Senior Java Developer

Salary: up to 1600 PLN/ MD na B2B Working model: 100% remote or hybrid Warsaw/ Poznań/ Kraków/ Rzeszów/ Gdynia Why choose this offer? Build a brand-new AdTech platform , shaping the core architecture and setting technical standards for a major e-commerce organization Work directly with cutting-edge advertising ecosystems (Meta, TikTok, Google) and gain rare hands-on experience with walled-garden APIs at scale Join a newly formed, highly impactful team , where your decisions significantly influence the platform, technology stack, and long-term direction Develop highly scalable, data-intensive backend systems, solving complex engineering challenges related to real-time campaign data , API limits, and high availability Project Project focuses on building a new advertising platform from the ground up for a major e-commerce company. The platform will enable the management, execution, and optimization of advertising campaigns both within the company's internal ecosystem and across external walled-garden platforms such as Meta, TikTok, and Google . The newly formed team will own the backend layer of the system, develop integrations with major advertising APIs, and design a scalable architecture capable of handling large volumes of campaign data. What you will be doing on this postion: Designing and developing the backend of an AdTech platform that manages campaigns across multiple marketing channels Integrating with advertising APIs from leading walled-garden platforms: Meta Ads API, TikTok Marketing API, Google Ads API, Facebook Marketing API Implementing campaign logic, data ingestion, scheduling mechanisms, reporting pipelines, and optimization components Designing architecture for high scale , high performance, and high availability (handling large data volumes, respecting API limits and throttling) Building and maintaining data models for advertising metrics (impressions, clicks, spend, conversions, audiences) Ensuring quality, reliability, observability, and testability of backend components. Collaborating closely with product teams, data engineers, and AdTech specialists to expand platform capabilities Expected competences and knowledge Java (8/11) and strong foundations in concurrency High-performance systems: low latency, high throughput, handling extremely high QPS Distributed systems : Kafka , Aerospike/Redis, Cassandra, Kubernetes Real-time bidding (RTB): understanding how auctions work, 50-100 ms timeouts, OpenRTB protocols Working with logs and events: stream processing (Flink/ Spark), large data volumes APIs and integrations, familiarity with technologies such as, or similar to: OpenRTB, pixel tracking, ad-server APIs Profiling and optimization: GC tuning, memory footprint, latency debugging Nice to have: How DSP, SSP, Ad Server, and DMP work Targeting mechanisms, frequency capping, attribution Privacy constraints: GDPR, ITP, third-party cookie limitations Experience with bidding engines or recommendation systems Knowledge of Go or Scala (commonly used alongside Java ) Understanding auction economics and campaign optimization Technologies you'll work with Java microservices Docker Kubernetes Kafka Client – why choose this particular client from the Jit portfolio? Our Client dominates the Polish e-commerce arena as the market leader since 1999 . With a user base of over 20 million and growing, this well-established platform is at the forefront of e-commerce, constantly striving for growth through market expansion and investment. As a major player in technology, our Client boasts a talented IT team of over 1,000 employees who focus on developing their own cutting-edge technologies. Jit Team has had a successful partnership with our Client since spring 2021 , with multiple software development teams dedicated to our Client's platforms. These teams operate autonomously, designing platform components through micro-services. Working with our Client offers a chance to contribute to a solution used by millions on a daily basis and to tackle the challenge of delivering software at a massive scale , where even a single second of delay can have a significant impact. This project provides a unique opportunity to work with state-of-the-art technologies and tools, making it a rare and valuable experience. About Jit Team The Human factor of IT - it's not just a slogan, it's a philosophy. The foundation of Jit Team is people, which is why we prioritise you. We employ over 700 experienced experts . We create highly specialised teams for clients from all over the world. We offer team members developmental projects, a wide range of benefits and a proprietary professional development programme. Behind our maxim are also charitable and educational activities. We support pupils and students by donating learning equipment. We offer internships to help launch careers in IT. We support water rescuers and hospitals by providing the necessary equipment. We are a Polish company and we share what we have achieved over 15 years of activity . By supporting indigenous initiatives, we ensure the circulation of good energy.