Senior Java Backend Engineer

Join our client, a pioneer in digital identity and fraud prevention solutions, serving banks, fintech firms, online marketplaces, and other regulated industries globally. Their innovative products harmoniously blend biometric identity verification, document and image processing, and sophisticated fraud detection techniques, empowering clients to deliver smoo…

Role Overview oscilar is hiring a Senior Backend Engineer with a focus on Java. This remote position is open to candidates based in Poland. The role centers on building and maintaining backend systems that support oscilar’s products and services. What You Will Do Work closely with teams across disciplines to design, implement, and support backend applications Develop scalable, reliable backend systems using Java Contribute to the ongoing improvement of code quality and system performance Location This is a remote role available to candidates located in Poland.

Join our dynamic team as a Kafka System Engineer, where you will engage with innovative colleagues to develop and enhance our event streaming platform powered by Apache Kafka. Your expertise in Kafka application development will be pivotal in driving our customers' success.Your core responsibilities will include designing, implementing, and maintaining our Kafka platform. You will also create and refine tools for monitoring, logging, and deployment processes. Furthermore, you will be responsible for preparing comprehensive documentation to facilitate the use of Kafka across the organization, ensuring all team members are well-supported in utilizing the platform effectively.

Join our innovative team at Nordsec as a Mid-Senior Backend Engineer specializing in Go. In this role, you will be responsible for designing and implementing robust backend solutions that drive our platform's performance and scalability. Collaborate with cross-functional teams to enhance our technology stack and deliver high-quality software solutions. Your expertise will contribute to our mission of providing secure and efficient digital services.

Join Box Inc. as a Mid-Level Java Engineer and take part in building innovative solutions that streamline processes and enhance user experiences. You will collaborate with a team of talented developers, contributing to the design, development, and maintenance of high-quality software applications.We value creativity, teamwork, and a passion for technology. If you are eager to tackle challenging problems and develop your skills in a supportive environment, we would love to hear from you!

Join Confluent, the leading platform for data in motion, as a Senior Staff Software Engineer specializing in Apache Kafka. In this remote role, you will play a pivotal part in enhancing our Kafka ecosystem, ensuring high availability and performance for our global clients. Your expertise will help shape the future of real-time data streaming.

Join our dynamic team at Renmoney as a Java Backend Developer, where you will contribute to our core engineering teams, including Banking, Loans, Core Tech Platform, and Cards. Our teams are focused on developing high-impact, backend-heavy systems that drive essential financial products and internal platforms.At Renmoney, we prioritize engineering excellence—not only in delivery speed but also in system quality and the artistry of software development. We are cultivating a collaborative engineering culture that values clear communication, thoughtful architecture, rigorous testing, and teamwork.Our tech stack includes: Java • Spring Boot • AWS (EKS) • MySQL • Kafka • Redis • Grafana • Prometheus.

Role Overview InPost is hiring a Java Software Engineer (Mid-Senior Level) in Kraków. This role focuses on building and improving software solutions that support the company’s products and services. What You Will Do Develop and maintain Java-based applications Collaborate with team members to design and implement new features Write clear, maintainable, and efficient code Contribute to code reviews and help ensure high standards Who We’re Looking For Experience working with Java in a professional setting Comfort working in a collaborative team environment Commitment to delivering quality software This position is based in Kraków and offers the chance to work on projects that support InPost’s growth and innovation.

About Our Team At SumUp, we provide a comprehensive Point-of-Sale (POS) solution designed to empower businesses such as cafes, shops, bars, and salons to streamline operations and foster growth. Our platform encompasses a variety of features including product catalogs, inventory management, business analytics, compliance assistance, and loyalty programs. The Fiscalization team is dedicated to ensuring compliance in countries like Italy, Sweden, Norway, Belgium, and Austria, among others. We are also pioneering the integration with third-party services for fiscalizing receipts. As a Senior Backend Engineer, you will work alongside a vibrant, cross-functional team comprising Product Managers, Designers, Engineering Managers, and fellow engineers. Your Role In this position, you will develop secure backend systems that ensure SumUp's POS products are compliant across various countries on our roadmap. You will collaborate with the Fiscalization squad to devise unique solutions tailored to the challenges in each market. We are looking for a developer who values user-centric design, precision, and seamless collaboration. You will excel in a structured communication environment and thrive in a cross-functional team. This is a B2B role based in Warsaw. Key Responsibilities Design and maintain fiscal compliance solutions to support SumUp's expansion across Italy, Sweden, Norway, Belgium, Austria, and other European markets. Develop integrations with third-party services for receipt fiscalization and regulatory reporting. Navigate SumUp's intricate POS ecosystem and familiarize yourself with fiscalization frameworks across multiple jurisdictions. Work collaboratively with team members and stakeholders distributed across 5+ cities in a hybrid working model. You Will Succeed in This Role If You Have: 5+ years of experience in backend engineering with expertise in Java and/or Kotlin. A solid understanding of system architecture, design principles, data modeling, and API development. Hands-on experience with distributed and fault-tolerant systems. Proficiency in AWS and Kubernetes. Strong knowledge of Kafka, PostgreSQL, and CQRS.

