Sergei is available for hire

Sergei Grigorchuk

Verified Expert in Engineering

Software Developer

Location

Tashkent, Tashkent Province, Uzbekistan

Toptal Member Since

February 23, 2016

Sergei is an experienced software developer. He has worked for IT companies from the USA, Europe, and Asia as a Java back-end and full-stack (Angular) developer. He loves his job and always looks forward to helping his clients at Toptal to create amazing projects.

Database Design Databases Java SQL MySQL PostgreSQL REST APIs Spring Boot Spring SQL Performance Microservices MySQL Performance Tuning Full-stack Ajax Spring Cloud

Portfolio

Entika

RabbitMQ, Docker, JSON/XML Schemas, Angular, Python, Business Process Modeling...

Earthlink

Swagger, REST APIs, Spring Data, Spring Security, Spring, Memcached, RabbitMQ...

Zakupay

Query Optimization, Microservices Architecture, Database Modeling, Angular...

Experience

Database Design - 20 years Java - 15 years SQL - 14 years PostgreSQL - 7 years REST APIs - 6 years Spring - 5 years Microservices Architecture - 5 years Angular - 3 years

Availability

Part-time

Preferred Environment

Docker, Apache Kafka, PostgreSQL, RabbitMQ, Angular, IntelliJ IDEA, Git, Spring Boot, Java

The most amazing...

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

Work Experience

Architect and Team Lead

2020 - 2021

Entika

Designed a business modeling framework that allows configuring the app to change/add workflow, validation, columns, permissions, actions, UI forms, and more on the fly. The admin needs to change JSON configuration files.
Acted as a project manager and team lead of a team of two Python developers and two Angular developers.
Organized a CI/CD environment on GitHub (Git flows, actions for automatic tests, and building Docker images used for automatic deployment on staging).

Technologies: RabbitMQ, Docker, JSON/XML Schemas, Angular, Python, Business Process Modeling, GitFlow, REST APIs, API Architecture, PostgreSQL

Architect, Team Lead, and Back-end Developer

2018 - 2021

Earthlink

Designed and developed high-load microservices for the back end of Iraq's 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 the response of high-load endpoints.
Integrated the back end with an existing OAuth service (IdentityServer) and an S3 service.

Technologies: Swagger, REST APIs, Spring Data, Spring Security, Spring, Memcached, RabbitMQ, High-load, Database Modeling, Spring Cloud, Spring Microservice, Redis, Apache Kafka, Elasticsearch, PostgreSQL, Spring Boot, Java

Architect, Team Lead, and Senior Java Developer

2017 - 2018

Zakupay

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, and more) files.
Designed architecture for the system (a database, load balancing, chat subsystem, and telegram integration).
Acted as the CTO of the company, organizing the following departments: R&D (four developers), QA (four testers), and DevOps (two DevOps engineers). All these departments reported to me (daily, scrum meetings, sprint planning, and more).

Technologies: Query Optimization, Microservices Architecture, Database Modeling, Angular, AngularJS, PostgreSQL, Spring Boot, Play Framework, Java

Senior Java Developer

2016 - 2017

Imandra

Designed and developed Spring Boot-based microservices for authentication, data store, analysis, and more.
Simplified the architecture of the app using npm modules instead of creating custom Imandra modules as the company did previously.
Used Docker and Kubernetes to deploy all microservices to Google Cloud environment.

Technologies: Microservices Architecture, Microservices, Docker, Angular, MySQL, Spring Boot

Architect, Team Lead, and Senior Java Developer

2011 - 2016

Cynteka

Designed and developed a business application that helps construction companies control procurement processes.
Created image definition to find the best price offer based on FineReader OCR.
Designed and created a huge database for construction materials and equipment.
Deployed the application to Microsoft Azure (load balancing, backup, server-on-demand).
Designed and created a webchat based on Web Sockets and Akka.
Acted as the CTO of the company, organizing the following departments: R&D (three developers), QA (two testers), and DevOps (one DevOps engineer). All these departments reported to me (daily, scrum meetings, sprint planning, and more).

Technologies: REST, Ajax, Bootstrap, MySQL, PostgreSQL, jQuery, Ractive.js, AngularJS, Play Framework, Java

Senior Java Developer

2008 - 2010

CMS Forex (Visual Trading Systems)

Designed and developed Forex Web Trader, an application on GWT.
Organized continuous integration processes using Jira, Bamboo, SVN, and Maven.
Designed a monitoring system for Forex trading that collected metrics and logs from servers.
Initiated a migration from Oracle to PostgreSQL. Migrated the app from Ant to Maven.
Helped design a DB check control engine that helped find problems in data.

