Senior Java Developer

We are seeking a skilled and experienced Senior Java Engineer to join our dynamic team working on an innovative AI project in Europe. Our client, a leading American e-commerce giant based in California, operates one of the most renowned and successful platforms globally, connecting millions of sellers and buyers across more than 190 markets. Key Responsibilities: Design and implement a robust and scalable Kotlin framework for configuring and managing AI agents. Develop clean, maintainable, and efficient code adhering to established coding standards. Ensure optimal performance, quality, and responsiveness of the platform. Identify and resolve bottlenecks and errors promptly. Contribute to maintaining high code quality, organization, and automation. Create and update technical documentation for the framework/platform.

Join our dynamic team as a Senior Java Engineer and contribute to an exciting AI project in Europe. We are seeking skilled individuals who are passionate about technology and eager to make a significant impact.Our client, a renowned leader in global e-commerce based in California, operates one of the most frequented and successful websites on the Internet. This platform connects millions of buyers and sellers across over 190 markets worldwide, creating a vibrant online marketplace.Key Responsibilities:Design and implement a robust and scalable Kotlin framework for managing AI agents.Write clean, maintainable, and efficient code adhering to our coding standards.Optimize the performance, quality, and responsiveness of the platform.Identify and resolve bottlenecks and bugs.Maintain high standards of code quality, organization, and automation.Develop and sustain technical documentation for the framework.

N-iX is a prominent global software development firm established in 2002, uniting over 2,400 skilled tech professionals across more than 40 countries. We specialize in delivering cutting-edge technology solutions in cloud computing, data analytics, artificial intelligence, embedded software, Internet of Things (IoT), and more, serving industry leaders and Fortune 500 companies worldwide. Join our mission to develop technology that brings significant transformation to businesses and individuals globally.We are seeking a skilled Senior Software Engineer to contribute to our AI project in Europe.Key Responsibilities:Design and implement a robust and scalable Kotlin framework and platform for configuring and managing AI agents.Develop clean, maintainable, and efficient code adhering to our coding standards.Ensure optimal performance, quality, and responsiveness of the framework/platform.Identify, troubleshoot, and resolve bottlenecks and errors.Assist in maintaining code quality, organization, and automation processes.Create and manage technical documentation for the framework/platform.

toloka-ai seeks a Senior Consultant with a background in management consulting at MBB or other top-tier firms. This freelance role centers on AI projects and is open to candidates based in Poland who prefer remote work. Role overview This position involves guiding strategy and execution for AI initiatives. The Senior Consultant will use consulting experience to help achieve project objectives and work closely with teams to develop practical AI solutions. What you will do Advise on strategic direction and implementation for AI projects Apply consulting knowledge to support project outcomes Work with cross-functional teams to define and refine AI solutions Requirements Experience in management consulting at MBB or a similar top-tier firm Strong strategic thinking and problem-solving abilities Interest in AI and new technologies Located in Poland with the ability to work remotely

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 smooth digital experiences while upholding robust security measures and compliance with regulations. The company harnesses the power of AI, machine learning, and computer vision to enhance identity verification, mobile deposit, and liveness detection solutions utilized by thousands of organizations worldwide.About the RoleWe are in search of a Senior Java Backend Engineer to become a crucial member of our cross-functional team dedicated to developing cloud-native identity and fraud prevention products on AWS. In this pivotal position, you will architect and implement scalable, high-performance backend services and APIs in Java, operating within a microservices and serverless architecture. You will engage in close collaboration with product managers, front-end engineers, researchers, and DevOps specialists to deliver production-ready features that enable real-time identity verification and extensive fraud detection.What You Will DoDesign, develop, deploy, and maintain production-ready backend APIs and microservices in Java, primarily utilizing AWS as the deployment platform.Construct scalable and resilient services leveraging serverless and containerized architectures (ECS, Lambda, API Gateway).Write clean, efficient, and testable code, emphasizing quality engineering and continuous delivery.Design and execute robust automated test suites, including unit, integration, and performance tests.Collaborate with product managers, front-end engineers, QA, and cloud operations teams to translate requirements into well-crafted features.Contribute to the development of CI/CD pipelines and advocate for DevOps best practices to ensure rapid and reliable deployments.Create and maintain both internal software and public API documentation.Participate in Agile ceremonies such as stand-ups, sprint planning, refinements, and retrospectives.Mentor and support junior team members, sharing knowledge to elevate team capabilities.

