Location: Poland (Remote/Flexible) We Are: RTB House is a global company that provides state-of-the-art marketing technologies for top brands and agencies worldwide. Its proprietary ad-buying engine is the first in the world to be powered entirely by Deep Learning algorithms, enabling advertisers to generate outstanding results and reach their goals at every stage of the funnel. We are looking for Senior Engineers to support our Bidding Platform organization which is the core of the RTB business, processing over 20 million requests per second to participate in real-time auctions and display advertisements to customers from 90+ countries. If you want to work on technically complex and demanding solutions, this is the opportunity for you! Our Senior Engineers are experts who combine deep technical expertise with a strong sense of ownership, and they take on Tech Lead roles in complex, cross-team projects. You will: Design and lead implementation of system changes that deliver high performance, scalability and observability for displaying and tracking ads world wide. Develop tools and optimizations to drive measurable improvements in critical user performance metrics. Implement, test, deploy, monitor and maintain (in all aspects, including setting up environment, writing configuration code, monitor production) HTTP / gRPC services and batch jobs in Java and Python, ensuring adherence to the high engineering standards. Provide hands-on technical leadership: solving complex system challenges, participating in planning and scoping of projects, and ensuring the implementation of the highest coding standards through participation in code reviews. Requirements: Excellent understanding of how complex IT systems work - from the hardware level, through software, to algorithms. Very good knowledge of fundamental Internet protocols and technologies (DNS, HTTP, cookies and others). Good knowledge of basic methods of creating concurrent programs and distributed systems (from thread level to geo-distributed clusters level). Practical ability to observe, monitor and analyse the operation of production systems (and draw valuable conclusions from it). The ability to critically analyze the solutions created in terms of performance (from estimating the theoretical performance of the designed systems to detecting and removing actual performance problems in production). General knowledge of issues (typical problems and methods of solving them) in the areas of 'high scalability' and 'high availability'. C1 level in English and Polish. Nice to have: Experience in the AdTech/Real Time Bidding space. Experience contributing to Real User Monitoring (RUM) systems. Selected technologies used: Java, Python Aerospike, Memcached Google Cloud Platform, BigQuery, MinIO Kafka, Clickhouse PostgreSQL Elasticsearch Kubernetes, Prometheus Jenkins, Graphite We Offer: Projects focused on extreme performance and high code quality – clean code and solid code reviews are our standard. Collaboration within an interdisciplinary, self-sufficient team (including DevOps, database experts, backend developers, product designers, and QA engineers). Access to modern technologies and the opportunity to apply them in large-scale, high-impact projects. Cooperation based on B2B contract. You can cooperate 100 % remotely or choose one of our office spaces in Warsaw or Cracow. Apply now You don't need to tick every box to apply. If you are passionate about software engineering, send us your CV, and we'll review it.