Mile Kostoski is a Senior Java Backend Developer based in Skopje, North Macedonia, with 10+ years of experience building enterprise applications, distributed systems and cloud-native backend services.

Portfolio — Mile Kostoski · LinkedIn — Mile Kostoski · GitHub — Mile Kostoski (@m1l3)

I specialize in Java and the Spring ecosystem, with a strong focus on backend architecture, microservices, APIs, relational data, distributed workflows, cloud infrastructure and maintainable enterprise software.

My production work is primarily in private enterprise repositories, while this GitHub profile contains public projects, experiments and technical examples that represent the technologies and engineering practices I use professionally.

• Java 11 / 17 / 21
• Spring Boot and the Spring ecosystem
• Microservices and distributed systems
• REST APIs and service integrations
• PostgreSQL, JPA, Hibernate and jOOQ
• RabbitMQ and event-driven workflows
• AWS, Docker and Kubernetes
• Keycloak and authentication / authorization
• Gradle and Maven
• JUnit, Mockito and automated testing
• CI/CD with GitHub Actions, Jenkins and TeamCity

I enjoy designing resilient backend services, untangling complex business logic, defining clean API contracts, improving performance, modernizing mature systems and building software that remains understandable and maintainable over time.

01  Prefer clarity over cleverness
02  Make failure modes visible
03  Keep business rules explicit
04  Optimize after measuring
05  Design APIs as long-term contracts
06  Treat tests as executable documentation
07  Automate repetitive work
08  Leave the codebase better than you found it

Complex workflow orchestration, publication lifecycles, subscriptions, pricing rules, permissions, document generation, integrations and modernization of mature applications.

Spring Boot services, asynchronous processing, messaging, Docker, Kubernetes, AWS infrastructure, observability and production troubleshooting.

Keycloak extensions, multitenancy, SSO, authentication flows, user discovery and secure backend integration.

Caching, database query optimization, legacy service stabilization, infrastructure investigation and incremental redesign.

Alongside Java and system design, I am exploring AI-assisted software development, coding agents, RAG, MCP, automated code review and engineering workflows that reduce repetitive work without sacrificing correctness or ownership.

Public GitHub statistics represent only a small part of my engineering work because most of my professional code is in private enterprise repositories.

• Website: Mile Kostoski — Senior Java Backend Developer
• LinkedIn: Mile Kostoski
• GitHub: Mile Kostoski (@m1l3)

Mile Kostoski · Senior Java Backend Developer · Java · Spring Boot · Microservices · AWS · Kubernetes · PostgreSQL