Production Java & Spring
Backend systems built with clear service boundaries, secure APIs, maintainable domain models, and disciplined testing.
- Spring Boot / MVC
- Security / Data / Cloud
- Hibernate / JPA
Senior software engineer · Backend systems · Belgrade, Serbia
Software engineering for complex backend products.
I help product teams design, build, and operate scalable backend systems, APIs, and integrations with Java, Spring Boot, PostgreSQL, and AWS.
BACKEND PLATFORM / 01 LIVE SYSTEM
INGRESSAPI GatewayLoad balancing · Traffic routing
APPLICATION SERVICESJava / Spring BootAPIs · Business logic
SECURITYAUTH SERVERDISCOVERYCONSUL
PERSISTENCEPostgreSQLTransactions · Reporting
INTEGRATIONEvents & APIsQueues · External systems
6+years building
Java / Spring systems
Java / Spring systems
100+of APIs designed
and delivered
and delivered
50+technical interviews
conducted
conducted
ARCHITECTURE · DELIVERY
PRODUCTION OWNERSHIP
SOLUTIONS
Software solutions for
companies and individuals.
I work with companies, product teams, and individuals to design and deliver software that matches their goals, budget, and stage of development. My services range from complete SaaS products, backend platforms, integrations, and internal tools to business websites and focused personal websites. Each engagement includes clear scope, practical technology choices, responsive implementation, and support through delivery.
SAAS PRODUCTS
Architecture, backend systems, APIs, data, cloud infrastructure, and product delivery.
BUSINESS SOFTWARE
Integrations, internal tools, workflow systems, payments, and operational improvements.
WEBSITES
Professional websites for businesses, independent professionals, and personal use.
01 / EXPERTISE
Backend engineering from
architecture to production.
My foundation is production backend engineering: architecture, implementation, data, testing, rollout, reliability, and the knowledge transfer that keeps teams moving.
Distributed backend systems
REST APIs, asynchronous workflows, idempotency, circuit breakers, observability, and failure handling designed for operational pressure.
- REST / SOAP / WebSockets
- SQS / SNS
- Resilience4j
PostgreSQL & data engineering
Complex SQL, indexes, partitioning, JSONB, query plan analysis, connection tuning, and migrations involving millions of records.
- Query planning
- ETL / migrations
- Performance tuning
02 / TECHNICAL DEPTH
Technical expertise across
the backend stack.
The tools behind the work, from application code and database internals to tests, delivery infrastructure, and production operations.
Backend application engineering
Java · Spring Boot · Spring MVC · Spring Security · Spring Data · Spring Cloud · Hibernate / JPA · Maven · Gradle
API design and integration
REST · SOAP · WebSockets · OpenAPI · Authentication · Authorization · Versioning · Pagination · Idempotency
Data modeling and performance
SQL · JSONB · Indexing · Partitioning · Materialized views · Query plans · Pool tuning · Redis · MongoDB
Automated testing
JUnit · Mockito · AssertJ · Testcontainers · WireMock · Integration testing · Contract testing
Cloud infrastructure and operations
AWS · Docker · Kubernetes · Helm · Jenkins · Prometheus · Grafana · HPA · KEDA
Applied AI systems
Bedrock · Claude · Nova · Model routing · Structured outputs · Tool calling · Guardrails · Evaluation · NL2SQL
03 / SELECTED WORK
Selected backend and
platform work.
Production systems I designed, implemented, and supported.
Electronic prescribing platform
Built the Java/Spring backend from zero and owned architecture, Surescripts and FDB integration, certification, rollout, and support.
- Java
- Spring Boot
- PostgreSQL
- Surescripts
Central AI platform
A production platform layer for prompt and model configuration, routing and fallback, request logging, plus token, cost, and latency tracking.
- Spring Boot
- Bedrock
- Claude / Nova
- Observability
Square payment processing
Built a Java/Spring payment system from scratch, covering Square authentication, webhooks, failure handling, and production rollout.
- Java
- Spring Boot
- Square
- Webhooks
Agentic data workflow
An agentic data workflow combining NL2SQL, intent routing, tool execution, permissions, guardrails, and conversation history.
- Python
- FastAPI
- NL2SQL
04 / EXPERIENCE
Six years of increasing responsibility
in the healthcare industry.
2019Junior Software EngineerFOUNDATIONS
2020Software EngineerOWNERSHIP
2024 TO PRESENTSenior Software EngineerBACKEND SYSTEMS & DELIVERY
Backend ownership from architecture and implementation to release, production support, and team knowledge transfer.
Engineering scope
- Backendarchitecture and system design
- 50+technical interviews conducted
- Productiondeployment, monitoring and incident resolution
BELGRADE / SERBIA44.7866° N, 20.4489° E
05 / ABOUT
Senior software engineer
with complete ownership.
I’m Aleksandar, a senior software engineer with deep Java and Spring experience, focused on critical business backend products and the systems that keep them reliable.
I’ve spent more than six years owning Java/Spring software from the first technical decision to the incident review. I care about clear interfaces, measurable reliability, and pragmatic architecture that earns its complexity.
AI is an additional tool in that engineering practice. It is not a replacement for it. I’m completing a Master’s in Computer Science at the University of Belgrade, researching scalable AI applications with Kubernetes and event based systems.
06 / CONTACT
Tell me what you
need to build.
Share a short outline of your project, its current stage, and the expertise you need. I will reply with relevant questions and a practical next step.