(Senior) Java Developer - Freelance

Description Netguru 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®, Netguru 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.