Ajax Systems, an international tech company and the largest manufacturer of security systems in Europe. We are looking for a new team member to join our System devisions as a Senior Java Developer. The System Division is responsible for building and developing the Ajax software ecosystem. The team develops and maintains OS Malevich and the Video Management System, builds scalable cloud infrastructure, and creates client applications for multiple platforms, ensuring that all system components work together as a unified ecosystem. The division works with Java, Kotlin, Swift, C, C++, and Python. It includes embedded, cloud, mobile, and desktop engineers who ensure the stable operation of Ajax as a single digital platform. RESPONSIBILITIES: Core Development: Design and implement core backend services and data pipelines Write clean, readable, and maintainable code Develop services for the b2b product line Architecture & Documentation: Actively participate in developing and improving architecture Document architectural decisions and operational knowledge for successful deployment and service operations Quality Assurance: Ensure appropriate test coverage with unit and integration testing Focus on performance and cost efficiency for areas of responsibility Follow best practices in software design and development and promote them within the team Operations & Monitoring: Ensure reliable alerting, dashboards, and runbooks for production services Debug production issues, analyze complex cases, and conduct investigations Collaboration & Culture: Work smoothly in a technical culture with testing, CD, and DevOps Collaborate within the team and with other engineering teams to develop new features and products according to business needs REQUIREMENTS: Java: 3+ years of professional backend development in enterprise environment Kotlin: Knowledge and practical work experience Java Concurrency: Strong understanding and practical application experience Understanding of SOA, microservice, and event-driven architecture Cloud development principles with practical AWS experience Ability to scale and ensure high availability of loaded systems REQUIRED: Any NoSQL database Any message broker Enterprise-grade stack (messaging brokers, in-memory storages, NoSQL, key-value databases) Docker and Kubernetes (containerized applications) Git, Gradle, Jenkins NICE TO HAVE: Redis, Netty, Akka, gRPC, Project Reactor, NATS, Kafka. MongoDB Strong knowledge of unit testing and automated test paradigms WE OFFER: The opportunity to suggest and implement your own ideas that directly influence the product and its mass production A place in a fast-growing company with a motivated and professional team Competitive salary Medical insurance English classes The opportunity to participate in Ajax’s internal beta-testing program for security systems  Discounts from partner companies Discounts on Ajax products Ajax Systems is a Ukrainian success story that has grown into a global product. Ajax devices are trusted by more than 4.5 million end users and 330,000 PRO users in over 180 countries. The company provides comprehensive solutions to protect residential and commercial properties of all sizes. Today, Ajax portfolio includes 280 devices for intrusion protection, video surveillance, fire safety, and comfort and automation.