Ihor Romanchuk, Developer in Kraków, Poland
Ihor is available for hire
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Ihor Romanchuk

Bio

Ihor is a results-driven technical lead with over a decade of experience in full-stack development, scalable architecture, and team leadership. He drives engineering excellence through hands-on coding, system design, and mentoring. He's delivered high-performance front-end features and AI-powered back-end systems across diverse projects. Ivor's passionate about solving complex problems with modern tech and building teams that deliver lasting impact.

Portfolio

Connor Florczyk
React, Node.js, HTML, CSS, APIs, Large Language Models (LLMs), Tailwind CSS...
PCI Energy Solutions
React, TypeScript, Data Visualization, Unit Testing, Playwright...
PharmaRockIT
Artificial Intelligence (AI), Technical Leadership, React, C#, TypeScript...

Experience

  • JavaScript - 11 years
  • C# - 11 years
  • SQL - 11 years
  • CSS - 11 years
  • React - 7 years
  • TypeScript - 7 years
  • ASP.NET Core - 6 years
  • Amazon Web Services (AWS) - 5 years

Preferred Environment

Docker, Amazon Web Services (AWS), React, TypeScript, Node.js, C#, SQL, Cursor AI, Terraform Cloud

The most amazing...

...accomplishment was architecting and leading PharmaRockIT, a scalable, secure, multi-tenant solution hosted on AWS with a team I built from scratch.

Work Experience

Senior Full-stack Developer

2026 - PRESENT
Connor Florczyk
  • Transformed a client-supplied AI-generated prototype into a production-ready wealth-management CRM, fixing a broken LLM pipeline, multi-file uploads, and mock-data leaks to ship a working advisor demo.
  • Built an end-to-end LLM brief-generation pipeline (NestJS + OpenRouter + Langfuse) that turns PDF statements, notes, and emails into an 8-section structured brief validated with a Zod schema.
  • Provisioned full AWS infrastructure as code with eight Terraform modules (VPC, RDS, ECS Fargate, ALB, S3, CloudFront, Cognito, CloudWatch) across two environments, deployed via GitHub Actions.
  • Integrated Nylas (OAuth email/calendar sync), OpenRouter (LLM inference), and Langfuse (versioned prompts + tracing) behind clean NestJS services with graceful config-driven fallbacks.
  • Delivered a React 19 + Vite + Tailwind 4 + Shadcn client with OIDC auth and an RTK Query data layer auto-generated from the OpenAPI spec, keeping back-end types and UI in lockstep across around 19,000 lines of code.
  • Designed a multi-tenant NestJS 11 + Prisma 7 + PostgreSQL 18 API across 8 domain modules, enforcing Cognito-scoped tenant isolation on every query.
Technologies: React, Node.js, HTML, CSS, APIs, Large Language Models (LLMs), Tailwind CSS, Fintech, Amazon Web Services (AWS), AWS ECS Fargate, TypeScript, Vite, OpenAI API, Langfuse, Azure, Google Cloud, Nylas API, Amazon Cognito, Shadcn, Shadcn UI, NestJS, PostgreSQL, Terraform, Terraform Cloud, GitHub, GitHub Actions, CI/CD Pipelines, Docker, Load Balancers, Amazon CloudFront CDN, Logging, Cursor AI, Claude Code, AI Engineering, Solution Architecture, Web UI Design, Code Auditing, HTTP, Middleware, Scalable Web Services, Scalability, Software Design, Vibe Coding, Model Context Protocol (MCP), OAuth 2, Generative Artificial Intelligence (GenAI), Cloud Architecture, Multitenancy, LLM Integration, Startup Consulting, Technical Project Management, UX Design, Amazon Elastic Container Service (ECS), Multi-tenant Architecture, Zod, OXC (Oxlint), Tailwind UI, Deployment, Relational Databases, Finance, Data Engineering, Optical Character Recognition (OCR), Refactoring, Document Processing, Model Evaluation, Multi-tenant SaaS, Technical Architecture, Claude API

Senior UI Developer

2025 - 2026
PCI Energy Solutions
  • Led a full architectural refactor of a React-based data-visualization application, restructuring the codebase around feature- and page-oriented modules to improve maintainability, scalability, and onboarding efficiency for future contributors.
  • Improved page load times by approximately 10x by implementing RTK Query-based client-side caching, concurrent API requests, minimizing payload sizes through selective data querying, and configuring optimal HTTP cache-control headers on the hosting.
  • Migrated the front-end build system from Create React App to Vite, reducing development build times and improving production bundle performance while modernizing the tooling stack.
  • Introduced strict end-to-end TypeScript coverage across the application, eliminating untyped code paths, improving compile-time safety, and significantly reducing runtime errors during feature development.
  • Designed and implemented a fully client-owned visualization layer, replacing Apache Superset-dependent rendering with extensible, reusable chart and table components, enabling faster iteration and easier support for new visualization types.
  • Built a customizable dashboard system with flexible grid layouts, allowing users to compose dashboards dynamically by arranging visualizations within a multi-tab, hierarchical layout structure without reliance on external BI tooling.
  • Developed data migration scripts to decouple the application from Apache Superset, transferring historical configuration and metadata from Superset’s PostgreSQL database into the application’s own schema using Node.js and Prisma ORM.
  • Enabled long-term product independence from third-party BI tooling, reducing operational complexity and licensing risk by fully internalizing visualization, layout, and data-management responsibilities.
Technologies: React, TypeScript, Data Visualization, Unit Testing, Playwright, Progressive Web Applications (PWAs), Chart.js, Redux, Front-end Architecture, Webpack, Vite, Jest, React Query, Redux Toolkit, Node.js, Prisma, AG Charts, Performance, Web Performance Optimization (WPO), Superset, Apache Superset, PostgreSQL, OpenAI, React Grid Layout, UI Testing, Dashboards, Zustand, Application State Management, Claude, ChatGPT, Claude Code, Anthropic, Artificial Intelligence (AI), Solution Architecture, Web UI Design, HTTP, Middleware, Software Design, Model Context Protocol (MCP), LLM Integration, UX Design, Zod, TanStack Router, Relational Databases, React Testing Library, Refactoring, Multi-tenant SaaS, Technical Architecture, Claude API

