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Technology Lisbon, Portugal

Backend Java Developer

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Do you want to work with Big Data and help reducing CO2 emissions?

We are now looking for a full-time Backend Java Developer to join our RELEX family in our new Lisbon office. You’ll join one of our business logic development teams who will help you succeed in your new role. Together these teams implement algorithms for improving replenishment and optimizations for RELEX’s retail customers globally. By doing this you will be contributing, every day, to reduce overall food waste.

What you’ll be working on:

You will be working on parts of our software written in Java (currently v11), Kotlin and JRuby. Your work consists of implementing new features including calculation algorithms and data structures. You also get to improve existing ones by profiling and optimizing them. For the data storage we use our in-house-built in-memory database, which stores tens of billions of rows of data. It is deployed on a clustered platform to achieve high availability and horizontal scalability. The code runs on servers with over a hundred cores, so concurrency and parallelization are something that we put emphasis on using functional and immutable paradigms together with efficient memory usage.

What you’ll bring to the table:

You have a genuine interest in implementing complex algorithms in Java and solving non-trivial problems in a performant way, you also know what pros and cons different data structures have when it comes to CPU and memory usage and how to measure it. Previous experience of working with large databases is also seen as valuable, and you understand the importance of writing good covering tests and doing thorough code reviews. Being eager and open-minded to learn new things is of course seen as a big plus!

What we offer you in return:

  • A sense of purpose for your work. You will know that your daily commitment is effectively reducing CO2 emissions (…and we can measure it)
  • Possibility to be one of the first team members in the Lisbon branch. This means that you will be able to influence the culture and development of the place you will be working at
  • Work-life balance
  • Flexible work hours and a possibility to work remotely
  • An international career and learning opportunities in a rapidly growing software company
  • A fun, ambitious, and committed team of smart people to work with
  • A respectful and professional, yet easy-going atmosphere where individual thinking is encouraged
  • Mobile phone, data plan, health care insurance for you and your family
  • One day per week to work on off-topics (self- development, new ideas…)
  • Competitive salary

Are you the one we’re looking for? Apply today and become a part of our RELEX family!

You can apply by sending your cover letter and resume through the application form as soon as possible, but no later than 31st of December. Please note that we will fill this position as soon as we’ve found the right person, so we recommend that you act quickly.

If you have questions, Rui Morais (rui.morais[a] is happy to answer them.


RELEX Solutions is a leading provider of cutting-edge retail optimization software. We offer our customers radically improved demand forecasting and supply chain optimization, which then can be leveraged into exponential benefits — optimizing store space, allocation, workforce, pricing and promotion strategies, all within our unified platform.

RELEX is trusted by leading retail brands including Media Markt, Leroy Merlin, Dia, Mercadona, Auchan, Ahold Delhaize and many, many more, and has offices across North America, Europe, and the Asia Pacific region.