Balazs Kollar, Developer in Sarasota, FL, United States
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Balazs Kollar

Verified Expert  in Engineering

Software Developer

Sarasota, FL, United States
Toptal Member Since
September 30, 2021

Balazs has over 10 years of hands-on development experience building greenfield Java solutions for the financial sector in FX spot and fixed income segments for Tier 2 investment banks. He also holds an MBA and has worked both in offshore and onshore locations in client-facing roles. Balazs is passionate about finding simple solutions to complex problems.


Go, SQL Server 2015, CockroachDB, Temporal, Node.js, Gorm, Microservices, APIs...
Real Estate Development, Residential Real Estate, Agile Project Management
EPAM Systems
Hadoop, Tableau, PySpark, Apache Sqoop, Team Leadership, Agile Leadership...




Preferred Environment

Test-driven Development (TDD), FIX Protocol, Git, Low Latency, Go, Java, IntelliJ IDEA, Agile Leadership, Amazon Web Services (AWS)

The most amazing...

...project I've had was to build a global FX algorithmic order management solution for a Tier 2 investment bank.

Work Experience

Senior Java Developer

2021 - 2023
  • Developed a range of new microservices on Go/Gorm/CockroachDB/SQL Server stack: integrations to Equifax, Experian, TransUnion, and LexisNexis APIs. Built Temporal workflows to serve business-critical processes like credit alert notifications.
  • Mentored team members to ensure they brought their best to the project.
  • Led the development effort by creating a story breakdown and coordinating with other squads. Took part in L2 production support.
Technologies: Go, SQL Server 2015, CockroachDB, Temporal, Node.js, Gorm, Microservices, APIs, GitLab, REST APIs, Cadence, Distributed Systems, JavaScript

Project Owner

2020 - 2021
  • Worked on setting up a private venture in real estate development. I did thorough business planning, negotiating with potential subcontractors.
  • Coordinated work of architects to develop detailed architectural, statics, electrical, heating, plumbing, fire protection plans.
  • Worked with the local construction authority to get a building permit and with electrical, natural gas, water, and sewage utilities to acquire permits for construction.
Technologies: Real Estate Development, Residential Real Estate, Agile Project Management

Delivery Manager

2018 - 2019
EPAM Systems
  • Managed a team that developed a data lake serving a reporting platform for wealth management client representatives.
  • Drove talent acquisition processes end-to-end from interviewing through job offers. Was responsible for onboarding new members to the project.
  • Established development and release processes and mentored developers. I performed code reviews and provided delivery forecasts.
  • Handled the contract renewal process with our customer. Also, I provided PnL forecasts for the account manager.
  • Created proposals for new engagements, including consulting work.
  • Served as a consultant and performed interviews with senior management of the real estate business unit of the bank in order to document how they use data through the workflow and how that data could be reused and made searchable as comparables.
Technologies: Hadoop, Tableau, PySpark, Apache Sqoop, Team Leadership, Agile Leadership, Agile Project Management, IT Management

Senior Staffing Manager for Financial Services Business Unit

2017 - 2018
EPAM Systems
  • Covered staffing of the EU region of the Financial Services Business Unit. Prepared staffing plans for new engagements that enabled account managers to refine their client proposals.
  • Helped in resolving staffing bottlenecks in running projects.
  • Mediated between account managers and location staffing coordinators to ensure the right people are proposed and assigned to opportunities.
Technologies: Staffing, IT Management

Lead Software Engineer

2015 - 2016
EPAM Systems
  • Took part in maintaining the central fixed-income pricing bus of a Tier 2 investment bank. We transitioned the system to a new strategic market data streaming platform while also took care of production support tasks.
  • Acted as a team lead and was responsible for the coordination with the onshore team and their performance.
  • Enhanced our agile processes, introducing retrospective meetings, and following up on action items.
Technologies: Fixed Income, Live Pricing, Pricing Models, Java, Sybase, Multithreading, Team Leadership, Agile Leadership, Jira, APIs, JMS, JVM, IT Management

Lead Software Engineer

2012 - 2015
EPAM Systems
  • Built a greenfield globally distributed algorithmic FX order management system for a Tier 2 investment bank. I personally implemented the FIX protocol integration with execution venues, and also a FIX message store on a distributed Infinispan cache.
  • Provided technical guidance and controlled the activities of my team. I took part in designing the application and supervise the code quality via code reviews.
  • Kept close focus on understanding customer expectations, priorities while being flexible in reacting to their changing needs. Also, I refined user stories, performed code reviews.
  • Pre-screened candidates for filling open positions. I performed dozens of technicals interviews over the years.
Technologies: Java 8, TIBCO Enterprise Message Service (EMS), IBM MQ, Multithreading, Hibernate, Gemfire, JBoss Infinispan, Apache Maven, Low Latency, Team Leadership, Agile Leadership, JUnit, Jira, Crucible, Confluence, GitLab, TeamCity, Bamboo, APIs, Microservices, JMS, JVM, Distributed Systems, Agile Project Management