Tech Lead

2024 - 2025
PharmaRockIT
  • Led a team of five developers, overseeing critical technical decisions and mentorship, ensuring the timely delivery of PharmaRockIT applications.
  • Designed and implemented a secure, scalable, and performant architecture for a multi-tenant pharmaceutical software solution, supporting admin panel, LIMS, and future electronic work book modules.
  • Managed the hiring process successfully, onboarding skilled team members to accelerate development and maintain project timelines.
  • Created reusable Terraform modules across multiple Git repositories, streamlining AWS infrastructure management and deployment.
  • Developed and deployed ASP.NET 8 serverless APIs via AWS Lambda, significantly improving back-end responsiveness and scalability.
  • Directed front-end development using React, TypeScript, and Material UI, achieving cohesive and user-friendly interfaces for the admin panel and LIMS.
  • Configured and maintained CI/CD pipelines with Azure DevOps, reducing deployment times and enhancing team productivity.
  • Ensured secure and efficient data management using PostgreSQL and Redis hosted on AWS RDS, optimizing database performance and reliability.
  • Participated actively in UI/UX design processes, ensuring alignment between technical architecture and user experience objectives.
  • Integrated AWS IAM, Amazon S3, and Fargate to achieve a comprehensive, secure infrastructure supporting high availability and optimal performance.
Technologies: Artificial Intelligence (AI), Technical Leadership, React, C#, TypeScript, JavaScript, Material UI, OpenAI, Prompt Engineering, SQL, AI Prompts, Cursor AI, JetBrains Rider, Team Management, Team Mentoring, ASP.NET Core 8, Amazon Web Services (AWS), Terraform Cloud, Terraform, AWS Lambda, Serverless, Serverless Architecture, Entity Framework, Docker, Azure DevOps, Continuous Integration (CI), Continuous Delivery (CD), Single Sign-on (SSO), SaaS, Startups, Recharts, AI Tools, UI Design, Amazon API Gateway, Infrastructure as Code (IaC), Amazon Aurora, Code Review, Code Refactoring, OpenAI API, Infrastructure, Lambda Architecture, Vite, Redis, Software as a Service (SaaS), Leadership, Event-driven Architecture, Content Delivery Networks (CDN), Lighthouse, AI Integration, UI Testing, Team Leadership, DevOps, Dashboards, Zustand, Application State Management, Cloud Architecture, Back-end Architecture, Back-end Development, Claude, ChatGPT, Server Sent Events (SSE), System Architecture, Claude Code, Anthropic, AI Engineering, Solution Architecture, Web UI Design, Amazon EC2, HTTP, Middleware, Scalable Web Services, Scalability, Software Design, Model Context Protocol (MCP), OAuth 2, Generative Artificial Intelligence (GenAI), Multitenancy, Product Management, LLM Integration, Startup Consulting, Technical Project Management, UX Design, Amazon Elastic Container Service (ECS), Multi-tenant Architecture, Zod, Deployment, Relational Databases, System Design, Systems Design, Technical Documentation, React Testing Library, Microsoft Excel, Refactoring, Document Processing, Multi-tenant SaaS, HIPAA, Technical Architecture, Claude API

Tech Lead

2023 - 2025
HubSpot
  • Led a front-end team of three engineers, successfully guiding the team through formation stages and establishing effective workflows and collaboration practices.
  • Built AI-driven back-end services in Java, including designing prompt engineering solutions and implementing tools for efficient prompt evaluation.
  • Developed a performance-intensive KPI dashboard (CCOM), significantly optimizing data loading to enhance page load speed across desktop and mobile.
  • Engineered complex front-end features from custom designs, resulting in seamless UI/UX with detailed, interactive charts and advanced filtering capabilities.
  • Facilitated integration with the platform team, enabling the front-end team to independently resolve blockers and directly contribute to shared development tools.
  • Delivered critical CRM front-end features rapidly, consistently meeting high-quality standards and enhancing user experience.
  • Managed team priorities strategically during complex projects, maintaining clarity and focus, which significantly improved team productivity and alignment.
Technologies: Artificial Intelligence (AI), Technical Leadership, React, Next.js, Material UI, Java, Recharts, Highcharts, TypeScript, OpenAI, Llama 3, Prompt Engineering, AI Prompts, Cursor AI, JetBrains Rider, SQL, Team Management, Team Mentoring, JWT/AUTH, Large Language Models (LLMs), AI Tools, UI Design, Agentic AI, AI Agents, Code Review, Code Refactoring, OpenAI API, Infrastructure, Vite, Apache Kafka, Distributed Systems, Event-driven Design (EDD), Software as a Service (SaaS), Leadership, Event-driven Programming, Event-driven Architecture, Large Data Sets, Snowflake, Generative Artificial Intelligence (GenAI), Vector Databases, Server-side Rendering (SSR), Lighthouse, AI Integration, UI Testing, Team Leadership, Retrieval-augmented Generation (RAG), DevOps, Dashboards, Application State Management, Back-end Architecture, Back-end Development, n8n, Claude, ChatGPT, Server Sent Events (SSE), System Architecture, Claude Code, Anthropic, AI Automation, AI Engineering, Solution Architecture, Web UI Design, HTTP, Middleware, Scalable Web Services, Scalability, Software Design, Model Context Protocol (MCP), Agentic RAG Systems, Cloud Architecture, Multitenancy, LLM Integration, Technical Project Management, UX Design, Zod, Relational Databases, React Testing Library, Data Engineering, Open-source LLMs, Document Processing, Model Evaluation, Multi-tenant SaaS, Technical Architecture, Claude API