Mission Statement: Kontakt.io is creating a transformative platform for care operations.Our innovative solutions minimize waste, reduce costs, and enhance revenue by optimizing throughput, asset utilization, and staff productivity. Utilizing AI, Real-Time Location Systems (RTLS), and Electronic Health Record (EHR) data, our platform empowers self-learning agents to streamline workflows, adapt in real-time, and manage all care delivery operations efficiently.Designed for easy deployment and scalability, our platform offers a comprehensive view of spaces, equipment, and personnel, thereby eliminating inefficiencies and enriching the patient experience. With a demonstrable 10X return on investment and over 20 successful use cases, Kontakt.io stands as the premier choice for enhanced and expedited care delivery operations.To thrive in this role, you must possess a fervent passion for developing high-performing and dependable applications. We seek individuals who are innovative problem solvers, eager to adopt the best tools for addressing scalability challenges.Our technology stack includes: - Backend: Kotlin, Java 15+; Spring Boot, Spring Data, Kafka, MongoDB, PostgreSQL, Docker, Kubernetes, Python, AWSWe are in search of a self-motivated individual who can approach challenges from a product perspective, propose effective solutions, and execute them successfully.

Join our dynamic team at inpost as a Senior Java Engineer. We are seeking an innovative and experienced software developer who is passionate about building high-quality applications. In this role, you will be responsible for designing, developing, and maintaining robust Java-based solutions while collaborating with cross-functional teams to enhance product functionality.

Join our dynamic team at Soprasteria as a Senior Software Engineer specializing in Java development. In this role, you will design, develop, and maintain high-quality software solutions that meet our clients' needs. Your expertise will contribute to innovative projects that make a real impact.

We are seeking a Senior Java Engineer with a strong background in Python and Golang to join our dynamic team.About Us:Our client is at the forefront of cybersecurity innovation with their XDR platform, which autonomously prevents, detects, and responds to threats in real-time. The Singularity XDR leverages patented AI models, providing organizations with comprehensive visibility and control over their networks to mitigate every stage of the threat lifecycle.We pride ourselves on a values-driven culture where every team member is recognized, results are celebrated, and professional relationships flourish. Our core values—trust, accountability, relentlessness, and ingenuity—guide our collaborative global team. If you're passionate about innovative problem-solving, we'd love to discuss how you can contribute to our success!About the Team & Role:You will be part of a team dedicated to ensuring the security of millions of devices worldwide across various operating systems (Windows, Linux, macOS) while processing billions of security events daily.We are developing services such as gateways, caching solutions, and threat data ingestion systems that facilitate two-way interactions between client's agents on secured devices and our cloud-based management console.Our console empowers thousands of users in IT security teams to manage security software deployed on endpoints, enabling them to investigate threats, receive notifications, and create blocklists, exclusions, policies, and more.Joining our core team means you'll have a significant influence on how we protect our customers' environments (including Fortune 10 companies and numerous Global 2000 entities) and enhance their security postures.

Role overview As a Senior AI Engineer at SmartRecruiters, based in Poland, the focus is on building and refining artificial intelligence solutions that drive the company’s products. This role shapes the scope of new projects and helps set the direction for AI technology within the organization. What you will do Lead the design and development of AI features and systems Work on projects that expand and improve AI product capabilities Collaborate with colleagues to address and solve technical challenges Requirements Professional experience in artificial intelligence engineering Strong interest in technology and its practical uses Drive to make a meaningful contribution in the AI field

