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Vitalii O
Position: Senior Full-Stack Developer
Address: Khmelnytskyi, Ukraine

SUMMARY
I have a flair for creating elegant solutions in a reasonable amount of time. In my career, I have had chances to work
and improve heavy-loaded systems with excellent response times and Google page ranking.

COMPUTER SKILLS
Programming Languages
• Preferred: Python, Ruby, ES6, Node.js
• Familiar with: PHP, Go, Elixir, Typescript

Platforms
• Linux Ubuntu, Debian, CentOS
• AWS services, Google Cloud, Heroku

Software
• IDE: VS Code
• Database: PostgreSQL, MySQL, Redis, MongoDB
• Servers: Nginx, Apache, Passenger, Puma
• Tools: Git, Asana, Jira, Jenkins, Circle CI

Technologies, frameworks
• HTML, CSS, HAML, SASS
• JavaScript, ES6, jQuery, Coffescript, Node, React, Redux, Vue, Nuxt, SSR
• Python/Django/Flask, Ruby/Ruby On Rails
• Elixir, Phoenix, Go

EXPERIENCE
NDA 2019 – present
• Contributed to a CRM platform for a logistics company, streamlining shipment and delivery management
• Collaborated with a cross-functional team to develop and maintain core features
• Optimized database queries and background job processing for better performance
• Worked on internal tools and automation to improve logistics operations
• Ensured system reliability and scalability to handle high-volume transactions
• Ruby on Rails, PostgreSQL, Redis, Sidekiq, and Kafka

• Built a public sale platform for blockchain currency, enabling secure and efficient transactions
• Handled edge cases in the sale process to ensure transaction integrity
• Implemented background processing for blockchain transactions using Sidekiq
• Ensured data authenticity at both the database and blockchain levels
• Optimized system performance for handling high-volume transactions
• Ruby on Rails, MySQL, Redis, Sidekiq, and REST API

• Blockchain portal for a crypto network to showcase network features and facilitate seamless interaction with the
blockchain
• Implemented background processing for handling blockchain transactions efficiently
• Designed and developed an API layer to interact with the blockchain network
• Optimized database performance for storing and retrieving blockchain-related data
• Ensured smooth deployment and infrastructure management using Terraform
• Ruby on Rails, MySQL, Terraform, and REST API

• Platform for language teachers to conduct video lessons, featuring AI-powered notes and post-lesson AI processing
• Designed and implemented the API to support lesson management and AI-powered features
• Integrated ChatGPT and defined rules for AI-driven background processing
• Managed file uploads for lesson materials and student interactions
• Developed a scheduling system for lesson management and teacher availability
• Ruby on Rails, PostgreSQL, Redis, REST API, Sidekiq, ChatGPT integration, and Terraform
 • crossword-solver.io - developed a robust word finder tool that assists users in finding the highest-scoring words for
games such as Scrabble, Anagrams, Jumble, and various other word-related challenges. This tool features an effective
word generator algorithm. It is built on the Django framework, utilizes Elasticsearch for search capabilities, and employs
Vue for its user interface.
A website that primarily assists with solving American crosswords, including those from The New York Times, Los
Angeles Times, and others, as well as various crossword puzzles.
• Setting up and maintaining an Elasticsearch system containing several million documents, with hourly data
imports
• Configuring Cloudflare and Redis caching to ensure rapid responses for dozens of requests per second
• Optimizing Queries in PostgreSQL Database
• Managing various asynchronous tasks such as the import/export of data and analytics, which occur on an hourly,
daily, or event-triggered basis

• word.tips website and API for it's WordFinder mobile application, which helps with solving different anagram games
• Setting up Cloudflare caching
• Managing an API using Go and Python, which includes optimizing search algorithms and integrating new
endpoints
• Adding new features to Nuxt and migrating server-side rendering (SSR) code to Cloudflare
• Developing a Chrome extension for web scraping for internal use

• matholia.com is an online primary mathematics platform that aligns with the latest curriculum from the Singapore
Ministry of Education. This comprehensive learning portal offers a variety of interactive content designed to help
students excel in all aspects of primary mathematics, while also giving teachers and parents the tools to closely track
students' progress throughout the curriculum.
• Upgrade Rails to the latest version
• Update the API to support new JavaScript lessons and remove obsolete Flash-based lessons
• Enhancing user profiles with additional features and statistics, and updating the workflow for assignments

• Designed and developed a custom, multifunctional unified CMS to manage various news and quiz websites,
incorporating A/B testing in line with best practices in software design
• Implemented adaptable solutions for image upload, content caching, and CSV data importation
• Addressing performance and reliability concerns
• A proxy server featuring a web interface and scraping capabilities utilizing Node.js (with Express.js middleware)
• Retrieving data from a server utilizing a Trie data structure
• Built with: Django, Vue.js, Stimulus, and Elasticsearch

MassMedia Group 2017 – 2019
• Built an intuitive and powerful network activity monitoring tool. Found solutions for front-end performance issues around
load times, used data binding and implemented back-end API interaction. Improved the back-end application scalability
and stability. Technology stack: React, Redux, Thunk, Axios, Web Sockets, Ruby on Rails, Sidekiq
• Designed and implemented a multi-faceted restaurant menu management system according to software engineering
the best principles. The project was an SPA built with Vue, Web Sockets, Ruby on Rails and Sidekiq.
• Developed a data visualization dashboard application for Elasticsearch with Ruby on Rails and React.
• Mostly worked with: Ruby on Rails, React, Redux, Thunk, Axios, Web Sockets, Sidekiq, Vue and Elasticsearch

PHP Freelance Developer 2016 – 2017
• Developed various online stores running on Magento. Integrated payment and delivery services.
• Created custom plugins for popular PHP based CMSs.
• Mostly worked with: Magento, PHP, Ruby on Rails

EDUCATION
Master's degree in Computer Engineering at Khmelnytskyi National University 2014 - 2019

PERSONAL INFORMATION
• Age: 28
• Spoken languages: Ukrainian (native), English (conversational)
• Adaptable, responsible and reliable