Senior Full-stack Developer

2023 - 2024
CertifyOS
  • Implemented a redesign of the Provider Details page within a Toptal Team, reducing total development time by 50% by creating a reusable table component using MUI Datagrid with inline editing and validation.
  • Executed end-to-end testing using Cypress for the newly developed reusable table component, ensuring its functionality and reliability.
  • Enhanced efficiency by setting up API client code generation with RTK Query code generation tool, resulting in a 30% reduction in front-end development time as developers no longer need to define new functions and models for API methods manually.
  • Strengthened the reliability and robustness of the NestJS API by adding a comprehensive suite of unit tests, ensuring code integrity and minimizing potential regressions.
  • Improved database entities using TypeORM by implementing enums where appropriate, enhancing data consistency and query efficiency.
  • Actively participated in team collaboration activities, supporting team members, conducting code reviews, and contributing improvement ideas to enhance overall project quality and efficiency.
Technologies: JavaScript, TypeScript, Next.js, NestJS, Google Cloud Platform (GCP), Jest, Unit Testing, Material UI, E2E Testing, React, Web UI, RTK Query, RTK Query Code Generation, Swagger, TypeORM, SOLID Principles, Automated Testing, Cypress, SaaS, Google Cloud, JWT/AUTH, UI Design, Code Review, Code Refactoring, GitHub Actions, Infrastructure, Vite, Lighthouse, UI Testing, Legal Technology (Legaltech), DevOps, Application State Management, Back-end Development, HTTP, Middleware, Zod, Relational Databases, React Testing Library, Refactoring, Multi-tenant SaaS

Lead Front-end React Developer

2023 - 2024
Syntracts, Inc.
  • Developed a cutting-edge website for a generative AI tool, utilizing Next.js, React, and TypeScript, ensuring pixel-perfect precision and seamless user experience.
  • Completed the entire website development within a tight deadline of three weeks, optimizing project efficiency and exceeding client expectations.
  • Collaborated closely with clients, back-end developers, and designers to understand project requirements and deliverables.
  • Implemented responsive design principles, ensuring optimal performance on both desktop and mobile platforms.
  • Integrated authentication and sharing features, enhancing user accessibility and collaboration.
  • Incorporated Google Analytics to track user behavior and website performance, enabling data-driven decision-making and iterative improvements.
Technologies: React, CSS, Next.js, JavaScript, TypeScript, Flowbite, Google Analytics 4 (GA4), Google Tag Manager, Responsive UI, Web UI, Mobile UI, SOLID Principles, Automated Testing, Cypress, Authentication, SaaS, JWT/AUTH, Large Language Models (LLMs), UI Design, Code Review, Code Refactoring, GitHub Actions, Infrastructure, Vite, Software as a Service (SaaS), Leadership, Server-side Rendering (SSR), Lighthouse, UI Testing, Legal Technology (Legaltech), DevOps, Application State Management, n8n, Web UI Design, HTTP, Middleware, LLM Integration, Zod, Tailwind UI, Deployment, Relational Databases, React Testing Library

Lead Full-stack Developer

2023 - 2023
Realtyshoot
  • Developed an app that connects real estate owners with photographers and stagers. It lets them find and choose the photographer and schedule the photo session.
  • Fixed multiple problems including the broken Stripe integration.
  • Managed one mid-level front-end developer using Jira as a task management tool. Conducted regular code reviews.
  • Improved the development setup with a Docker Compose file for local development.
Technologies: Stripe, NestJS, React, TypeScript, Prisma, Docker, Amazon Web Services (AWS), Amazon S3 (AWS S3), JavaScript, CSS, HTML, Tailwind CSS, Monorepos, PostgreSQL, Node.js, SQL, REST, RDBMS, Vercel, ChatGPT, Startups, Project Management, API Development, Cloud, Material Design, Web UI, Web UX, Redux Toolkit, GraphQL, Data Visualization, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, DevOps, SOLID Principles, Authentication, WebSockets, JWT/AUTH, UI Design, Code Review, Code Refactoring, Stripe API, Infrastructure, Vite, Leadership, Server-side Rendering (SSR), Lighthouse, UI Testing, Legal Technology (Legaltech), Application State Management, Webhooks, HTTP, Middleware, Tailwind UI, Relational Databases, Refactoring

Senior Node.js Engineer

2023 - 2023
Digible Inc.
  • Developed a minimum viable product (MVP) that automates content posting on Facebook and Instagram, enhancing content delivery efficiency.
  • Designed multiple content templates for Facebook and Instagram, enriching the MVP's capabilities for diverse posting needs.
  • Engineered a rule-based algorithm to generate new social media content, expanding automated content variety.
  • Refined TypeScript settings to enable null reference error checking, enhancing code robustness in the existing project.
  • Authored a comprehensive technical design document outlining the content-generation process, serving as a blueprint for future development and team member onboarding.
  • Automated the development workflow by setting up Github Actions, streamlining build and deployment processes during pull requests.
  • Standardized coding practices by configuring ESLint according to the Airbnb JavaScript Style Guide and fixed related errors.
  • Collaborated with cross-functional teams to gather requirements and feedback, ensuring the MVP aligned with organizational goals and user needs.
  • Conducted rigorous testing and debugging of the MVP, contributing to reliable uptime and minimal rollbacks on deployments.
Technologies: Node.js, NestJS, PostgreSQL, JavaScript, TypeScript, TypeORM, Sequelize, Google Cloud, GitHub, Axios, ESLint, UI Bakery Copilot, Amazon Web Services (AWS), Minimum Viable Product (MVP), Architecture, Google Cloud Platform (GCP), Express.js, Postman, Full-stack Development, ECMAScript (ES6), REST, RDBMS, ChatGPT, Startups, API Development, Cloud, Web UI, Web UX, Redux Toolkit, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, Docker, SOLID Principles, SaaS, JWT/AUTH, Firebase, Code Review, Code Refactoring, GitHub Actions, Application State Management, Back-end Architecture, Back-end Development, HTTP, Middleware, Relational Databases, Refactoring

