Front-end JS Expert for Defi Exchange2021 - 2022Cryptobuilders OÜ
- Developed a decentralized exchange website for a new layer 1 blockchain.
- Implemented a Next.js-based UI for Automated Market Maker (like Uniswap).
- Configured Fleek.co deployments for development and production environments.
Full-stack Node.js and React Developer2021 - 2021Finzio
Technologies: Node.js, React, PostgreSQL, Docker, Git, SQL, Database Design, Full-stack, Job Schedulers, HTML Email, CRM APIs, Web Portals, Wikis, Wizards, Forms, JSON, API Integration, Web Dashboards, SQL Stored Procedures, PL/pgSQL, Matching Systems, Business Process Analysis, MJML, Custom CMS Development, Stripe, Database Triggers, Ubuntu Server, Web Development
- Developed a system that matches users with financial advisors based on their location and answers in a multi-step wizard. This includes a sophisticated ranking algorithm with a live preview of the map results.
- Developed a ranking algorithm that takes multiple parameters into account and their importance in the context of each particular search run. Its capabilities exceed any currently popular financial advisory matching websites.
- Developed a WYSIWYG email template editor based on MJML embedded into the admin console.
- Developed a JSON-based format for describing multi-step wizards and a React engine to run those wizards. This includes text variation via shortcodes, logging, reports, integration with analytics and social networks, and emails.
Full-stack PHP and React Developer2019 - 2021Toptal, LLC
Technologies: PHP 7, APIs, Babel, Webpack, Docker, Online Forms, Web Worker, Twitter, Bootstrap, SaaS, JSON API, Mutex, REST APIs, PostgreSQL, React, PHP, Next.js, Vercel, Database Triggers, Ubuntu Server, Web Development, PL/pgSQL, Xdebug
- Designed and developed a web application for speed coding competitions that Toptal uses to attract new talent at conferences, meetups, and online.
- Optimized mutexes to prevent database transaction race conditions in a non-blocking way and Nginx micro-caching for high-load.
- Created the PostgreSQL database schema and developed a custom PHP framework.
- Developed the Docker containers for both development and production environments.
- Integrated with Matomo, an open-source PHP analytics software.
React Front-end Engineer, Core Team2019 - 2019Toptal, LLC
Technologies: Docker, NGINX, APIs, Babel, Git, Jest, Webpack, MUI (Material UI), CSS, Styled-components, React Router, React Final Form, Apollo, GraphQL, React, TypeScript, Custom CMS Development, Web Development, Code Review
- Developed Toptal Picasso React components, a shared UI library that leverages the power of React Hooks.
- Architected new staff portal pages using TypeScript and React with Hooks.
- Mentored, reviewed code, and helped architect Toptal's staff portal as a tech lead's team member.
- Helped shape GraphQL schema for the back-end team.
- Developed business flow diagrams based on multiple specifications and sources of knowledge about the Toptal systems.
- Built multi-step wizards and complex forms with combined client-side and server-side data validation and error handling.
React/Redux Developer2019 - 2019Realtime Media
Technologies: MongoDB, C#, SVG, Fabric, Canvas, Redux, React, Custom CMS Development, Web Development, React Redux
- Developed in-browser games using the Canvas API, Fabric, SVG, and React.
- Contributed to the development of a rewards platform web application.
- Developed a React-based, JSON-schema-driven theme editor for games.
- Refactored old React code to use the newer React Hooks feature.
- Developed a browser extension for Firefox that aids the team in testing complex scenarios of the loyalty/rewards engine.
Lead PHP/React Web Developer2018 - 2019XZERES
Technologies: Integration Testing, NGINX, PHP 7, APIs, Git, Bootstrap, HTTP API, React, PostgreSQL, PHP, Webpack, Docker, Next.js, Custom CMS Development, Twig, Database Triggers, Ubuntu Server, Web Development, PL/pgSQL, Xdebug
- Developed a wind turbine management website automating business processes and interaction between turbine owners, landlords, technicians, helpdesk team, and XZERES staff. Developed a proprietary framework for this project.
- Built dashboards displaying gauges with live turbine data and statistics, e.g., current wind direction, the total energy produced, and outages, among other things.
- Created an API to make it possible for other teams to integrate third-party tools and applications with the XZERES system.
- Implemented user and turbine registration forms and a corresponding back end for administrators to review applications.
- Developed, installed, and maintained Docker containers for development and production environments.
- Internationalized and localized the XZERES web application using i18next and gettext. Installed and integrated Weblate to ease translator collaboration.
- Integrated ReactPHP, a low-level library for event-driven programming in PHP, to schedule and run background tasks that fetch and store data from hundreds of wind turbines in Japan and other countries.
Senior Web Developer2014 - 2018Veer West, LLC (as FormAssembly)
Technologies: Integration Testing, NGINX, PHP 7, APIs, Gherkin, Behat, PHPUnit, Microservices, Docker, Functional Programming, Object-oriented Programming (OOP), Regular Expressions, jQuery, React, MySQL, PHP, Stripe API, Custom CMS Development, Stripe, Twig, Database Triggers, Ubuntu Server, Web Development, TinyMCE, Code Review, Xdebug
- Integrated FormAssembly with Stripe, Chargent, iATS, and eWay payment gateway APIs.
- Built graphs and charts to visualize statistics for 100+ thousand form submissions (used Plotly charts library).
- Developed a plugin for TinyMCE WYSIWYG editor that highlights and validates the syntax of Excel formulas.
- Coded an internal client scoring system based on the client activity, billing records, content in their forms, and other factors.
- Developed a React-based framework that unified user experience in connectors to payment gateways, Salesforce, Mailchimp, and other third-party APIs.
- Sped up archiving and exporting thousands of files attached to form responses, from 10+ minutes down to a few seconds.
- Upgraded Salesforce integration to use the latest API features.
- Developed unit tests using PHPUnit and Behat/Gherkin. Wrote scenarios for QA engineers.
- Helped the DevOps team to move the developer environment from Vagrant to Docker.
Lead PHP Web Developer2012 - 2013NotarZvit
- Designed an online service for Ukrainian notaries for bookkeeping and running the notary acts registry.
- Developed a PDF generation module for notaries to build reports and submit the reports to the Department of Justice in Ukraine.
- Integrated with Mailchimp mailing list and implemented email campaign business logic.
- Configured a web server for the client by installing a LAMP stack on Ubuntu; deployed and regularly updated the application.
PHP Web Developer2007 - 2012ProfitProtector Limited (UK)
- Developed analytics and monitoring tools for ClickBank affiliates, including database schema design, CodeIgniter PHP framework, integrating with ClickBank API and Alexa API, web scraping, and building graphs and charts.
- Coded a sport betting automation tool (C#, Betfair API).
- Developed an online company registration service, which included integrating with the government company registration API, generating PDFs, developing online forms, and developing the public website of the service.
Software Developer2005 - 2006Kyiv National University of Construction and Architecture
Technologies: Software, Windows, PDF, XML, Visual Component Library (VCL), Delphi, Xdebug
- Developed student exam software for the university. Used Delphi and VCL components, and XML to save tests. It was used by one faculty member to automate the theoretical part of exams, i.e., quizzes.
- Generated PDF reports for both students and examiners.
- Deployed the exam software to multiple classrooms.