Designed and implemented full subscription billing flow using Stripe for SaaS platform (electronic residency & online courses).

Built dynamic pricing plan selection UI (plan cards, state handling, validation).

Configured and managed Stripe products, prices, and subscription models.

Implemented secure webhook processing (subscription lifecycle events, payment success/failure, renewals, cancellations).

Handled checkout sessions, payment validation, and backend synchronization with database.

Implemented subscription expiration logic and access control based on billing status.

Built error handling flows for failed payments, declined cards, expired sessions, and retry logic.

Integrated billing state with existing GraphQL backend architecture.

Tech Stack: Vue, GraphQL, Express, MariaDB, Stripe.

Architected and developed interactive SPA-like application with complex state management and animated UI flows.

Implemented dynamic card-based workflow with full CRUD operations (create, edit, delete, reorder).

Built advanced carousel/swipe interaction system with vertical and horizontal navigation logic.

Implemented accessibility-first interaction model (keyboard navigation, focus management, state control).

Designed and integrated backend communication layer with Laravel API. Implemented data synchronization logic between client state and PostgreSQL database.

Debugged and validated API contracts via Swagger.

Developed a simplified version of the application for Telegram Mini Apps.

Integrated Telegram WebApp API for authentication, context data, and client–server interaction.

Tech Stack: Nuxt 3, Vue 3, Laravel, PostgreSQL, Telegram WebApp API.

Architected and developed interactive SPA-like application with complex state management and animated UI flows.

Implemented dynamic card-based workflow with full CRUD operations (create, edit, delete, reorder).

Built advanced carousel/swipe interaction system with vertical and horizontal navigation logic.

Implemented accessibility-first interaction model (keyboard navigation, focus management, state control).

Designed and integrated backend communication layer with Laravel API.

Implemented data synchronization logic between client state and PostgreSQL database.

Debugged and validated API contracts via Swagger. Developed a simplified version of the application for Telegram Mini Apps.

Integrated Telegram WebApp API for authentication, context data, and client–server interaction.

Tech Stack: Vue 3, Node.js (Koa, later NestJS), PostgreSQL

Worked on legacy Angular application with RxJS-based state management architecture.

Developed and extended modular banner editor system with complex UI logic.

Implemented new editor features (photo albums, animation flows, dynamic layouts).

Fixed critical bugs in legacy editor modules and refactored unstable components.

Implemented drag-and-drop functionality and Canvas-based rendering logic.

Built adaptive, responsive editor interface with cross-device support.

Implemented editor history tracking using PostgreSQL to support rollback/versioning logic.

Generated optimized vanilla JavaScript output for embedding banners across external websites.

Worked extensively with iframe-based rendering and isolation strategies.

Performed performance optimizations across rendering and state update flows.
Tech Stack: Angular 14, RxJS, Node.js, PostgreSQL, Canvas API, iframe integration.

Integrated Web3 functionality using Ethers.js and MetaMask.

Implemented wallet connection, message signing, and transaction handling flows.

Interacted directly with smart contracts (read/write methods).

Implemented staking logic (deposit, withdraw, reward tracking).Built UI flows for staking lifecycle and transaction state management.

Implemented gas estimation and transaction status tracking (pending / confirmed / failed).

Supported multi-network environments (testnet / mainnet configurations).

Designed frontend logic assuming blockchain as backend (on-chain state synchronization).

Tech Stack: Vue 2 / Vue 3, Ethers.js, Web3, MetaMask, Smart Contracts.

Contributed to development of internal banking administration system.

Developed salary management module for enterprise clients (payroll calculation and processingworkflows).Implemented UI components and business logic for financial data handling.

Collaborated closely with multiple internal departments to integrate new features into complex bankinginfrastructure.Worked within microservices-based architecture and coordinated API integrations across teams.

Ensured compliance with enterprise-level quality and security standards.
Tech Stack: React, Angular, enterprise microservices environment.

Worked within large Scrum-driven enterprise environment with structured backlog and requirementworkflows.

Collaborated closely with product owners, Scrum coaches, and cross-functional teams.Participated in architectural discussions for new version of claim-check system.

Contributed to redesign and implementation of updated claim-check module.

Improved internal CMS/CMA systems and supported website accessibility enhancements.

Worked within Rancher-based infrastructure and distributed environment.

Tech Stack: React, Ember.js, PHP, WordPress, Play Framework, Rancher.

Delivered high-volume marketing landing pages with rapid turnaround (3–4 releases per day).

Implemented complex animation systems optimized for low-end mobile devices and unstable networkconditions.

Focused on performance optimization (event loop behavior, timers, DOM manipulation efficiency).

Developed custom hybrid mobile applications using Cordova, including internal engine to convert webplatforms into mobile apps.

Built mobile application aggregating multiple gaming platforms into unified interface.

Contributed to separate startup project using Cordova + Framework7 + GSAP.Integrated third-party services (Facebook API, external event platforms such as Concert.ua).

Participated in architectural decisions and collaborated closely with art director on UX and technicalfeasibility.

Developed and maintained advanced cross-client email systems and custom internal email renderingengine.

Tech Stack: JavaScript, Cordova, Framework7, Pixi.js, GSAP, Quasar, MJML, responsive emailsystems.