Technologies: Hibernate, Oracle, GWT, JBoss, Apache Tomcat, Enterprise Java Beans (EJB), Java

Co-founder, Architect, and Senior Java Developer

2004 - 2007

LemoSoft

Designed and developed Lemo COBOL IDE, an IDE for COBOL developers that helps edit sources and compile and debug programs. The project was sold to Microfocus.
Created a JavaScript editor and debugger based on Eclipse for Sapience 360.
Developed a 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: JavaScript, COBOL, Java, Eclipse RCP, Eclipse

Java Developer

2003 - 2004

Enkata

Implemented data mining algorithms for a big data analysis system.
Implemented very fast text search modules based on DFA.
Developed Eclipse UI plugins, text processing algorithms.
Integrated Eclipse plugins and a web-based configuration platform.
Designed and developed a database for fast text search and processing.

Technologies: Servlet, Apache Tomcat, Eclipse, Java

Experience

Social Network (Earthlink, Iraq)

http://earthlink.iq/

I designed and developed the back end of a social network for Earthlink, the largest telecommunications company in Iraq. It's a mix of Instagram and Reddit with users, followers, groups, posts, likes, news, images, videos, and more. It's based on a microservice architecture with more than ten different microservices. All services are connected by Spring Cloud, RabbitMQ, REST API, and Zookeeper.
Years: 2018-2021

Supply Chain Management System for Construction Companies

http://zakupay.pro/

I acted as an architect, team lead, and senior Java developer for a B2B trading platform that helps construction companies to find the best offers. It collects orders from constructors, organizes tenders, and controls payments and deliveries. More than 10K people use this system every day for their job.
Years: 2012-2018

Business Process Modeling (Entika)

I was the main architect and team lead of the business process modeling platform. The platform contains descriptors for workflows, entities, validation rules, permissions, UI form, UI registries, and more. The main goal is to create business applications easily and rapidly.
Years: 2020

Microfocus Visual COBOL for Eclipse

https://www.microfocus.com/en-us/products/visual-cobol-personal-edition/overview

In 2004, I founded 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 six months, passing on my experience.
Years: 2004 - 2007

Cynteka Pivot Table

http://ukman.github.io/

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

WebTrader for Forex CMS Trading Platform

I developed WebTrader, an online client for Forex traders. In addition to the classic VT Trader, WebTrader allowed traders to perform operations without installing a Windows desktop application.
I used JavaScript, Ext.js, jQuery, Ajax, Long Polling, and GWT. It worked very fast and was stable.
Years: 2008-2010

Skills

Languages

SQL, Java, HTML, JavaScript, COBOL, Python, GraphQL, HTML5, Scala, CSS3, Python 3

Frameworks

Spring, Spring Boot, Play, Swagger, Play Framework, OAuth 2, Spring Microservice, AngularJS, Bootstrap 3, Spring JDBC, Hibernate, Angular, Bootstrap, GWT, Ext JS, Spring Security, JPA, Selenium, Mockito, Akka, Django

Libraries/APIs

REST APIs, jQuery, Ebean ORM, OpenID, Django ORM, Vue 2, Ractive.js, React, Auth0 API, Node.js, jQuery UI, Google Speech API, Keras, TensorFlow, OpenCV

Tools

MySQL Performance Tuning, Git, GitHub, Servlet, Apache Maven, IntelliJ IDEA, RabbitMQ, Elastic, Gradle, Docker Compose, Bower, Eclipse IDE, Eclipse RCP, Apache Tomcat, Apache ZooKeeper, Eureka

Paradigms

Database Design, Microservices, Microservices Architecture, REST, API Architecture, Compiler Design, STOMP, High-speed Design

Storage

Databases, Database Modeling, PostgreSQL, MySQL, SQL Performance, Database Performance, Spring Data, Redis, JSON/XML Schemas, Amazon S3 (AWS S3), Spring Data REST, ClickHouse, Memcached, Elasticsearch

Other

Code Architecture, Query Optimization, Parsers, RESTful Microservices, GitFlow, Business Process Modeling, Telegram Bots, TextSearch, Mathematics, Full-stack, Ajax, HTTP, High-load, Spring Cloud, Big Data, Business, Long Polling, Abstract Syntax Trees (AST), Source Code Lexing, Classification Algorithms, Learning, Object Detection, Facial Recognition, Machine Vision, Computer Vision, Boot, Text Processing, SVG, OCR, Apache Commons, WebSockets, Neural Networks, Enterprise Java Beans (EJB), Programming, Algorithms, OOP Designs

Platforms

Docker, Linux, JBoss, Oracle, Eclipse, Telegram Bot Platform, Kubernetes, Azure, Amazon Web Services (AWS), Apache Kafka

Education

1996 - 2002

Master of Science Degree in Applied Math

State Electrotechnical University (LETI) - Saint Petersburg, Russia

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