Roman Bretskii

A results-driven JavaScript Developer focused on creating solutions that meet business goals through advanced technologies. Specializes in developing custom software solutions to address unique client requirements. Strong technical background with a proven ability to deliver high-quality software within tight deadlines.

Coding is not just a job for me—it’s a lifestyle. I continuously strive to improve, knowing that in this field, growth never stops. This mindset prepares me to deliver high-quality software, even under tight deadlines.

Skills and Tools

  1. JavaScript (ES5, ES6, ES7), TypeScript, Python

  2. React, React Native, Redux (Thunk, Saga, Form), React Query, React‐Router, React Connect, Formik, Ant Design, HTML5, CSS3, LESS, SASS, Tailwind CSS, CSS‐in‐JS, DOM, Responsive Web Design

  3. Node.js, Express, MongoDB, Mongoose, REST API, WebSockets, XML, YAML, JSON, JSON Web Token (JWT), Passport.js

  4. Webpack, Git, GitHub, Xcode, Postman, Swagger, Firebase, AWS (EC2, S3), Google Cloud Platform

  5. Functional Programming, Asynchronous Programming, Server‐Side Rendering (SSR), API Development, Secure Shell (SSH), Cloud Infrastructure, Scalable Web Applications, Deployment Management

  6. Cross‐functional Collaboration, Agile, Scrum, Time Management, UI/UX Design, System Optimization, Performance Benchmarking, Trading Systems

Technical Proficiency

  1. Extensive experience in designing and implementing complex software solutions tailored to meet specific business requirements, from full‑stack web applications to high‑frequency trading systems.
  2. Strong technical background in JavaScript, with hands‑on expertise in both frontend and backend development, including React, React Native, Node.js, and Express.
  3. Proficient in building scalable, secure, and performant applications, including real‑time data processing systems and enterprise‑level business applications.
  4. Skilled in managing the full lifecycle of projects, from architecture design and development to deployment and maintenance, ensuring high‑quality outcomes.
  5. Adept at integrating and handling complex API connections, WebSockets, and database management across diverse environments, including AWS, Firebase, and Ubuntu servers.
  6. Proven ability to collaborate effectively within cross‑functional teams, ensuring that project goals align with technical execution and business objectives.

Work experience

  1. Freelance Crypto Trading Data Engineer

    Freelance, Remote

    Built high-performance WebSocket data streaming environments for multiple major cryptocurrency exchanges, including Binance, HTX, Bybit, MEXC, and BingX.

    Manually integrated exchange trading APIs by working directly through technical documentation, avoiding third-party libraries to ensure lightweight, purpose-specific implementation. Prioritized low-latency architecture by benchmarking and selecting the fastest global endpoints for optimized trading performance.

    Maintained stable and resilient data streams while ensuring clean code separation and reusable configurations across exchange-specific modules.

    Deployed and managed the system on Ubuntu-based servers, using Node.js and pure JavaScript to achieve full control and precision across all backend operations.

    Skills: Algorithms · API Development · REST APIs · Secure Shell (SSH) · Architecture Development · Amazon Web Services (AWS) · Low Latency Trading · High‐Frequency Trading · Software Development · Market Data · Redux.js · Exchange Connectivity · MERN Stack · Cryptocurrency Trading · Web Services API · Linux · Functional Programming · Server Management · Optimization · Problem Solving · Performance Benchmarking · JavaScript · Performance Tuning · MongoDB · Ubuntu · Async · Node.JS · WebSockets · Git · System Architecture · GitHub · Trading Systems · Cloud Infrastructure · Back‐end Operations

  2. Frontend JavaScript Developer

    https://din-mel.ru/

    Redesigned and modernized the company’s official website with a strong focus on clear visual structure, mobile responsiveness, and modern UI/UX principles.

    Created a fresh, minimalistic style that reflects the company’s history and core values while meeting modern market demands. Integrated marketing-friendly slogans and user-friendly information architecture, enabling easy navigation and a professional brand presence.

    Ensured high performance and visual consistency across all devices, providing a smooth and engaging user experience.

    Skills: Algorithms · API Development · REST APIs · Secure Shell (SSH) · Architecture Development · Amazon Web Services (AWS) · Low Latency Trading · High‐Frequency Trading · Software Development · Software Quality · Market Data · JavaScript Frameworks · Redux.js · MERN Stack · Scalable Web Applications · Web Services API · Linux · Express.js · Back‐End Web Development · Functional Programming · Server Management · Problem Solving · Performance Benchmarking · JavaScript · API Management · MongoDB · Ubuntu · Custom Software Development · Async · Node.JS · Application Development · Trading Software · WebSockets · Database Servers · Git · System Architecture · GitHub · Trading Systems · Cloud Infrastructure · Back‐end Operations · Deployment Management

  3. JavaScript Automated Trading System Developer

    Freelance, Remote

    Developed a high-frequency trading software designed to process and synchronize data from multiple exchanges in real-time.

    Engineered a complex backend architecture to manage and handle fast, continuous data streams through WebSockets, ensuring accurate and efficient data processing.

    Deployed and secured the system on an Ubuntu server, optimizing for performance and reliability.

    Managed the entire lifecycle of the bot, from architecture design to deployment, including the execution of real trading operations.

    Integrated and handled all necessary APIs and WebSockets, ensuring accurate price updates and position management in a live market environment.

