Petko Stoyanov

Built and maintained production-grade data-intensive web applications using React, TypeScript, Node.js, Express, MongoDB, and real-time communication. Owned full-stack features including MongoDB schema design, backend APIs, automated testing, deployments, and production monitoring. Developed responsive UIs with reusable functional components, hooks, and modular frontend architecture, and delivered data-heavy dashboards with charts, tables, filtering, pagination, and interactive visualizations. Implemented resilient WebSocket/Socket.IO clients with robust connection lifecycle management and optimized rendering for frequently changing dashboard data. Designed and built backend services exposing REST APIs with authentication/authorization middleware, standardized validation and error handling, and efficient data access patterns. Optimized MongoDB collections with compound/selective indexes, improved query performance using explain plans and execution stats, and implemented aggregation pip

Developed production web platforms using React, TypeScript, Node.js, Express, MongoDB, REST APIs, and real-time communication patterns. Owned full-stack features spanning database models, backend business logic, REST APIs, frontend state, user interfaces, testing, and production support. Built responsive React interfaces for dashboards, workflow applications, reporting, and enterprise tools. Used Redux/Redux Toolkit for complex shared state and async application flows. Implemented Node.js/Express REST APIs with validation, authentication/authorization, structured errors, pagination, and filtering. Designed MongoDB schemas for high-volume and event-driven data, built aggregation pipelines for reporting and analytics, and optimized slow queries by reducing scanned documents and improving access patterns. Implemented WebSocket-based updates and handled connection lifecycle, subscriptions, and event-driven UI updates, along with transaction-oriented backend workflows and integration with t

Built full-stack web applications using JavaScript, TypeScript, React, Node.js, Express, MongoDB, and REST APIs. Developed responsive React interfaces from reusable components and integrated them with backend services. Implemented Redux-based state management for data-intensive front-end workflows and shared application state. Created dashboards and reporting UIs with charts and table features (filtering, sorting, pagination). Developed backend APIs with modular routing, middleware, validation, authentication, and error handling. Designed MongoDB collections and document models for transactional and operational application data, adding indexes to improve filtering, sorting, and lookup performance. Implemented event-driven real-time functionality using WebSockets, improving performance through caching and query/pagination optimizations. Added automated tests for front-end and backend functionality and supported CI/CD workflows using Git, Docker, Linux, and standard tooling.