Senior Full-stack Developer

2022 - 2023
GeneDx
  • Completed a 1.5-year migration project successfully, transitioning from AngularJS to React with TypeScript.
  • Implemented new website layouts based on Figma designs, ensuring a modern and intuitive user experience.
  • Developed a comprehensive component library, adhering to Figma designs, for seamless integration into the website.
  • Reverse-engineered legacy code, enhancing maintainability and scalability by migrating it to a clean and efficient React codebase.
  • Expertly managed a complex ordering flow with multiple steps, sub-steps, and fields, including real-time validation and status tracking.
  • Implemented data persistence functionality, enabling users to reload the page without losing entered data, enhancing user convenience.
  • Integrated React application and standalone React components into the CRM system.
  • Successfully set up advanced event tracking using GA4 (Google Analytics 4) and designed a comprehensive technical schema leveraging GTM (Google Tag Manager) to optimize user experience insights and enhance digital strategy.
Technologies: JavaScript, HTML5, CSS, .NET, React, TypeScript, MobX, AngularJS, SQL, Git, GitHub, Storybook, Figma, Swagger, REST APIs, C#, ASP.NET, Google Analytics, Multithreading, Docker, Docker Compose, Webpack, Handlebars, Linux, Amazon Web Services (AWS), Minimum Viable Product (MVP), Architecture, OAuth, B2C, Postman, Full-stack Development, Customer Relationship Management (CRM), Integration, ECMAScript (ES6), SCSS, Headless Commerce, Google Analytics 4 (GA4), Google Tag Manager, REST, RDBMS, API Development, Cloud, Web UI, Web UX, Redux Toolkit, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, SOLID Principles, Automated Testing, JWT/AUTH, UI Design, Code Review, Code Refactoring, GitHub Actions, Infrastructure, Lighthouse, UI Testing, Application State Management, Back-end Architecture, Back-end Development, HTTP, Middleware, Relational Databases, Refactoring

Senior Front-end Developer

2021 - 2021
Unilever
  • Implemented the designs of several screens with pixel-perfect accuracy.
  • Adjusted Material UI components to the design appearance using the theming approach.
  • Introduced React development best practices to the project.
Technologies: React, TypeScript, Material UI, Jest, JSS, Design Systems, Git, Formik, Yup, Pixel Perfect, GitHub, Full-stack, Windows, Front-end, Web Development, HTML, Responsive Web Design (RWD), User Experience (UX), User Interface (UI), UI Components, Web Applications, UI Libraries, Component Libraries, Front-end Architecture, Front-end Development, CSS3, Minimum Viable Product (MVP), Architecture, Full-stack Development, ECMAScript (ES6), SCSS, Material Design, Web UI, Web UX, Redux Toolkit, D3.js, Data Visualization, Charting, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, SOLID Principles, UI Design, Code Review, GitHub Actions, DevOps, Application State Management, HTTP, Middleware, Relational Databases

Senior Full-stack Developer

2021 - 2021
Yara
  • Developed an app that helps farmers create crop nutrition plans. The app gives you a recommendation on when and how much fertilizer you should apply. Users can view data in different formats like tables and charts and share the plan as a link or PDF.
  • Built an app that helps farmers keep track of the farm's sustainability. It calculates the CO2 and N emissions levels compared to benchmarks and gives users improvement suggestions.
  • Conducted interviews for junior, mid, and senior positions.
  • Demoed new features to other teams and stakeholders.
  • Investigated the best graph library for the project, prepared comparisons with showcases, and presented them to the team leads.
  • Worked as part of the development team following the Scrum process. Conducted onboarding sessions for newcomers.
Technologies: React, TypeScript, JavaScript, Node.js, NestJS, GraphQL, Apollo, PostgreSQL, Amazon Web Services (AWS), CircleCI, Git, Design Systems, Styled-components, Microservices, Cypress, E2E Testing, Jest, React-Intl, Urql, Lodash, Recharts, React Hook Form, ESLint, Visual Studio Code (VS Code), Axios, Sequelize, Puppeteer, Segment, Phrase, Charts, Figma, DevOps, GitHub, Full-stack, Windows, Front-end, REST APIs, Web Development, HTML, Next.js, Responsive Web Design (RWD), MERN Stack, API Integration, Architecture, APIs, User Experience (UX), User Interface (UI), UI Components, Storybook, Back-end, CI/CD Pipelines, Web Applications, UI Libraries, Component Libraries, Front-end Architecture, Front-end Development, CSS3, Multithreading, Express.js, Algorithms, Handlebars, Linux, Minimum Viable Product (MVP), Integration Testing, Postman, Full-stack Development, ECMAScript (ES6), SCSS, REST, API Gateways, RDBMS, API Development, Cloud, Web UI, Web UX, Redux Toolkit, D3.js, Data Visualization, Charting, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, SOLID Principles, Automated Testing, JWT/AUTH, UI Design, Code Review, Code Refactoring, Infrastructure, Lighthouse, UI Testing, Application State Management, Back-end Architecture, Back-end Development, HTTP, Middleware, Software Design, Relational Databases

