Dusan Simonovic, Developer in Belgrade, Serbia
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Dusan Simonovic

Verified Expert  in Engineering

Software Developer

Belgrade, Serbia
Toptal Member Since
February 8, 2017

Dusan is a full-stack Java and React developer with 13 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.



Preferred Environment

Apache Maven, Gradle, Windows, MacOS, Git, IntelliJ IDEA

The most amazing...

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

Work Experience

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, SaaS Operations (SaaSOps)

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).


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.


A web platform used to connect insurance buyers with insurance companies.
2009 - 2009

Cisco Certified Network Associate in Computer Networking

Cisco Net Academy - FTN Rao, Novi Sad Serbia

2000 - 2006

Master's Degree in Microcomputer Electronics

Faculty of Technical Sciences - Novi Sad


AWS Certified Solutions Architect — Associate

Amazon Web Services


React, Apache Lucene, JDBI, MyBatis


RabbitMQ, Solr, IntelliJ IDEA, Git, Gradle, Apache Maven, Subversion (SVN)


Spring, OAuth 2, Dropwizard, JUnit, Angular, Spring Boot, Jersey, JSON Web Tokens (JWT)


SQL, Java, TypeScript


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


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


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


Netflix OSS, Networks, JPPF, Spring Cloud, OAuth, SaaS Operations (SaaSOps)

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