Senior Java Engineer

Location: Montenegro; Slovenia; Slovakia; Moldova; Romania; Poland The position is open for a global, publicly traded AdTech market leader. The company's platforms handle over 1 trillion requests per day, operating within a highly optimized real-time cloud architecture across dozens of servers and processing terabytes of data daily. The engineering team focuses on intense performance optimization, low-latency infrastructure, asynchronous data streaming, and cutting-edge GenAI research and development. Salary: upto $5,000 USD / month. Format: Full-time. Hybrid (Budva, Montenegro) or 100% Remote globally Contract Type: B2B Contract Responsibilities Design, scale, and maintain real-time advertising bidding systems (DSPs, RTB Exchanges, and SSP platforms). Optimize backend services using Java (Spring Boot / WebFlux) and Go (Golang) to meet strict low-latency SLA/SLO targets. Build and manage data-intensive architectures utilizing high-load storage solutions (Aerospike, ClickHouse) and event-driven messaging (Apache Kafka). Participate in R&D initiatives involving GenAI, integrating Agentic AI frameworks (LangChain, LangGraph, N8N) for workflow automation and predictive analytics. Take full ownership of features end-to-end, contributing to the frontend layer (React / TypeScript) for internal tools and dashboards when required. Requirements 5+ years of commercial software development experience with Java as the primary language. Deep knowledge of the Spring ecosystem (Boot, Data, MVC, Security, Cloud) and strong practical experience with reactive/asynchronous programming (Spring WebFlux / Project Reactor). Solid understanding of distributed systems, concurrency, and performance tuning at the JVM level. Strong verbal English skills at B2 level or higher, with the ability to explain architectural decisions and collaborate directly with a global engineering team during voice calls. Location outside of the Russian Federation due to contractual and payment restrictions. Candidates from Belarus are eligible only if they possess an active legal entity/IP in Georgia or Europe for international payments. Commercial programming experience or strong familiarity with Go (Golang). Hands-on experience with high-load and Big Data tools including Apache Kafka, ClickHouse, and Aerospike. Real-world experience or deep interest in LLMs and AI orchestration tools such as LangChain, LangGraph, or N8N. Familiarity with frontend development using ReactJS and TypeScript. Benefits Opportunity to work on production infrastructure handling 1 trillion + daily requests. Work within a team of senior engineers with direct impact on the platform's architecture. Choice between a fully remote schedule or a hybrid format from the office in Budva, Montenegro. Stable monthly payments in USD via international B2B contracts.