Mark Kercso, Developer in London, United Kingdom
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Mark Kercso

Verified Expert  in Engineering

Software Developer

London, United Kingdom
Toptal Member Since
October 16, 2016

Mark has six years of professional development experience—mostly in the C++, Perl, JavaScript, and Ruby. He has worked on a wide range of projects from telecommunications through game development and computer security to static analysis.


Amazon Web Services (AWS), WebSockets, Spring Boot, MongoDB, Kubernetes...
Programming Research
Ruby, Python, C++, C, Perl
Amazon Web Services (AWS), Low Latency, Docker, Git, Linux, JavaScript...




Preferred Environment

Chrome, Git, Vim Text Editor, Komodo IDE, Visual Studio

The most amazing...

...product I've worked on so far was a complex threat analysis tool which could identify malicious patterns via cross-analyzing the results of other products.

Work Experience

Senior Full-stack Developer

2018 - PRESENT
  • Developed a complex web application allowing customers to compare various service providers and follow the whole lifecycle of their shipment from creation to delivery.
  • Had a major role in transitioning the monolithic back-end of the application to microservices architecture.
  • Took part in the project from before MVP phase to production-grade enterprise application.
Technologies: Amazon Web Services (AWS), WebSockets, Spring Boot, MongoDB, Kubernetes, MERN Stack, MongoDB Shell, MongoDB Atlas, Spring Data MongoDB, Amazon EC2, Amazon Elastic Container Registry (ECR), AWS ELB, AWS SDK, Amazon Elastic Container Service (Amazon ECS), Amazon S3 (AWS S3), REST, REST APIs, Docker, Microservices, Linux, IntelliJ IDEA, Java 11, React, JavaScript, Node.js, Spring, Google Cloud Platform (GCP)

Software Engineer

2016 - 2016
Programming Research
  • Wrote a secondary analysis code that checks for C++ errors.
  • Assembled compliance module packages for various coding standards.
  • Maintained, updated, and extended a compliance module generator written in C++.
Technologies: Ruby, Python, C++, C, Perl

Software Engineer

2014 - 2016
  • Refactored and upgraded a complex cross-module analysis tool for threat research written in AngularJS, Elasticsearch, and JRuby.
  • Participated in the 24/7 standby on-call rotation to react to critical system issues.
  • Maintained and extended a web portal written in Perl (Mason) used internally.
  • Created and maintained multiple lightweight REST API services written in Ruby (Sinatra), Perl, and Node.js.
  • Made a reusable load balancing and throttling service with different consolidation mechanisms to soothe the load at peak times and prevent service overload.
  • Developed several ETL solutions in Perl and Ruby in compliance with the company's SOA model.
  • Developed and maintained mission-critical systems in the threat research lab.
Technologies: Amazon Web Services (AWS), Low Latency, Docker, Git, Linux, JavaScript, Elasticsearch, AngularJS, Python, Perl, Sinatra, Ruby on Rails (RoR), Ruby

R&D Programmer

2013 - 2014
  • Maintained the internally used game engine for mobile applications.
  • Wrote cross-platform C++ code for the game engine.
  • Participated in the development of the real-time collaborative feature of the game engine.
  • Created new custom OpenGL UI controls from scratch for the mobile game engine.
Technologies: OpenGL, C++

Software Developer

2012 - 2013
  • Developed a plugin for Microsoft CRM to integrate with Avaya systems.
  • Developed an SMS sending/processing service written in C# for a mobile network provider to monitor survey customer satisfaction.
  • Created a browser plugin to integrate Avaya services with the Salesforce platform.
  • Made a web service for managing the Avaya call center recordings.
Technologies: MySQL, Microsoft Lync, Avaya Software, Salesforce, Java, C#

C++ Developer

2011 - 2012
Unify Communications
  • Developed and optimized a network discovery and device identification tool written in C#.
  • Maintained the administration and supervising tool of the call center solution written in C++.
  • Extended the administration tool with a user role management component.
Technologies: C#, C++

Interactive Information Support System

I worked on the back-end and mobile side of an interactive information support system targeted to Android platform. The control flow can make interactive decisions; for example, on keywords (voice recognition) and audience composition (size, gender, and approximate age recognition with OpenCV).

Android Application

I created a mobile application for a national grocery shop chain. It supported home delivery, as well as creating a shopping list, and adding items to the list via bar code scanning.

Internal Monitoring Site

I worked in a bigger team to maintain and introduce new features for a monitoring application. The product was only used for internal purposes—e.g., to visualize incoming data volume by type, show metrics about them, and display our coverage of the data. The technologies used were React and Backbone on the front-end and multiple back-end technologies.

Unified Metadata Search Tool

I worked in a team of four to create a metadata unifying tool which is easily extendable. The tool is capable of complex searches combining several analysis results from different sources for the same sample. The storage used was Elasticsearch because of its great full-text search capability. I mainly worked on the ETL pipeline written in Ruby; the back-end is written in Node.js and the front-end which used the AngularJS framework.

Sport ID

This is a player safety app targeted for the US market. I worked on the Rails REST back-end, mainly on geolocation queries, access control, and authorization.

I created a unified indexing and search tool which could search in multiple cloud storage areas and their metadata in near real-time.
2009 - 2013

Bachelor of Science Degree, Absolutorium in Software Information Technology

Eötvös Loránd University, Faculty of Science - Budapest, Hungary


REST APIs, Node.js, React, jQuery, OpenGL, Vue


IntelliJ IDEA, Amazon Elastic Container Service (Amazon ECS), Amazon Elastic Container Registry (ECR), MongoDB Atlas, MongoDB Shell, AWS SDK, AWS ELB, Perforce, Komodo IDE, Mercurial, Git, Vim Text Editor, Eclipse IDE, Visual Studio, Microsoft Lync


Sinatra, Ruby on Rails (RoR), Spring Boot, Spring, AngularJS, React Native, Chrome, Django


JavaScript, C++, Ruby, Java 11, Perl, Python, C, Java, CoffeeScript, C#


Microservices, REST, Service-oriented Architecture (SOA), Object-oriented Programming (OOP), Test-driven Development (TDD), Agile


Docker, Amazon EC2, Google Cloud Platform (GCP), Amazon Web Services (AWS), Linux, Salesforce, Kubernetes, Android


MongoDB, Amazon S3 (AWS S3), Spring Data MongoDB, Elasticsearch, MySQL, CouchDB


MERN Stack, Optimization, Avaya Software, Low Latency, WebSockets

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