Join Turnitin as a Senior Fullstack/Backend Software Engineer, where your expertise in backend development, particularly with Java and serverless architectures, will be pivotal. We are seeking engineers who are enthusiastic about creating scalable distributed systems and delivering robust software solutions for our acclaimed educational platform.As an integral member of our shared services team, you'll spearhead the development and enhancement of the core systems supporting both our existing and upcoming applications.Key Responsibilities:Architect, develop, and optimize scalable backend services utilizing Java and serverless technologies (AWS Lambda).Design and implement RESTful APIs and event-driven architectures.Contribute to frontend component development as required.Enhance performance and cost-effectiveness of existing services.Collaborate with cross-functional teams, including Architects, Product Managers, and engineering leads, to deliver innovative solutions.Mentor junior developers and promote best practices.Establish and manage CI/CD pipelines.Maintain high-quality coding standards through peer reviews, automated testing, and compliance with development best practices.Document shared components comprehensively, providing usage guidelines and examples.

Join altersolutions as a Mid/Senior Java Developer and take part in exciting projects that shape the future of technology. In this role, you will leverage your expertise in Java development to create innovative solutions and enhance existing systems. You will collaborate with cross-functional teams to deliver high-quality software in a dynamic, fast-paced environment.

Apollo.io is a premier go-to-market solution empowering revenue teams globally. With a robust user base exceeding 500,000 companies and millions of users, our platform supports everyone from burgeoning startups to industry giants. Established in 2015, Apollo.io has rapidly ascended to become one of the most dynamic players in the SaaS sector, securing around $250 million in funding and achieving a valuation of $1.6 billion. We provide sales and marketing teams with instant access to verified contact data for over 210 million B2B contacts and 35 million companies worldwide, along with a suite of tools that streamline engagement and conversion on a unified platform. By facilitating accurate contact information retrieval and automating outreach processes, Apollo.io transforms prospects into loyal customers. In 2023, we successfully raised a Series D round and are supported by esteemed investors such as Sequoia Capital and Bain Capital Ventures, with industry leaders like JD Sherman, the former President and COO of Hubspot, on our board.**This is a Permanent role ("Umowa o pracę") and not a B2B contract** YOUR ROLE & MISSION As a Senior Backend Software Engineer at Apollo.io, you will play an essential role within our expanding team. Collaborating with cross-functional teams, you will implement best practices in technology, architecture, and processes. This position offers you the opportunity to thrive in an open and collaborative environment, where mentorship flows both ways, enabling you to grow and accelerate your career. Your passion for learning and teaching will be invaluable as you engage with design, front-end, analytics, and various teams beyond Engineering. You will relish solving complex problems collaboratively and making a tangible impact. At Apollo, you will be driven by a commitment to quality, relentlessly pursuing improvements in quality, automation, and bug resolution while investigating performance enhancements and innovative ideas.

Join HelloFresh as a Senior Backend Engineer in our Operations team, where you'll play a pivotal role in enhancing our backend systems. You will work closely with cross-functional teams to develop scalable and efficient solutions that power our meal kit delivery service.

Join Altersolutions as a Kafka Engineer and be part of an innovative team that is driving the future of technology. In this role, you will work on designing, implementing, and maintaining scalable and distributed systems using Apache Kafka. Your expertise will contribute to enhancing data integration processes and improving system reliability.

Join LoopMe, the premier in-app monetization and programmatic advertising platform. With a reach of over 900 million unique monthly users and the processing of more than 200 billion ad requests, our platform offers unparalleled opportunities for mobile app developers. The Chartboost SDK is recognized as the most-integrated independent mobile ad SDK, facilitating meaningful connections between advertisers and highly engaged audiences.What We Are Looking ForWe seek an experienced backend software engineer to become an integral part of our exchange team. Your mission will be to enhance our advertising platform, designed to handle hundreds of thousands of requests per second while conducting real-time auctions to deliver optimal ads from our global partners. We empower our engineers to take ownership of this vital system, overseeing the complete lifecycle of feature development—from initial design to production deployment.Our primary system is developed in functional Scala, providing opportunities to leverage your distributed, low-latency programming skills using modern technologies like MongoDB, protocol buffers, and more. As we transition from Scala to Java in the coming years, your expertise will be invaluable in guiding this change.Your ResponsibilitiesDesign, implement, and test functionalities for our Exchange product.Assist in the migration of our advertising exchange from Scala to Java.Collaborate effectively with engineers, system architects, and Operations teams to implement enhancements and resolve issues.Engage in technical discussions, proposing innovative solutions to enhance the product and processes.Troubleshoot application, technology, and infrastructure issues.Continuously expand your technical knowledge.Demonstrate creativity and independence while collaborating to maximize efficiency and throughput.Consistently deliver high-quality work on time and enhance developer productivity across the organization.Value clean code and possess experience in writing unit tests to maintain superior code quality.Your QualificationsBachelor’s degree in Computer Science or a related field.1+ years of Scala programming experience.2+ years of Java programming experience.6+ years of overall software engineering experience.Understanding of microservices with practical implementation experience.Experience in developing high-capacity, high-traffic, high-availability systems.Familiarity with Agile development methodologies.Preferred QualificationsExperience in advertising technology.Familiarity with Python or Java.Experience with NoSQL databases.

