We bring startups and disruptive tech companies to the local market, offering engineers the opportunity to work on innovative, high-impact products. Join us and become a member of their R&D team while we take care of employment, HR support, a benefits package, and an enjoyable work environment.We’re looking for Senior Data - Software Engineer to join the team at a performance-marketing agency that works across more than 25 industry verticals. They focus on using advanced data analytics and tailored creative strategies to drive conversions — the agency handles everything from lead generation and campaign optimisation (through search, social media and newer platforms) so their clients can focus on growth. Responsibilities Design, build, and maintain high-performance, reliable data systems, including real-time pipelines, tracking infrastructure, and Feature Store foundations to support analytics and ML production Develop low-latency, scalable data services capable of handling high-throughput workloads in distributed systems Collaborate closely with ML teams to ensure features and data are accurate, consistent, and readily available Design and implement data ingestion pipelines, storage schemas, and data quality frameworks to maintain robust and reliable data infrastructure Apply software engineering best practices - clean code, testing, and system design - to ensure maintainable, high-quality solutions Requirements Strong software engineering fundamentals (clean code, testing, system design) Proven experience building real-time, low-latency data services Experience operating in production at scale (high throughput, distributed systems) Strong background with modern data stack (e.g., Kafka/Kinesis, Spark/Flink/Beam,Snowflake/BigQuery/Redshift) Ability to design schemas, ingestion flows, and data quality frameworks Experience collaborating with ML teams on feature availability and consistency Nice to Have Experience supporting ML systems (feature serving, online/offline consistency) Production experience with model inference pipelines Strong DevOps experience (Docker, Kubernetes, CI/CD) Experience with cloud-native architectures (AWS/GCP) Experience implementing data observability / lineage frameworks Benefits Work in a highly professional team. Informal and friendly atmosphere in the team Paid vacation — 20 business days per year, 100% sick leave payment Equipment provision Partially compensated educational costs (for courses, certifications, professional events, etc.) Legal and Accounting support in Poland Ability to work from our comfortable downtown office in Warsaw 5 sick days per year Medical insurance (after the end of the probationary period) English and Polish classes 2 times a week (online) Bright and memorable corporate life: corporate parties, gifts to employees on significant dates