Senior Java Developer

2010 - 2012
Synergon System Integrator
  • Planned and developed a pilot solution for managing the lifecycle of XAdES PKI digital signatures using Spring Batch, Hibernate, and OpenMQ.
  • Extended the functionality of the company’s own filing system product to be used by the Hungarian disaster protection.
  • Designed and implemented Apache ActiveMQ and Camel-based integration solutions towards SharePoint and EMC Captiva. Also, I introduced Spring Batch for handling all nightly jobs.
Technologies: Java 7, Cryptography, PKI, Digital Signatures, SmartClient, ActiveMQ, Spring Batch, Spring, Apache Maven, Hibernate, RDBMS, JUnit, JavaScript, TeamCity, JSON, APIs, JMS, JVM, Distributed Systems

Senior Java Developer

2008 - 2010
Asseco Central Europe
  • Had a key role in building a full GWT-based rich web application for consumer loan origination. I created the initial system frame by plumbing all necessary technologies from persistence, services, CXF web services to the GWT-based presentation layer.
  • Designed and implemented a custom GWT-based, framework built on Ext GWT, for handling page flow, window management, forms, data binding, translations, and server-client RPC communication for the front-end and back-end presentation layer.
  • Integrated JBoss jBPM WorkFlow engine into the system. I designed and implemented the credit application workflow based on the client's existing business process.
  • Developed and performed the load test of the system using JMeter, JProfiler, and Eclipse Memory Analyzer. Also, I resolved the bottlenecks and other performance problems found.
Technologies: Spring, GWT, GWT-Ext, jBPM, Apache Maven, Jenkins, CXF, AspectJ, Java, Hibernate, RDBMS, Oracle, JUnit, Subversion (SVN), APIs, JVM

Java Developer

2006 - 2007
  • Developed a desktop smartcard management utility that could initialize G&D StarCOS smartcards, generate on-chip private keys, and upload PKI certificates.
  • Created Windows installer and documentation for the software package.
  • Built remote smartcard management Jakarta EE server component.
Technologies: PKI, Cryptography, BouncyCastle, Java, Smartcard, Swing, Windows Installer, PKCS #11, OpenCard, InstallShield, Subversion (SVN), JVM

FX Algo Order Management System for UBS
A Java-based order management system for FX Algo orders. I was a back-end developer on this greenfield project implementing essential architectural elements of the system, including FIX protocol integration to execution venues.

Consumer Loan Origination Solution for Sofinco Group

I took a key role in building a GWT-based rich web application and back end handling the full process of consumer loan origination. Also, I was responsible for building the three-tiered architecture such as service layer exposed via CXF, GWT presentation layer, and also for modeling the loan workflow with jBPM.
2016 - 2017

Master's Degree in Business Administration

CEU Business School - Budapest, Hungary

2006 - 2007

Master's Degree in Banking and Finance IT Engineer

Budapest University of Technology and Economics - Budapest, Hungary

2001 - 2006

Master's Degree in Information Technology

Budapest University of Technology and Economics - Budapest, Hungary


JMS, REST APIs, JPA 2, Windows API, PySpark, BouncyCastle, PKCS #11, Node.js


Apache Maven, Git, Jenkins, GitLab, TIBCO Enterprise Message Service (EMS), Apache ZooKeeper, TeamCity, Bamboo, JProfiler, Tableau, Apache Sqoop, IBM MQ, Windows Installer, InstallShield, ActiveMQ, Apache Tomcat, Dozer, Jira, Crucible, Confluence, Subversion (SVN), IntelliJ IDEA


Spring, Hibernate, Apache CXF, GWT, Spring Boot, jBPM, GWT-Ext, Hadoop, CXF, Swing, SmartClient, Spring Batch, JUnit, Gorm


Agile Project Management, Scrum, REST, Test-driven Development (TDD), Design Thinking, Microservices


Java 8, Java, Java 7, Go, GraphQL, AspectJ, SQL, C++, JavaScript


Java EE, JVM, Oracle, Amazon Web Services (AWS)


RDBMS, MongoDB, JBoss Infinispan, Sybase, JSON, CockroachDB

Industry Expertise



Multithreading, FIX Protocol, PKI, Team Leadership, Agile Leadership, Domain-driven Design (DDD), Distributed Systems, Low Latency, Architecture, Staffing, CI/CD Pipelines, APIs, Tempora, IT Management, Gemfire, Order Management, Fixed Income, FX, Negotiation, Cost Accounting, Innovation, Marketing Mix, Entrepreneurship, Organizational Design, Finance, Strategy, IT Project Management, Investment Banking, Algorithms, Cryptography, Networking, Live Pricing, Pricing Models, Digital Signatures, Smartcard, OpenCard, Real Estate Development, Residential Real Estate, SQL Server 2015, Temporal, Cadence

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