Dusan Simonovic, Software Developer in Belgrade, Serbia
Dusan Simonovic

Software Developer in Belgrade, Serbia

Member since February 8, 2017
Dusan is a full-stack Java and React developer with twelve years of software development experience. He's worked on several large projects, including Price2Spy, a tool for data web scraping for tracking competitor pricing on online shops, a social marketing tool for Adobe Marketing Cloud, and an in-flight connectivity tool for a leading airline connectivity provider, and API integrations for a SaaS analytics provider.
Dusan is now available for hire




Belgrade, Serbia



Preferred Environment

Maven, Gradle, Windows, MacOS, Git, IntelliJ

The most amazing...

...project I've worked on is a huge social network marketing platform for Adobe Marketing Cloud.


  • Senior Full-stack Developer

    2019 - 2019
    Patagonia Insurance, LLC
    • Built a React-based front-end app from existing designs.
    • Built a Java/Spring back end for our web platform.
    • Implemented a full CI/CD pipeline.
    • Set up AWS infrastructure for front end, back end, email sending, and more.
    • Integrated our web platform with various third-party APIs (e.g., TrustedForm, LeadID, Google Tag Manager and Google Analytics, or Maxminds).
    Technologies: Spring, Java, React
  • Senior Full-stack Developer

    2018 - 2019
    U Group (former Bytecubed) (via Toptal)
    • Architected the Kafka backbone.
    • Made key contributions to module integration architecture through the Kafka backbone.
    • Developed back-end features in Java Spring and front ends in Angular and React.
    Technologies: Angular, React, Apache Kafka, Java, Spring
  • Senior Java Engineer

    2018 - 2018
    Datasnap, Inc. (via Toptal)
    • Implemented a data processing pipeline for processing trading events from a NASDAQ trading platform.
    • Achieved very high throughput and very low latency in processing messages. An amount of 10GB of data (360 millions of trading events) is being processed (including data transformation, aggregation, and joins) in less than 20 minutes. End to end latency at the end of project was below 1 millisecond.
    • Implemented a pluggable model to support different implementations for input reading and output format.
    • Maintained full integration testing in a Docker container.
    • Built a full CI/CD pipeline.
    Technologies: Continuous Deployment, Continuous Integration (CI), Apache Kafka, Java
  • Senior Java Developer

    2017 - 2018
    MetaSaas (via Toptal)
    • Worked on integrations with various SaaS vendors using mostly REST.
    • Reviewed code and handled approvals for other developers.
    • Mentored and helped new developers start with integrations.
    • Developed an expenses matching mechanism using Expensify API and Elasticsearch.
    • Helped create integration testing for new integrations.
    Technologies: MyBatis, Elasticsearch, OAuth, JSON Web Tokens (JWT), REST, Java
  • Senior Java Developer

    2017 - 2018
    Gogo, LLC
    • Led the development of a back-end tool used by airlines to track usage of the GogoAir in-flight entertainment system in real time.
    • Developed microservices (Spring REST services—Spring Cloud, Netflix OSS, AWS).
    • Built a deployment process (Netflix OSS, AWS, Spring Cloud).
    • Refactored some of the legacy code and migrated data from a data center to the cloud.
    • Enhanced security in an existing system.
    Technologies: Amazon Web Services (AWS), Spring Cloud, Java
  • Senior Java Engineer/Scrum Master

    2015 - 2017
    Endava d.o.o.
    • Led the remote element of a technical team.
    • Developed core services for the Adobe social media marketing platform.
    • Built a link shortening service to be used across the platform.
    • Created a label management service for managing content tags/labels.
    • Developed an asset service to store user assets to Amazon S3.
    • Presented at "Pass it on" sessions to help other members of the company to gain knowledge.
    Technologies: Agile, Scrum, Git, MySQL, HBase, JDBI, Jersey, REST, Dropwizard, Java
  • Web Developer, System Administrator

    2010 - 2015
    Webcentric d.o.o.
    • Contributed to the development of a tool for monitoring competitor prices on online shops.
    • Handled the deployment lifecycle of the application.
    • Maintained all application environments from development to production.
    • Architected a huge MariaDB Galera cluster.
    • Mentored juniors and worked on developing them as professionals.
    • Set up and maintained a CI environment.
    • Developed full-stack features (Java back-end, HTML/CSS/JS on UI).
    Technologies: JPPF, Subversion (SVN), Spring, MariaDB, MyBatis, Java


  • Cisco Certified Network Associate

    Cisco official certification program (CCNA).

  • Price2Spy

    A tool used by web shop owners to monitor their competitors. By using this tool, they get notified about all the changes that happen on their competitor's shops, so they can react accordingly with price or any other adjustments.

  • Adobe Social - Core Services

    This tool is a huge set of modules that helps enterprise clients set up and maintain their social media marketing campaigns. This project was developed for a world-leading IT company, and its clients are some of the world's top companies.

  • MetaSaas Platform

    MetaSaas is the best SaaS management tool for medium and large businesses. Manage SaaS vendors, reduce SaaS spend, and manage cloud applications from a single and easy to use dashboard.

    As part of the MetaSaas team, my role was to develop more complicated integrations to SaaS vendors and to do code reviews and quality checks for other developers. This involved using REST, OAuth, JWT, and more.

  • Gogo, Ltd.

    Gogo is a leading in-flight connectivity and entertainment provider. As a member of development team in Belgrade, I was involved in back-end and front-end development of the cloud solution for Airlines to track usage of the system in airplanes. This involved back-end development (Spring cloud, Netflix OSS) and UI (React and Redux).

  • Datasnap JTrain

    A high-volume/low-latency data processing tool that processes events from the NASDAQ trading platform and produces output. This tool involved data lookup (joins), aggregation, and data transformation.

  • EinsteinMedicare

    A web platform used to connect insurance buyers with insurance companies.

  • Get Started With Microservices: A Dropwizard Tutorial (Publication)
    Dropwizard allows developers to quickly bootstrap their projects and package applications as easily deployable standalone services. It also happens to be relatively simple to use and implement. In this tutorial, Toptal Freelance Software Engineer Dusan Simonovic will introduce you to Dropwizard and demonstrate how you can use this powerful framework to create RESTful web services with ease.


  • Languages

    SQL, Java, TypeScript
  • Frameworks

    Spring, OAuth 2, Dropwizard, JUnit, Angular, Spring Boot, Jersey, JSON Web Tokens (JWT)
  • Libraries/APIs

    React, Apache Lucene, JDBI, MyBatis
  • Tools

    RabbitMQ, Solr, IntelliJ, Git, Gradle, Maven, Subversion (SVN)
  • Paradigms

    Reactive Programming, Microservices, Back-end Architecture, Continuous Delivery (CD), Scrum, Test-driven Development (TDD), Continuous Integration (CI), REST, Agile, Continuous Deployment
  • Platforms

    Amazon Web Services (AWS), Docker, Apache Kafka, MacOS, Ubuntu, Windows
  • Storage

    MongoDB, Amazon DynamoDB, Microsoft SQL Server, H2, Redis, MySQL, MariaDB, Elasticsearch, HBase, Cassandra
  • Other

    Netflix OSS, Networks, JPPF, Spring Cloud, OAuth


  • Cisco Certified Network Associate in Computer Networking
    2009 - 2009
    Cisco Net Academy - FTN Rao, Novi Sad Serbia
  • Master's Degree in Microcomputer Electronics
    2000 - 2006
    Faculty of Technical Sciences - Novi Sad


  • AWS Certified Solutions Architect — Associate
    DECEMBER 2022 - DECEMBER 2025
    Amazon Web Services

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