Pavlo – React, Node.js, Typescript

Digital running-coach platform providing personalised training plans for 5K to marathon, serving 200K+ users. Owns architecture, backend API, admin panel, DevOps, and platform performance end-to-end. Full stack: TypeScript, Koa.js, PostgreSQL/Sequelize, Redis, BullMQ, AWS (S3, Pinpoint, CloudWatch), Socket.io, Stripe, Firebase, OpenAI API, Claude API, Sentry, New Relic, React, MUI, TailwindCSS, React Hook Form, TanStack Table, TanStack Query, Docker.

• Architected and owned the core backend API serving 200K+ users - Koa.js, PostgreSQL with Sequelize ORM, Redis caching, and BullMQ message queue for async job processing: scheduled training plan generation, push-notification delivery, webhook handling, and retry logic with dead-letter fallback
• Owned end-to-end DevOps: CI/CD pipelines, AWS infrastructure (S3, Pinpoint, CloudWatch), environment management, zero-downtime weekly releases, and regular dependency vulnerability analysis (npm audit, Dependabot) with remediation ownership
• Improved platform reliability and speed through PostgreSQL query optimisation, Redis caching, and connection-pool tuning - sustaining 99%+ uptime as the platform scaled to 200K+ users
• Built full-stack observability and analytics: Sentry error tracking, New Relic APM, CloudWatch alerting, and product analytics instrumentation - enabling rapid incident detection, performance regression tracking, and data-driven product decisions
• Integrated Stripe subscription billing, Firebase push notifications, and OpenAI API for AI-powered personalised coaching features - driving retention across iOS and Android with 4+ star ratings on both stores
• Built and owned the internal React admin panel (MUI, TailwindCSS, TanStack Table) - used hundreds of times daily by a 20-person coaching and operations team to manage user accounts, training plans, and subscription data
• Acted as the bridge between business and engineering - translating product goals into technical roadmaps and communicating timelines and trade-offs to non-technical stakeholders
• Led weekly planning, sprint reviews, and architecture discussions with product managers and founders, maintaining delivery momentum across the cross-functional team
• Conducted code reviews and mentored 3-4 engineers, establishing coding standards and architectural patterns that scaled the platform from zero to 200K+ users
• Accelerated day-to-day development by adopting AI-assisted coding tools - Claude Code and Cursor - for feature delivery, refactoring, and code review

Healthcare's global multi-market product catalogue platform, built within a 30-person team.

• Led the Next.js migration from Adobe AEM to Contentstack CMS
• Built search functionality under GDPR compliance using Coveo
• Improved the deployment process by creating CI/CD pipelines in Azure DevOps and configuring Next.js to work in Azure
• Improved performance and data fetching across the platform, using Next.js SSR capabilities and caching from TanStack Query

Large-scale B2B e-commerce platform for a parts distributor, built within a 30-person cross-functional team.

• Led frontend architecture for a React micro-frontend monorepo (Nx, Module Federation) serving enterprise customers across 15+ European markets
• Communicated with stakeholders to clarify and polish requirements, and provided technical knowledge to help make decisions about the product

Customer-facing transit booking and trip-planning portal, built within a 30-person team. Stack: TypeScript, Next.js, React, Contentstack CMS, Algolia, Stripe, Tailwind CSS, TanStack Query, Express, PostgreSQL, Docker.

• Built the core functionality of the booking and trip-planning portal, including design based on Figma and search across the platform using Algolia
• Implemented end-to-end integration with Stripe to introduce payments into the platform, including payments data storage and webhook handling

Official B2C hospitality and ticketing platform for the Olympic Games, built within a 30-person team. Stack: TypeScript, React, Next.js, Apollo Client, GraphQL, Contentful CMS, Datadog.

• Engineered end-to-end ticket purchasing and hospitality package booking flows, with multi-language support and live content for a global audience across 190+ countries
• Integrated Datadog into the codebase to implement full-stack observability, improving monitoring of errors and performance

Tutoring marketplace connecting tutors and students - led architecture and frontend engineering from scratch. Stack: TypeScript, React, NestJS, PostgreSQL, TypeORM, React Hook Form.

• Designed full-stack architecture (React, NestJS, PostgreSQL) and led a small engineering team
• Built a reusable React component library that accelerated feature delivery

B2B SEO/PPC analytics SaaS, built within a 4-person frontend subteam. Stack: TypeScript, React, Redux, Redux-Saga, Express, Elasticsearch.

• Delivered high-volume feature output, integrating Elasticsearch for keyword search across millions of data points
• Shipped browser extensions for Chrome, Firefox, and Opera - 30K+ combined installs

Full-stack developer at a software development agency, delivering client projects across security & IoT, workforce management, and e-commerce / agency websites. Stack: JavaScript, React, Redux, Node.js, PostgreSQL, WebRTC, HTML5/CSS3, Bootstrap.

• Built a browser-based admin panel for live IP camera monitoring via WebRTC streaming, with multi-feed grids and alert handling
• Developed a staff access platform with role-based permissions, electronic lock control, and door-access audit logging
• Delivered responsive, pixel-perfect websites and landing pages for e-commerce and agency clients