About Me

calendar Jul 10, 2022 · 4 min read  ·

What I Do

I'm Marko Milenkovic, a Senior Java Developer & Team Lead with 10+ years of professional experience in backend development and 15+ years in software development. Based in Nis, Serbia.

Specialist in REST API design, platform migrations, CI/CD engineering, and application security across enterprise fintech products involving large-scale data processing. Focused on sharing knowledge and helping Java developers optimize their work — writing clean, secure, and performant code.

What I Write About

This site is where I document what I actually learn and measure:

  • Performance benchmarks — real numbers, not vibes (see the Fastest Way To Insert Data in MS SQL series)
  • JPA/Hibernate & databases — the pitfalls that cost hours in production
  • Testing — JUnit 5, parallelization, test-suite speed
  • Short lessons — quick notes land in TIL

Runnable code for posts lives in blog-examples.

Elsewhere

What I'm Doing Now

Last updated: October 2026

Building an agentic development framework

My main focus right now is building an agentic development framework on top of Devin — the one powering real work on a 4,000-file Spring Boot codebase. It's a measurement-first setup: context budgets, specialist checkpoints, read-only subagents, and an eval harness that treats prompt changes like code changes.

  • Writing the 11-part Agentic Development series on patterns that actually paid off
  • Running the eval harness against every PR touching skills or rules — three real regressions caught before rollout
  • Experimenting with cheaper-model subagents for exploration tasks (5x cost reduction, no accuracy loss on measured research questions)
  • Thinking about the next cliff: what's the shape of a 50x-cheaper tool-restricted agent?

Day job

  • Java backend engineering on multi-tenant SQL Server workloads — Hibernate 6, Spring Boot 3, JDBC Bulk API
  • Performance tuning: the Fastest MS SQL Inserts series grew out of a real bottleneck I shipped a fix for
  • Code review on security remediation and database migrations

Website

  • Keeping this site measured and honest: SEO, OG cards, structured data, image budgets
  • Experimenting with Instagram-style like hearts instead of opacity dimming — small UX wins that compound

Reading & exploring

  • Java virtual threads — where they actually help (hint: not everywhere; the hype is uneven)
  • Hibernate 6 performance pitfalls — the next post series
  • The TIL feed is where loose notes and short lessons land before they become posts

Inspired by nownownow.com — a page that answers "what are you up to these days?"

CV

Download the full PDF: Marko_Milenkovic_CV.pdf

Employment History

Senior Java Developer & Team Lead — Investment Cafe

Badin Soft (2018–2024) → Wiser Technologies (2024–Present) 2018 — Present

Team lead and core maintainer of the Investment Cafe platform at BlackRock (formerly eFront) — a multi-tenant document management and investor communication system serving BlackRock's alternative investments clients globally.

  • Led a development team, coordinating work and guiding team members
  • Built the REST API layer from scratch: FundInvestor, FundFamily, and DocumentTypes services
  • Designed and implemented the MFA/TOTP authentication system — full lifecycle
  • Created the Cloud Store POC for cloud-native S3 storage
  • Led the Spring Boot 3 migration (148 commits, 2,483 files): javax→Jakarta, Hibernate 5→6, OpenAPI 3
  • Built the IC Full Deployment Pipeline (Azure Pipelines + Terraform + AWS EBS) with Blue-Green deployments
  • Spearheaded TVAS security hardening (58 commits): SQL injection, SSRF, path traversal, AES/GCM encryption
  • Delivered major performance improvements: Contact Import bottleneck, materialized view redesign, Document Search
  • Drove the Flash → Spring Boot/React migration under tight deadlines
  • Designed and implemented the Excel import/export module end-to-end
  • Improved the mailing system: automated D5 emails, email archive with BCC, PII masking
  • Contributed across 6 product areas beyond IC: CPS Integration Services, Asset Servicer Portal, CRM Platform, Insight Core, Invest

Tech: Java 17, Spring Boot 3, Hibernate 6, Jakarta EE, MSSQL, Liquibase, OAuth2, Docker, Terraform, AWS EBS, TomEE 10, OpenAPI 3, CyberArk, SonarQube, Veracode, Azure Pipelines, React, .NET/C#

Senior Java Developer & Tech Lead — CREALOGIX E-Banking

Badin Soft | 2017–2018

E-banking application for major Swiss banks (TKB, BKB, AKB). Maintained version 2.0 across 3 major releases.

Tech: Java, Spring, Oracle DB, Git, Bitbucket

Senior Java Developer — Transactor HQ

Badin Soft | 2014–2017

Three-layer fintech application (Oracle, Java Spring/MyBatis/Jersey API, Angular). Designed and developed secure, high-performance RESTful API services.

Tech: Java, Spring Boot, MyBatis, Jersey, Oracle DB, Angular

Freelance Developer

December 2011 — April 2014

Various projects in Java: Swing, GWT, JSP, JSF, Android, Apache CXF, Spring, REST.

Education

  • Master's Degree — Computer Science, University of Nis (2011–2016)
  • Bachelor's Degree — Computer Science, University of Nis (2007–2011)

Technical Skills

Languages: Java, SQL, PL/SQL, JavaScript, C#/.NET, Python, C/C++

Frameworks: Spring (Core, MVC, Boot, Security, Batch, Cloud, WebFlux), Hibernate, MyBatis, Jakarta EE, EJB, OAuth2

Web: REST, SOAP, OpenAPI 3, gRPC, Microservices, Kafka, React, Angular

Databases: MS SQL Server, Oracle DB, PostgreSQL, H2, Azure Cosmos DB, Liquibase

DevOps: Docker, Terraform, Azure Pipelines, GitHub Actions, Jenkins, AWS (EBS, S3, CloudWatch), SonarQube, Veracode

Tools: Git, Maven, IntelliJ IDEA, JMeter, Postman, Splunk, CyberArk

Languages

  • Serbian — Native
  • English — Full Professional Proficiency