Senior Full-stack Developer

2020 - 2020
ALLEYE
  • Implemented a web service called ALLEYE from scratch, helping organize and manage the instrument validation process in the health industry.
  • Prepared the architecture and implemented the website that consists of an ASP.NET Core REST API, a React SPA, and an SQL server database hosted in a dockerized Linux container on AWS.
  • Implemented features such as a dashboard with plenty of charts, audit trail, authentication and authorization with roles and permissions (using ASP.NET Core Identity and JWT), recurring jobs with Hangfire, and screen lockout after some time of inactivity.
  • Transformed the client's requirements into working solutions. Worked following the Scrum methodology, with daily scrums, grooming, planning sessions, and estimates, managing a small team of developers.
  • Configured CI/CD with test environment and auto deployments with Azure DevOps and AWS ECS.
Technologies: REST APIs, Visual Studio Code (VS Code), Database Design, Databases, HTML5, Swagger, AWS IAM, Cross-browser Compatibility, JSON Web Tokens (JWT), Data Visualization, Docker, Amazon Elastic Container Registry (ECR), Amazon Elastic Container Service (ECS), Amazon EC2, Amazon Web Services (AWS), Azure DevOps, Git, Lodash, Axios, React Router, Yup, Formik, React-Intl, Material UI, Recharts, CSS, JSS, HTML, JavaScript, TypeScript, React Hooks, React Redux, Redux, Single-page Applications (SPAs), React, Code First, SQL, SQL Server 2017, Serilog, AutoMapper, FluentValidation, LINQ, Entity Framework Core, Hangfire, Identity, MediatR, ASP.NET Core, .NET Core, C#, REST, Charts, DevOps, Transact-SQL (T-SQL), Visual Studio, Full-stack, C#.NET, .NET, Windows, SQL Server Management Studio (SSMS), Front-end, Web Development, AWS Lambda, Figma, Responsive Web Design (RWD), API Integration, Architecture, APIs, User Experience (UX), User Interface (UI), UI Components, Back-end, CI/CD Pipelines, Web Applications, UI Libraries, Component Libraries, Front-end Architecture, Front-end Development, SaaS, CSS3, Multithreading, Algorithms, Linux, Minimum Viable Product (MVP), OAuth, Integration Testing, Postman, Full-stack Development, Customer Relationship Management (CRM), ECMAScript (ES6), SCSS, RDBMS, Startups, Project Management, Inventory Management, API Development, Cloud, Material Design, Web UI, Web UX, Amazon RDS, Redux Toolkit, PostgreSQL, D3.js, Charting, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, SQL Management Studio, SOLID Principles, Automated Testing, Authentication, JWT/AUTH, UI Design, Code Review, Code Refactoring, Terraform, ECS, Infrastructure, Software as a Service (SaaS), Content Delivery Networks (CDN), Lighthouse, UI Testing, Dashboards, Application State Management, Back-end Architecture, Back-end Development, Solution Architecture, HTTP, Middleware, Software Design, Startup Consulting, Technical Project Management, Deployment, Relational Databases, Technical Architecture

Senior Full-stack Developer

2019 - 2020
Freelance
  • Created a React application that generates an HTML page based on data provided in the JSON file, then converted this page into a PDF file using headless Chrome.
  • Refactored and added new functionality to websites written in AngularJS, including logic and styles.
  • Developed a data parser that took .txt files as input, then red-lined and decoded them from Base64 to parsed JSON, calculated all needed data, and produced a new file with results.
  • Communicated with clients from the US, India, and UAE.
  • Analyzed requirements, provided estimates, and met deadlines.
Technologies: REST APIs, React-Bootstrap, Visual Studio Code (VS Code), Sass, Less, Serverless, Database Design, Databases, Node.js, HTML5, Cross-browser Compatibility, Pixel Perfect, C#, AngularJS, JavaScript, CSS, HTML, React, DevOps, Visual Studio, SQL, Git, GitHub, Full-stack, Windows, Front-end, Web Development, Responsive Web Design (RWD), Bootstrap, Architecture, User Experience (UX), User Interface (UI), UI Components, Back-end, CI/CD Pipelines, Web Applications, Front-end Architecture, Front-end Development, Heroku, Minimum Viable Product (MVP), Full-stack Development, ECMAScript (ES6), SCSS, Prisma, Tailwind CSS, REST, Startups, Material Design, Web UI, Web UX, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Estimations, SOLID Principles, Code Review, Application State Management, HTTP, Middleware, Relational Databases

Senior Full-stack Developer

2019 - 2020
e-Boks A/S
  • Prepared the architecture for a new product that consisted of several services and a SPA. Created user stories, provided estimates, and built the tracking progress.
  • Conducted about 20 interviews for the project so far.
  • Created projects from scratch and deepened my knowledge of the security domain.
  • Refactored and introduced unit testing in products.
Technologies: REST APIs, Visual Studio Code (VS Code), .NET Core, Sass, Less, Database Design, Databases, Test-driven Development (TDD), Node.js, Jira, HTML5, Swagger, Amazon S3 (AWS S3), Amazon CloudFront CDN, MySQL, Angular, OAuth 2, Cross-browser Compatibility, Unit Testing, NUnit, Moq, Pixel Perfect, TeamCity, Octopus Deploy, TFS, LINQ, Entity Framework, Datadog, Microsoft SQL Server, CSS, JavaScript, React, ASP.NET Web API, C#, Transact-SQL (T-SQL), Visual Studio, SQL, Git, Full-stack, C#.NET, .NET, Windows, SQL Server Management Studio (SSMS), Front-end, Web Development, HTML, Web Performance Optimization (WPO), Responsive Web Design (RWD), API Integration, Architecture, APIs, User Experience (UX), User Interface (UI), UI Components, Back-end, CI/CD Pipelines, Web Applications, Cryptography, Front-end Architecture, Front-end Development, Multithreading, Algorithms, Handlebars, Linux, Amazon Web Services (AWS), Minimum Viable Product (MVP), Integration Testing, Postman, Full-stack Development, Customer Relationship Management (CRM), ECMAScript (ES6), SCSS, REST, RDBMS, API Development, Cloud, Web UI, Web UX, Redux Toolkit, Active Server Pages (ASP), ASP.NET Core MVC, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, DevOps, Docker, SQL Management Studio, SOLID Principles, Automated Testing, Authentication, JWT/AUTH, Code Review, Code Refactoring, UI Testing, Application State Management, Back-end Architecture, Back-end Development, HTTP, Middleware, Relational Databases, Refactoring

