• You design, develop and operate the Java ETL engine that processes near-real-time data from millions of renewable energy assets. Ownership here runs from conception through to production operation: you build it, you run it, you fix it.
• You architect and integrate the engine with S3-compatible object storage and streaming infrastructure. Deciding how and when we adopt a given storage or streaming technology is your call to make and justify.
• You balance the technical trade-offs between real-time and batch processing, and make those calls on evidence rather than preference.
• You take the lead on quality and reliability through code review, testing and SRE practice - including incident response and postmortem analysis when something goes wrong at 2am on a Sunday.
• You decompose pipeline problems into actionable milestones and plans, so the team knows what "done" looks like before work starts.
• You maintain the architecture decisions, runbooks and API documentation that let the rest of us operate what you build.

Responsibilities

• Design, develop, and operate the Java ETL engine
• Architect and integrate the engine with S3-compatible object storage and streaming infrastructure
• Balance technical trade-offs between real-time and batch processing
• Lead on quality and reliability through code review, testing, and SRE practices
• Decompose pipeline problems into actionable milestones and plans
• Maintain architecture decisions, runbooks, and API documentation

Requirements

• 7+ years of software engineering experience, including at least 3 years writing and operating high-performance Java in production
• Deep understanding of Java concurrency, parallelism, and performance optimization
• Hands-on experience with data processing pipelines on S3-compatible object storage
• Comfortable with Linux system administration
• Delivered and operated production systems end-to-end - code review, testing, monitoring, incident response
• Architectural thinker who evaluates technologies on evidence
• Master's in Computer Science, Engineering, or equivalent by experience
• Fluent in English (speaking and writing)
• Ability to work autonomously
• Ability to explain technical trade-offs to non-engineers

Nice to Have

• Experience with streaming platforms (Kafka, Flink, or Pulsar)
• Experience with time-series databases
• Renewable energy sector experience

We Offer

Our offices are hidden in the centre of Brussels with a view on a pond, with ducks and a heron bringing a regular visit. In addition to a stimulating atmosphere in a highly motivated group of people, 3E offers a unique opportunity to further develop yourself in a company/team with an ambitious growth plan, delivering innovative services.

Furthermore:

• On-the-job training by our experts
• Flexibility, responsibility, and freedom in your day-to-day work
• An international environment with projects in over 100 countries worldwide, colleagues of over 20 nationalities

We are open to both independent contractors (commitment to 219 invoiced days/year) or payroll contracts. For a Belgian payroll contract, the extralegal benefits are:

• Home working (2 days per week)
• Hospitalisation insurance
• Pension saving
• Representation allowance
• €9 meal voucher/day
• Flexible income plan
• 20 legal days off + 12 compensation days (per full year worked)
• Sustainable transport subscription and/or bike allowance (€0.36/km)

About the Company

At 3E, we are dedicated to providing innovative services and solutions in the renewable energy sector. Our team is highly motivated and committed to delivering excellence. We offer a stimulating work environment and opportunities for professional growth.