(Senior) Java Developer - Freelance

Description

the company is a trusted partner in digital commerce. The company helps leading brands modernize B2B solutions, marketplaces, and retail ecosystems. Since 2008, it has empowered businesses with cutting-edge technology, AI-powered personalization, and world-class engineering and design teams. A certified B Corporation®, the company is trusted by major brands including IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.



Position: Senior Backend Engineer

Contract: B2B – Remote (EU Only)

Rate: up to 30 EUR/hour + 20 paid vacation days

Language: English C1


Responsibilities

• Design and build scalable backend systems for processing large volumes of spare parts data

• Develop and maintain robust, high-performance APIs for data integration and access

• Build, optimize, and maintain ETL pipelines for data ingestion and transformation

• Process and manage large datasets in distributed environments

• Optimize system performance, latency, and throughput across backend services

• Improve database performance through indexing, schema design, and query optimization

• Collaborate with product managers, designers, and engineering teams to deliver scalable solutions

• Work closely with stakeholders to define and implement data-driven functionalities

• Ensure high standards of security, reliability, scalability, and maintainability

• Mentor and support other engineers as part of a senior-level engineering role

• Stay up to date with modern backend technologies, architecture patterns, and engineering best practices

Requirements

• Tech stack & requirements

  • Strong commercial experience with JVM-based languages such as Java, Scala, or Kotlin

  • Solid experience with relational databases, including PostgreSQL and MySQL

  • Experience working with NoSQL databases, preferably MongoDB

  • Hands-on experience processing and managing large datasets

  • Strong knowledge of scalable API design and backend architecture principles

  • Experience designing distributed and high-performance systems

  • Practical experience building ETL pipelines using standard data processing tools

  • Experience with cloud platforms such as AWS, GCP, or Azure

  • Strong understanding of performance optimization and low-latency systems

  • Experience with database optimization, including indexing, schema design, and performance tuning

  • Strong problem-solving and communication skills

  • Senior-level mindset with the ability to mentor and support engineering teams

  • English at C1 level

  • Must be based in the European Union

Benefits

In return, we offer:

• 100% remote, flexible work;

• work with an experienced team of developers and continuous development of your hard and soft skills;

• dev-friendly processes such as Continuous Integration, Continuous Delivery, Code Review and bug bashes;

• long-term collaboration on challenging products (FinTech, B2B software, E-commerce and more).

What will happen next?

• We would like to know you better, so we will invite you for a meeting with our recruiter.

• Next, you'll be asked to solve the task or invited to an interview and pair programming with one of our iOS Developers.

Looking for a full-time job? Check out our and find out more about our open recruitment processes.

If you need any disability-related adaptation at any step of the recruitment process – simply let the recruiter know! We'd be happy to help.