Middle Full-stack Developer

2016 - 2019
JustAnswer
  • Led a subproject, including overseeing the SDD preparation, creating user stories, providing estimates, and tracking progress.
  • Spearheaded a data quality initiative within the team. The primary goal was to find problems with tracking, introduce solutions and implement them, and ensure correctness via integration and Selenium tests.
  • Refactored many elements, writing dozens of unit, integration, and Selenium tests.
  • Conducted extensive A/B testing, including implementing experiments that required several versions of web pages, which differed in UI and functionality. Compared the conversion rate and other metrics of those pages.
  • Became deeply familiar with the Scrum methodology here.
  • Established and ran code reviews for my teammates.
Technologies: REST APIs, Visual Studio Code (VS Code), Sass, Less, Database Design, Databases, Test-driven Development (TDD), Node.js, HTML5, Cross-browser Compatibility, Unit Testing, NUnit, Moq, Pixel Perfect, Git, LINQ, Entity Framework, Redis, Dynatrace, Microsoft SQL Server, React, CSS, ASP.NET MVC, Selenium, JavaScript, C#, Transact-SQL (T-SQL), Visual Studio, SQL, Full-stack, C#.NET, .NET, Windows, SQL Server Management Studio (SSMS), Front-end, Web Development, HTML, Web Performance Optimization (WPO), Responsive Web Design (RWD), API Integration, Architecture, APIs, User Experience (UX), User Interface (UI), UI Components, Back-end, CI/CD Pipelines, Search Engine Optimization (SEO), Web Applications, Front-end Architecture, Front-end Development, Multithreading, Algorithms, Handlebars, Integration Testing, Postman, Full-stack Development, ECMAScript (ES6), SCSS, Animation, REST, RDBMS, API Development, Web UI, Web UX, Active Server Pages (ASP), ASP.NET Core MVC, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, Software Architecture, Estimations, A/B Testing, SEO Tools, First Contentful Paint (FCP), SQL Management Studio, SOLID Principles, Automated Testing, JWT/AUTH, Code Review, Code Refactoring, Lighthouse, UI Testing, Back-end Architecture, Back-end Development, HTTP, Middleware, Cloudflare, Relational Databases, Refactoring

Junior Full-stack Developer

2014 - 2016
ByteAnt
  • Developed new web pages, including writing styles, JavaScript, database queries, unit tests, and more.
  • Optimized the performance of SQL queries via stored procedure optimization and database denormalization, which reduced the load time from 30 seconds to 100 milliseconds.
  • Became experienced with ASP.NET MVC, HTML, CSS, JavaScript, jQuery, Angular, Microsoft SQL Server, Elasticsearch, Entity Framework, LINQ, SVN, Git, and TeamCity.
Technologies: Database Design, Databases, PostgreSQL, Elasticsearch, Cross-browser Compatibility, Unit Testing, NUnit, Moq, Pixel Perfect, Git, Subversion (SVN), LINQ, Entity Framework, Microsoft SQL Server, jQuery, JavaScript, CSS, HTML, ASP.NET MVC, C#, AngularJS, Transact-SQL (T-SQL), Visual Studio, SQL, Full-stack, C#.NET, .NET, Windows, SQL Server Management Studio (SSMS), Front-end, REST APIs, Web Development, Web Performance Optimization (WPO), Responsive Web Design (RWD), API Integration, APIs, User Experience (UX), User Interface (UI), Back-end, Web Applications, Front-end Architecture, Front-end Development, Algorithms, Integration Testing, Postman, Full-stack Development, SCSS, REST, NoSQL, RDBMS, API Development, Web UI, Web UX, VBScript, Active Server Pages (ASP), ASP.NET Core MVC, Object-oriented Programming (OOP), Software Design Patterns, Best Practices, First Contentful Paint (FCP), SQL Management Studio, SOLID Principles, JWT/AUTH, Code Review, Code Refactoring, UI Testing, Back-end Architecture, Back-end Development, HTTP, Middleware, Relational Databases, Visual Basic 6 (VB6), Refactoring

Experience

Briefly

https://www.brieflywealth.com/
Briefly is an AI-powered wealth management CRM that helps financial advisors prepare for client meetings by turning uploaded PDF statements, meeting notes, and synced client emails into a structured, 8-section "brief" covering portfolio summary, action items, tax considerations, client sentiment, and more. The stack is a NestJS 11 + Prisma + PostgreSQL API, a React 19 + RTK Query client, and an AWS production environment (ECS Fargate, RDS, ALB, S3, CloudFront, Cognito) provisioned entirely through Terraform. I joined after an AI-generated prototype delivered by the client had stalled — the core generation pipeline was broken, the multi-file upload failed, and large parts of the UI were placeholders. I audited the system end-to-end, owned the back-end LLM pipeline (OpenRouter + Langfuse prompt versioning + Zod validation), fixed critical front-end flows, hardened the Terraform/GitHub Actions deployment pipeline, and shipped a working end-to-end demo that real advisors can use.

Insights

https://www.pcienergysolutions.com/about/pci-insights/
I worked on a web-based data visualization application that initially relied on Apache Superset for analytics and dashboard rendering. My role focused on evolving the product into a fully self-contained solution with its own visualization and dashboarding capabilities. I led a major refactoring of the React codebase, reorganizing it around feature-driven architecture, migrating from Create React App to Vite, and introducing full TypeScript coverage to improve maintainability and reliability.

I significantly improved performance by reducing page load times by approximately 10x through the introduction of RTK Query–based caching, concurrent API requests, optimized API payloads, and proper HTTP caching configuration on the NGINX layer. I implemented a client-owned visualization layer using extensible chart and table components, replacing Superset-dependent rendering. I also developed a flexible dashboard system with dynamic grid layouts and multi-tab support, allowing users to create complex analytical views. Finally, I implemented data migration scripts using Node.js and Prisma ORM to transfer existing Superset data into the application’s own database, completing the transition away from 3rd-party BI tooling.

