Senior Java Developer

Senior Java Developer at IT-One. Design platform architecture, REST API, work with microservices, PostgreSQL, Kafka, Redis.

Design and develop platform architecture and domain model: requests, billing, payments, personal accounts, access control systems. Make key technical decisions, evaluate trade-offs, and implement them. Develop and maintain business logic of main REST API and related services. Work with multi-tenant architecture (schema per tenant), ensuring data isolation and predictable behavior under load. Design and optimize data access layer (Hibernate/JPA + jOOQ), complex and high-performance queries, schema evolution (Liquibase). Develop asynchronous scenarios and event processing (Kafka), caching (Redis/Redisson), file storage (S3/MinIO). Design and maintain integrations with external systems (payment gateways, access control, notification providers). Set testing and code quality standards: unit and integration tests (JUnit 5, Testcontainers), Checkstyle, unified code style. Conduct code reviews, mentor middle/junior developers, participate in hiring and technical onboarding. Identify and eliminate performance and reliability bottlenecks; participate in incident analysis.

Commercial experience in Java development from 5 years, confident knowledge of modern versions (17+). Expert knowledge of Spring ecosystem (Spring Boot, Spring MVC, Spring Data, Spring Security). Deep knowledge of PostgreSQL: schema design, writing and optimizing SQL, transactions, isolation levels, indexes, query plans. Strong experience with ORM (Hibernate/JPA) — understanding internal structure, typical problems (N+1, cache, lazy/eager, dirty checking) and solutions. Experience in designing and operating production systems: scaling, fault tolerance, observability. Proficient in asynchronous messaging (Kafka or similar) and caching (Redis or similar). Experience in building and versioning REST API, documentation (OpenAPI/Swagger). Mature engineering culture: automated testing, code review, CI/CD, Git, multi-module projects (Maven). Ability to lead a task from requirements discussion to deployment. Nice to have: multi-tenant systems / SaaS architecture, jOOQ, Liquibase, MapStruct, Lombok, state machines, Kotlin, Testcontainers, MinIO/S3, Keycloak/OIDC, JWT, Docker, GitLab CI, monitoring (Prometheus, Jaeger/Zipkin).