    Skills: Algorithms · API Development · REST APIs · Secure Shell (SSH) · Architecture Development · Amazon Web Services (AWS) · Low Latency Trading · High‐Frequency Trading · Software Development · Software Quality · Market Data · JavaScript Frameworks · Redux.js · MERN Stack · Scalable Web Applications · Web Services API · Linux · Express.js · Back‐End Web Development · Functional Programming · Server Management · Problem Solving · Performance Benchmarking · JavaScript · API Management · MongoDB · Ubuntu · Custom Software Development · Async · Node.JS · Application Development · Trading Software · WebSockets · Database Servers · Git · System Architecture · GitHub · Trading Systems · Cloud Infrastructure · Back‐end Operations · Deployment Management

  4. FullStack JavaScript Developer

    Developed a comprehensive business application for a mill factory, integrating client databases, order histories, and real-time production tracking.

    Built a system to monitor and manage raw material balances, production quality, and worker shifts, with automatic updates to inventory levels and financial data.

    Implemented dashboards for real-time monitoring of balances, prices, credit/debit transactions, and payments linked to bank accounts and counteragents.

    Automated manufacturing processes, salary calculations, and financial operations, ensuring all data is securely updated and accessible 24/7.

    Managed and secured the system on MongoDB, supporting thousands of clients, orders, and transactions.

    Created integrated manufacturing journals to track analysis and repair operations.

    Skills: API Development · Ui · Architecture Development · HTML5 · Front‐End Development · Software Quality · JavaScript Frameworks · Mobile Application Design · Redux.js · Business Requirements · Cross‐functional Collaborations · Express.js · Back‐End Web Development · Functional Programming · Server Management · Google Cloud Platform (GCP) · Css3 · User Interface Design · IT Integration · HTML · Web Applications · JavaScript · React Hooks · API Management · Ubuntu · Custom Software Development · Async · Client Relations · SSL Certificates · Node.JS · Full‐Stack Development · Application Development · User Experience (UX) · Database Servers · Git · Firebase · GitHub · Cloud Infrastructure · AJAX Frameworks · Webpack · Responsive Web Design · Back‐end Operations · Business Process Integration · Deployment Management · React.js ·

  5. JavaScript React-Native Developer

    https://apps.apple.com/th/app/only-once-nextgen/id1620559285

    Developed a React Native mobile application for Only Once, a SaaS company from the Netherlands, focused on secure business data management.

    Actively contributed to both frontend development and state management using Redux.

    Integrated complex Figma designs with pixel‐perfect precision, and collaborated with an international JavaScript team to deliver a high‐quality, production‐ready app that met strict business and UX requirements.

    Skills: Software as a Service (SaaS) · React Native · Ui · REST APIs · HTML5 · Front‐End Development · Software Quality · JavaScript Frameworks · Mobile Application Design · Redux.js · MERN Stack · Cross‐functional Collaborations · Mobile Application Development · Functional Programming · Css3 · User Interface Design · Problem Solving · JavaScript · React Hooks · Custom Software Development · Async · Application Development · User Experience (UX) · Git · GitHub · Mobile Applications · Scrum · Deployment Management · React.js · Xcode

  6. Frontend JavaScript Developer

    https://din-mel.ru/

    Developed a React-based web application for the company’s online presence.

    Integrated frontend and backend services, handling client orders and transmitting data securely via a backend.

    Deployed the frontend on Firebase, managing all domain, server, and frontend operations.

    Collaborated closely with a designer to implement frontend design, ensuring a responsive and user-friendly interface.

    Skills: API Development · Ui · Architecture Development · HTML5 · Front‐End Development · Software Quality · JavaScript Frameworks · Mobile Application Design · Redux.js · Business Requirements · Cross‐functional Collaborations · Express.js · Back‐End Web Development · Functional Programming · Server Management · Google Cloud Platform (GCP) · Css3 · User Interface Design · IT Integration · HTML · Web Applications · JavaScript · React Hooks · API Management · Ubuntu · Custom Software Development · Async · Client Relations · SSL Certificates · Node.JS · Full‐Stack Development · Application Development · User Experience (UX) · Database Servers · Git · Firebase · GitHub · Cloud Infrastructure · AJAX Frameworks · Webpack · Responsive Web Design · Back‐end Operations · Business Process Integration · Deployment Management · React.js ·

  7. JavaScript Developer

    https://www.linkedin.com/in/ven-korolev/

    Developed a foundational React/Redux front web application, laying the groundwork for the company's project.

    Implemented a basic Express backend to facilitate future integrations and data flow.

    Skills: HTML5 · Front‐End Development · Software Quality · JavaScript Frameworks · Redux.js · Express.js · Functional Programming · HTML · Web Applications · JavaScript · Node.JS · Application Development · Git · GitHub · AJAX Frameworks · Webpack · Responsive Web Design · Scrum · Deployment Management · React.js

  8. Sales and Operations Planning Manager

    Coordinated sales and planning of manufacturing orders, maintaining optimal inventory levels to meet client demand.

    Handled client communications, managed order logistics, and facilitated smooth delivery coordination.

    Resolved client issues promptly and effectively, contributing to the overall customer satisfaction.

    Collaborated closely with production teams to align manufacturing schedules with sales forecasts and inventory needs.

    Skills: Sales Strategy · Product Lifecycle Management · Business Requirements · Planning & Scheduling · Problem Solving · Client Relations · Economics Education · Enterprise Management · Inventory Management · Sales Planning

Education and Qualifications

  1. Master Degree in Economics and Management of Enterprises

    Kuban State Agrarian University