Join Netguru, a pioneering force in digital commerce, as we assist renowned brands in modernizing their B2B solutions, marketplaces, and retail ecosystems. Since our inception in 2008, we have empowered businesses through innovative technology, AI-driven personalization, and exceptional engineering and design teams. As a certified B Corporation®, we proudly serve major brands such as IKEA, VW, OLX, Delivery Hero, Żabka, Wolt, Careem, and Vinted.We are currently seeking a Senior Backend Engineer with robust architectural expertise to engage in a long-term project for a European client in the laboratory and biotech sector. This position is a single-developer project, requiring close collaboration with the client’s internal teams and laboratory stakeholders to clarify requirements, outline the project scope, and enhance existing backend processes. Strong communication skills are vital, as you will frequently participate in technical discussions with LIMS and laboratory teams. Your role will encompass hands-on development, legacy code refactoring, and contributing to a scalable, well-structured backend architecture. Please note that candidates must be based in the EU due to client stipulations.Position: Senior Backend Engineer (Java / Architecture)Contract: Freelance / B2B – Remote (EU Only)Rate: 36–50 EUR/hourLanguage: English C1Key ResponsibilitiesOperate independently as the sole backend engineer on the project.Refactor and modernize legacy backend systems.Enhance and expand existing microservices and backend integrations.Maintain and develop REST and SOAP interfaces.Engage with laboratory teams and LIMS stakeholders to define requirements.Guarantee stable operation of backend services in an on-premise Kubernetes environment.Work collaboratively with internal client teams to ensure architectural consistency.QualificationsTechnical Skills & ExperienceExtensive experience with Java (Spring / Spring Boot).Strong architectural and problem-solving abilities.Proficient in designing and maintaining REST APIs.Familiarity with SOAP services.Experience in microservices environments.Hands-on experience with Kubernetes (preferably on-premise setups).Background in working with or integrating LIMS systems.Solid understanding of refactoring and modernizing legacy code.Excellent communication skills for direct collaboration with laboratory stakeholders.Proficiency in English at C1 level.Must be based in the European Union.BenefitsIn return, we offer:100% remote, flexible work environment;Access to cutting-edge technology and tools;Opportunities for professional development.

N-iX is on the lookout for a Senior Python Engineer with proficiency in Go and Java to become a vital part of our innovative team. In collaboration with our client's team, you will contribute to the development of a state-of-the-art cloud-based security platform as a backend engineer with a robust infrastructure background. This team is dedicated to creating solutions that empower security teams to conduct forensic investigations, deploy custom scripts on a large scale, and react swiftly to cyber threats affecting millions of endpoints. The platform facilitates automated collection of forensic evidence, customizable forensic profiles, and efficient incident response workflows, all integrated within a single console alongside EDR data. Your primary focus will be on enhancing backend systems and infrastructure to enable the team to deliver high-quality solutions more efficiently.

Hello We are Bïrch, a transformative platform designed for creative and growth marketing teams, encompassing content creation, collaboration, and ad campaigns all in one powerful toolbox. With over 9 years in the business, we proudly serve more than 800 companies and 5,500 marketers. Our platform has facilitated billions in ad spend, positioning us as one of Meta's fastest-growing partners, officially endorsed by both Meta and Google. Following our rebranding from Revealbot to Bïrch, we have documented our transformative journey here.As we transition from a single successful product to a multi-product platform, we launched Bïrch Hub last year in collaboration with Meta, a user-friendly server-side tracking tool for ads. To support our ongoing growth, we are expanding our backend team. In this position, you will not only maintain existing systems but also play a pivotal role in developing new products and services, shaping architecture collaboratively, and making significant technical decisions by writing high-quality code across our dual-language backend using Ruby on Rails and Go. About UsWe are a remote-first team of friends scattered across the globe, with our headquarters located in Barcelona. Having already established a successful product, we are now embarking on a broader vision. We hire talent worldwide and cherish our offline meetups: in the last two years, we gathered in Barcelona, and previously, in Istanbul. Check out our team’s Instagram to learn more about our diverse cultures and backgrounds.

Join our innovative team at dev2 as a Backend Software Engineer where you will play a crucial role in developing scalable backend solutions. Your expertise will help shape our technology stack and improve system performance. You will collaborate with cross-functional teams to design, implement, and maintain high-quality applications.

Role overview Talan is seeking a Mid-Level Backend Spark Developer to join the team in Warsaw. This role centers on building and maintaining backend systems, with Apache Spark as a primary tool. The work directly supports ongoing projects and plays a key part in meeting team objectives. What you will do Develop backend solutions that use Spark as a central technology Collaborate with colleagues from various disciplines to deliver dependable software Support project progress by helping meet milestones and upholding technical standards Location This position is based in Warsaw.