About Us1GLOBAL is an innovative technology leader in mobile communications, offering unparalleled global connectivity solutions for both enterprises and consumers. Our cutting-edge telecom platform features a robust, owned global mobile core network, state-of-the-art in-house developed eSIM technology, and a wide array of telecom licenses, allowing us to operate as a fully regulated telecommunications provider in 40 countries around the globe.We proudly serve some of the world’s most prominent banks, enterprises, and digital-first businesses, including neo-banks, global FMCG leaders, travel industry giants, and payment service providers. Currently, we empower over 70 million people and devices worldwide, facilitating our clients to launch, scale, and innovate confidently within the mobile ecosystem.1GLOBAL is a rapidly growing, profitable entity, projecting full-year revenues exceeding US$200 million and profits over US$25 million by 2025. Our robust cash flow supports continuous investments in infrastructure, platform innovation, and global expansion. Recent years have been pivotal for us, marked by significant enterprise and consumer client acquisitions that enhance our status as a formidable global mobile connectivity provider, dedicated to helping consumer brands thrive in telecommunications.Founded in 2022 by seasoned technology entrepreneurs Hakan Koç and Pyrros Koussios, 1GLOBAL is at the forefront of shaping the future of global telecommunications. We operate as a fully regulated Mobile Virtual Network Operator (MVNO) in 12 countries and as a regulated telecom operator in an additional 28 markets. Headquartered in the Netherlands, with premier R&D centers in Lisbon, Berlin, and São Paulo, our team of nearly 500 experts across 15 countries is unified by a singular mission: to redefine global mobile connectivity through unparalleled technology, scale, and operational excellence.About the TeamThis senior, hands-on Java position focuses on scalable backend systems, long-term ownership, and addressing real-world production challenges. You will be part of a newly formed backend team in Warsaw, dedicated to advancing our eSIM, global connectivity platform, and IoT solutions.The role entails:Enhancing and modernizing existing systems,Developing new services and greenfield components,Boosting reliability, performance, and maintainability across the platform.As a senior engineer, you will also lead the evolution of testing methodologies as systems evolve.

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.

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.

zooplusse seeks a Senior Software Engineer with solid experience in Java and Kotlin to join the team in Krakow. Role overview This position centers on designing and building software solutions that enhance user experience and align with business objectives. The work involves hands-on development with Java and Kotlin, focusing on both new features and the ongoing performance of applications. What you will do Create and implement software that supports business needs and improves usability Collaborate with cross-functional teams to define requirements and deliver new features Maintain a strong emphasis on application performance, quality, and responsiveness during development Collaboration This role works closely with colleagues from various disciplines. Each release aims to meet high standards and provide meaningful value to users and the business.

Please submit your CV in English and specify your English proficiency level. Mindrift connects experienced specialists with project-based roles in artificial intelligence. Assignments focus on evaluating, testing, and improving AI systems for leading technology companies. All roles are project-based and do not represent permanent employment. Role overview This freelance contract is for an Optical Engineer based in Poland, working remotely. Contributors join for specific projects and handle assignments that support AI development. Work is organized around distinct tasks with clear deliverables. What you will do Create original optical problems that reflect real-world physics research workflows Design computationally intensive problems, often requiring days or weeks to solve manually Develop challenges involving complex reasoning in mechanics, electromagnetism, thermodynamics, and quantum mechanics Base problems on actual research questions or practical applications in optics and physics Document each problem thoroughly and provide verified, accurate solutions Requirements Degree in Physics (theoretical, experimental, or computational) or a related discipline Minimum of 2 years of professional experience in applied, research, or teaching roles Background in numerical simulation techniques Ability to design problems that reflect authentic physics research practices Creative problem-solving skills across several areas of physics Familiarity with modeling and approximation methods Strong written English skills at C1 level or higher Process The workflow includes applying, passing qualifications, joining a project, completing assigned tasks, and receiving compensation. Time commitment Active project phases typically require about 10–20 hours per week. Actual hours may vary depending on project needs. This estimate applies only while projects are active and does not guarantee a set workload. Compensation Contributors may earn up to $29 per hour, depending on experience and the speed of contributions. Pay rates can vary by project based on scope, complexity, and required expertise.

Role Overview Endava is looking for a Senior Java Developer in Gdansk. This role focuses on building and refining software solutions for clients. The position involves designing, implementing, and improving complex Java applications. What You Will Do Design and develop Java-based applications Optimize existing systems for better performance and reliability Work closely with colleagues from different disciplines to integrate solutions

Zooplusse seeks a Senior AI Engineer in Krakow to design and build advanced artificial intelligence solutions. This position involves hands-on work with a diverse team, contributing technical expertise to projects that impact millions of users. Role overview This role focuses on developing and implementing AI technologies. Collaboration with colleagues from various backgrounds is central to daily work, ensuring that solutions are both innovative and practical. What you will do Design and build AI systems to support large-scale projects Work closely with team members from different disciplines Contribute to technology that reaches a wide user base Location This position is based in Krakow.

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.

Join our dynamic team at Talan as a Senior Java Developer specializing in e-Trading solutions. We are seeking innovative and experienced developers who are passionate about building high-performance trading platforms. You will work closely with cross-functional teams to design, develop, and optimize our trading applications.As a Senior Java Developer, you will leverage your expertise in Java technologies, agile methodologies, and your understanding of financial markets to deliver robust and scalable solutions.