CCOM Dashboard

CCOM Dashboard was a high-performance internal KPI dashboard developed for HubSpot. It focused on delivering complex business insights through beautiful, interactive visualizations. Built with React, TypeScript, Next.js, MUI, and Recharts, the application presented detailed tables and charts with support for advanced filtering and data breakdowns.

I was solely responsible for building the front end from scratch, collaborating closely with the design studio through frequent iteration and joint planning sessions. Data was loaded via GraphQL and React Query, with comprehensive integration into Cube APIs using dynamic filters and dimensions.

To ensure exceptional performance, I implemented lazy loading, memoization, and virtualization strategies. I also created a custom API interceptor that intelligently delayed and batched requests, resolving HTTP parallelism issues under heavy data loads.

The dashboard was fully responsive and optimized for both desktop and mobile. It became an internal success story, with over 300 users in the first week and excellent feedback from stakeholders.

Realtyshoot

https://realtyshoot.com/
A web platform leveraging cutting-edge technologies such as React, NestJS, TypeScript, and PostgreSQL. This innovative website serves as a robust marketplace connecting real estate proprietors with a network of professional photographers, photo editors, and staging experts. Its primary mission is to empower property owners to showcase their listings with captivating imagery, ultimately enabling them to achieve optimal selling prices in the real estate market.

Fiona Posts

https://digible.com/
A NestJS and React-based application that automates real estate content posting on Google business platform, Facebook and Instagram.

I've developed a minimum viable product (MVP) that automates content posting on Facebook and Instagram, enhancing content delivery efficiency. I also designed multiple content templates for Facebook and Instagram, enriching the MVP's capabilities for diverse posting needs.

Provider Portal

https://www.genedx.com/
The GeneDx Provider Portal provides a fast, efficient, secure, and HIPAA-compliant way for healthcare providers to order tests and access their patients' test result reports.

In a 1.5-year migration project for GeneDx's Provider Portal, I led the transition from AngularJS to React with TypeScript. I designed new Figma-based layouts, created a robust component library, and reverse-engineered legacy code for a seamless migration. The complex ordering flow was reimagined, featuring real-time validation, a dynamic side menu, and data persistence, resulting in an intuitive and efficient user experience. The successful project cemented GeneDx's position as a leader in genetic and genomic testing services.

Atfarm

https://www.at.farm/
A React-based application that helps farmers create crop nutrition plans. The app recommends when, where, and how much fertilizer you should apply. A user can import soil analysis results from many laboratories across different countries. The data can be presented in different formats, e.g., tables, charts, and so on, and can be shared via email as a link or PDF file.
Moreover, it keeps track of the farm's sustainability. It calculates the CO2 and N emissions levels compared to benchmarks and suggests improvements.

ALLEYE CMMS Software

https://www.apsinco.com/alleye-cmms-software
I developed the website, which is used as a CMMS system to manage instrument validation.
It is written in C#, React, and TypeScript and uses SQL server as the database.
I created everything from scratch, which included setting up CI/CD on Azure DevOps with a Git repo and automatic deployments to AWS ECS.
The codebase is covered with unit tests and end-to-end tests using Cypress.io.
Later on, I managed a small team of developers.

JustAnswer

I developed a web service that allows people to get expert's answers in different areas for a small price. It consists of a website (Justanswer.com) where you can ask your own question or find an already-answered one.

e-Boks

https://www.e-boks.com/danmark/da/
I created a web service for the secure transmission and storage of documents introduced to all residents in Denmark. It consists of a website (E-boks.com/danmark/da) and numerous private services. It also has mobile apps for Android and iOS, which provide all primary functionality.

Mechanic Advisor

I developed a web service that connects people to auto repair shops. It consists of a website (Mechanicadvisor.com) where you can search through a huge list of shops as a customer or manage your business as a shop owner.

HTML to PDF Conversion

I created a React application that generates an HTML page based on data provided in a JSON file. Then this page can be converted to a PDF file using headless Chrome.
The source code can be found here: https://github.com/likerrr777/PrintHtmlToPdf

Education

2012 - 2018

Master's Degree in Applied Mathematics and Informatics

Ivan Franko National University - Lviv, Ukraine

Certifications

MAY 2026 - PRESENT

AI Agents with LangChain and LangGraph

Udemy

DECEMBER 2025 - DECEMBER 2028

AWS Solutions Architect Associate

Amazon Web Services

MAY 2025 - PRESENT

Generative AI for Everyone

DeepLearning.AI

MAY 2025 - PRESENT

ChatGPT Prompt Engineering for Developers

DeepLearning.AI

DECEMBER 2020 - PRESENT

NestJS Zero to Hero — Modern TypeScript Back-end Development

Udemy

Skills

Libraries/APIs

MediatR, AutoMapper, Recharts, React-Intl, Formik, Yup, React Router, Lodash, REST APIs, React, LINQ, Moq, Entity Framework, Node.js, React Redux, React Hook Form, Handlebars, API Development, D3.js, Flowbite, React Query, Zod, React Testing Library, MobX, Highcharts, OpenAI API, Playwright, Claude API, jQuery, Serilog, Urql, Puppeteer, YouTube API, Stripe, Stripe API, Chart.js, AG Grid, Nylas API

Tools

Visual Studio, Amazon Elastic Container Service (ECS), Sequelize, Git, GitHub, SQL Management Studio, Webpack, Figma, Postman, Prisma, ChatGPT, Redux Toolkit, RTK Query, Terraform, Claude Code, TanStack Router, JSS, Amazon CloudFront CDN, Hangfire, Amazon Elastic Container Registry (ECR), Jira, Google Analytics, Docker Compose, AI Prompts, Lighthouse, Claude, Microsoft Excel, Dynatrace, TFS, TeamCity, AWS IAM, Subversion (SVN), RabbitMQ, CircleCI, JetBrains Rider, Superset, Vitest, AWS Fargate, Amazon CloudFront, n8n, Amazon Cognito, Shadcn, Shadcn UI, Logging

