Sergei Grigorchuk, Full-stack Developer in Saint Petersburg, Russia
Sergei Grigorchuk

Full-stack Developer in Saint Petersburg, Russia

Member since January 25, 2016
Sergey is an experienced software developer. He has worked for IT companies from the US and the UK as a full-stack developer. He loves his job and always looks forward to helping his clients at Toptal to create amazing things.
Sergei is now available for hire




Saint Petersburg, Russia



Preferred Environment

Java, Spring Boot, Git, IDEA, Eclipse IDE, Angular

The most amazing...

...thing I've coded is a business application that is used by thousands of people every day in their job.


  • Architect, Team Lead

    2018 - 2020
    EarthlinkTele (via Toptal)
    • Designed and developed a high-load microservice back end for a social network.
    • Integrated more than 10 different microservices with Spring Cloud.
    • Improved the performance of PostgreSQL by caching data in Elasticsearch.
    • Integrated the back end with Redis for caching response of high-load endpoints.
    • Integrated the back end with an existing OAuth service (IdentityServer) and S3 service.
    Technologies: Java, Spring Boot, PostgreSQL, ElasticSearch, Kafka, Redis
  • Senior Java Developer, Architect

    2017 - 2018
    • Designed a service based on big data and machine learning for identifying categories of construction materials.
    • Designed and developed a neural analysis service of documents that extracts data from typical (DOCx, XLSx, PDF, PNG...) files.
    • Designed architecture for the system (DB, load balancing, chat subsystem, Telegram integration).
    Technologies: Java, Play Framework, Spring Boot, PostgreSQL, AngularJS
  • Senior Java Developer

    2016 - 2017
    Imandra (via Toptal)
    • Designed ad developed Spring Boot-based microservices for authentication, data store, analysis, etc.
    • Simplified the architecture of the app using npm modules instead of creating custom Imandra Modules like the company did previously.
    • Used Docker-Kubernetes to deploy the app.
    Technologies: Spring Boot, MySQL, Angular, Docker
  • Senior Java Developer

    2011 - 2015
    • Designed and developed a business application that helps construction companies control procurement processes.
    • Created web chat based on WebSockets.
    • Created image definition to find the best price offer. It's based on FineReader OCR.
    • Designed and created a huge DB for construction materials and equipment.
    • Deployed the application to MS Azure Cloud (load balancing, backup, server-on-demand).
    Technologies: Java, Play Framework, AngularJS, Ractive.js, jQuery, PostgreSQL, MySQL, Twitter Bootstrap, Ajax, REST
  • Senior Java Developer

    2008 - 2010
    CMS Forex (Visual Trading Systems)
    • Designed and developed Forex Web Trader, an application on GWT.
    • Organized continuous integration processes (Jira + Bamboo + SVN + Maven).
    • Designed a monitoring system for Forex trading that collected metrics and logs from servers.
    • Initiated a migration from Oracle to PostgreSQL.
    • Helped design a DB check control engine that helped to find problems in data.
    Technologies: Java, EJB, Tomcat, JBoss, GWT, Oracle, Hibernate
  • Co-founder, Architect, Senior Java Developer

    2004 - 2007
    • Designed and developed Lemo COBOL IDE, an IDE for COBOL developers that helps to edit sources, compile, and debug programs. The project was sold to Microfocus.
    • Created a JS editor and debugger (based on Eclipse) for Sapience 360.
    • Developed server-side functionality in Java for Ingenico that produces a payment terminal for VISA, MasterCard, etc.
    • Developed a model-driven-architecture engine for accounting software.
    • Designed and developed a web-based math document system for students (Online Mathcad light).
    Technologies: Eclipse, Eclipse RCP, Java, COBOL, JavaScript
  • Java Developer

    2003 - 2004
    • Implemented a data mining algorithms for a big data analysis system.
    • Implemented very fast text search modules based on DFA.
    • Developed Eclipse UI plugins.
    • Integrated Eclipse plugins and a web-based configuration platform.
    • Designed a DB for fast text search.
    Technologies: Java, Eclipse, Tomcat, Servlets


  • Microfocus Visual COBOL for Eclipse (Development)

    In 2004, I founded the startup Lemosoft, which developed Lemo COBOL IDE. In 2007, Microfocus bought Lemo COBOL IDE and founded Microfocus Visual COBOL for Eclipse. I worked for Microfocus as an expert in London for 6 months, passing on my experience.

  • Procurement Chain Software for Construction Companies (Development)

    A trading platform that helps construction companies to find best offers. It collects orders from constructors, organizes tenders, and controls payments and deliveries.

  • Cynteka Pivot Table (Development)

    Cynteka Pivot Table is a jQuery plugin for websites. It supports all the usual pivot table features: data rotating, dragging and dropping fields, summarization, etc.

  • WebTrader for Forex CMS Trading Platform (Development)

    I developed WebTrader- online client for Forex traders. In addition to classic VT-Trader WebTrader allowed traders to perform operations without the need to install a Windows application.

    I used JS, Ext.js, jQuery, Ajax, Long Polling, and GWT. It worked very fast and stable.

  • Entertainment Fun Videos (Development)

    This my own small project. I created this web application that collects small fun videos from YouTube and allows users to merge some videos into a single video. It is used by people to congratulate friends, to create fun videos with politicians, and so on.

    Here's a "Happy birthday" example video for a Russian girl, Julia.

    I used Java, Play, MySQL, Ractive, Bootstrap, and Linux video utilities.


  • Languages

    SQL, Java, HTML, JavaScript, GraphQL, HTML5, Scala, CSS3, Python 3
  • Frameworks

    Play, AngularJS, Hibernate ORM, Bootstrap 3, Spring JDBC, Hibernate, Spring Security, Spring Boot, JPA, Selenium, Mockito, Akka, Django, Angular
  • Storage

    MySQL, PostgreSQL, Spring Data REST, Spring Data, ClickHouse, Memcached, Elasticsearch
  • Libraries/APIs

    jQuery, Ebean ORM, Vue.js 2, Ractive.js, React, Auth0 API, Node.js, jQuery UI, Stomp.js, Google Speech API, Keras, TensorFlow, OpenCV
  • Tools

    Servlet, Maven, Gradle, Docker Compose, Bower, Eclipse IDE, Eclipse RCP, Apache Tomcat, Apache ZooKeeper, Eureka
  • Paradigms

    REST, Microservices, STOMP, High-speed Design
  • Platforms

    Linux, Telegram Bot Platform, Kubernetes, Docker, Azure, Amazon Web Services (AWS), Apache Kafka
  • Other

    Telegram Bots, TextSearch, Math, Full-stack, Ajax, HTTP, Classification Algorithms, Learning, Object Detection, Facial Recognition, Machine Vision, Computer Vision, Boot, Text Processing, SVG, OCR, Apache Commons, WebSockets, High-load, High Availability, Spring Cloud, Neural Networks


  • Master of Science degree in Applied Math
    1996 - 2002
    State Electrotechnical University (LETI) - Saint-Petersburg

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