Languages

GraphQL, Transact-SQL (T-SQL), CSS, Sass, Less, TypeScript, JavaScript, HTML, HTML5, SQL, C#, C#.NET, CSS3, ECMAScript (ES6), SCSS, Active Server Pages (ASP), Python, VBScript, Java, Snowflake, Visual Basic 6 (VB6)

Frameworks

ASP.NET Web API, Redux, NestJS, Cypress, NUnit, ASP.NET, ASP.NET Core, Entity Framework Core, JSON Web Tokens (JWT), Swagger, OAuth 2, Material UI, .NET, .NET Core, Jest, Next.js, Express.js, Tailwind CSS, ASP.NET Core MVC, LangGraph, ASP.NET MVC, Selenium, React-Bootstrap, Bootstrap, AngularJS, Angular

Paradigms

REST, FluentValidation, Code First, Unit Testing, Microservices, E2E Testing, Automated Testing, DevOps, Web Performance Optimization (WPO), Responsive Web Design (RWD), Object-oriented Programming (OOP), Best Practices, Code Refactoring, Back-end Architecture, Web UI Design, Model Context Protocol (MCP), UX Design, Refactoring, Azure DevOps, Database Design, Test-driven Development (TDD), Search Engine Optimization (SEO), Serverless Architecture, UI Design, Lambda Architecture, Event-driven Programming, Event-driven Architecture, B2C, Continuous Integration (CI), Continuous Delivery (CD), Event-driven Design (EDD), DDoS

Platforms

Visual Studio Code (VS Code), Amazon Web Services (AWS), Windows, Amazon EC2, AWS Lambda, Software Design Patterns, Docker, Linux, Vercel, Twilio, Heroku, Google Cloud Platform (GCP), Firebase, Apache Kafka, Langfuse, Azure, Kubernetes, LangSmith, Ollama

Storage

PostgreSQL, SQL Server Management Studio (SSMS), SQL Server 2017, Databases, Microsoft SQL Server, RDBMS, Relational Databases, Amazon S3 (AWS S3), MySQL, Redis, Datadog, Elasticsearch, NoSQL, Google Cloud, Amazon Aurora, Amazon DynamoDB

Industry Expertise

Project Management

Other

Pixel Perfect, Cross-browser Compatibility, Single-page Applications (SPAs), Data Visualization, React Hooks, Axios, Front-end, TypeORM, Authentication, Authorization, APIs, Full-stack, Storybook, SOLID Principles, Multithreading, Apollo, Design Systems, Styled-components, ESLint, Charts, Web Development, MERN Stack, API Integration, Architecture, User Experience (UX), User Interface (UI), UI Components, Back-end, CI/CD Pipelines, Web Applications, UI Libraries, Component Libraries, Front-end Architecture, Front-end Development, SaaS, Algorithms, Minimum Viable Product (MVP), Integration Testing, Full-stack Development, Customer Relationship Management (CRM), Integration, API Gateways, Startups, Material Design, Web UI, Web UX, Charting, Software Architecture, Estimations, A/B Testing, First Contentful Paint (FCP), Responsive UI, Mobile UI, RTK Query Code Generation, Cursor AI, Artificial Intelligence (AI), Technical Leadership, Prompt Engineering, Performance, JWT/AUTH, Large Language Models (LLMs), AI Tools, Amazon API Gateway, Agentic AI, Code Review, GitHub Actions, Vite, Software as a Service (SaaS), Leadership, Generative Artificial Intelligence (GenAI), UI Testing, Dashboards, Application State Management, Cloud Architecture, Back-end Development, Server Sent Events (SSE), System Architecture, Anthropic, AI Engineering, Solution Architecture, Code Auditing, HTTP, Middleware, Scalable Web Services, Scalability, Software Design, Vibe Coding, LangChain, Multitenancy, Startup Consulting, Technical Project Management, Multi-tenant Architecture, Tailwind UI, Deployment, System Design, Systems Design, Technical Documentation, Multi-tenant SaaS, Technical Architecture, Identity, Serverless, PDF, Cryptography, OAuth, Headless Commerce, Animation, Monorepos, Google Analytics 4 (GA4), Google Tag Manager, Inventory Management, Cloud, Amazon RDS, Web Project Management, Terraform Cloud, OpenAI, Team Mentoring, Single Sign-on (SSO), Infrastructure as Code (IaC), AI Agents, ECS, Infrastructure, Content Delivery Networks (CDN), Server-side Rendering (SSR), AI Integration, Progressive Web Applications (PWAs), Team Leadership, Zustand, AI Automation, Agentic RAG Systems, Product Management, AI Agent Orchestration, LLM Integration, OXC (Oxlint), Cloudflare, Finance, Data Engineering, Open-source LLMs, Document Processing, Model Evaluation, HIPAA, Octopus Deploy, Team Management, Segment, Phrase, Chromium, Cryptocurrency, Applied Mathematics, UI Bakery Copilot, Web3, Crypto, Decentralized Finance (DeFi), SEO Tools, WebSockets, Llama 3, ASP.NET Core 8, Chatbots, Fine-tuning, Supervised Learning, Reinforcement Learning from Human Feedback (RLHF), Distributed Systems, Large Data Sets, Vector Databases, AG Charts, Apache Superset, React Grid Layout, AWS IAM Identity Center, Retrieval-augmented Generation (RAG), Legal Technology (Legaltech), Webhooks, Amazon Redshift, Fintech, AWS ECS Fargate, Load Balancers, Speech-to-Text (STT), Text-to-Speech (TTS), Optical Character Recognition (OCR)

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