Sergii Severynov

I am a Frontend Software Engineer with multiple years of commercial experience in building applications of different complexity and also with the recent experience as a Team Lead. Being familiar with design patterns and domain driven design approaches I always follow the best practices of software development keeping my code clean, clear and scalable. My core technical stack is TypeScript and React/Next.js. I am interested in the development of high load, scalable and complex web applications. My passion is technical implementation and support of complex business needs, and I am eager to be a part of the decision making process.

• The all-in-one solution for global teams (Employee of Record and Payroll) - platform for hiring, managing and paying employees all over the world that provides the global businesses with the flexibility they need to build and grow their global teams.
  • I initially joined as a Senior Software Engineer in a front-end team consisting of five developers and later advanced to the role of Lead Software Engineer. My responsibilities encompass a variety of processes, including planning, mentoring, and development.
  • I am also progressively working with the tasks that involves Ruby on Rails both in the main app and the internal admin app.

Technical stack: Typescript, Ruby on Rails, React, Redux, TanStack Query, Material-UI, zod, CI/CD, Unit testing, REST API.

• Multitenancy and multi-language educational platform - main goal of this app is to empower children and students to explore, imagine and engage with ideas as they learn and to help parents or family members to communicate with children by participating in lessons, games, and even sharing story time.
  • I led the frontend team (4 developers) and managed the project in general (10 developers - FE, BE, QA). Together with the owner and CTO I was also responsible for the main technical decisions.
  • Project had a complex structure with 6 frontend apps and 7 backend microservices on Node.js and Python. Core features - live chat/video streams, live activities between users, multitenancy, internationalization, user generated content, moderation, kids accounts, payments, automated/manual tests, CI/CD, etc.
  • The most interesting and challenging part for me was the creation of the independent mini-apps (games, lessons) that were used across all apps (were moved to separate npm package at first, and later to a Next.js app) and the implementation of the live communication between users that allows them to play together in mentioned mini-games.

Technical stack: Typescript, React, Next.js, Redux, Apollo GraphQL, Material-UI, AWS, Web Sockets, npm packages, rollup, Docker, CI/CD, Unit testing, REST API.

• Cryptocurrency project - I was a technical lead in the project that includes landing page, staking app and admin panel.

Technical stack: Typescript, React, Next.js, Redux, SCSS, Web3, Blockchain, SEO, AWS (Route 53, EC2, S3, Cloudfront).

• Telehealth platform - A technology platform, which combines artificial intelligence, population insights, and predictive care navigation with a broad network of fully integrated healthcare services.
  • I led the frontend team (3 developers) initially and then switched to technical management of the project in general (3 developers - FE, BE, QA).
  • One of the most difficult tasks was to refactor the entire application to modern code standards in order to achieve scalability and maintainability. Also a lot of efforts were made to make the project fully accessible for people with disabilities.

Technical stack: Typescript, React, Redux, SCSS, Web Sockets, Unit testing, Web Accessibility.

• Marketplace startup - I developed frontend part of the MVP for the startup that allows users not only sell/buy/share goods and services but mainly valuable information. Core features - SSR, SEO, chat and user generated content.

Technical stack: Typescript, React, Next.js, Redux, Material-UI, Web Sockets, Unit testing, Web Accessibility, SEO, CI/CD, React Testing Library, Serverless.

• Interns code review and training, interviewing new candidates, communication with a clients and project management.

• Trips planning project - All-in-one solution for traveling around the world. Main goal is to store all trip related information in one place, starting from the accommodation/tickets search and ending with the photo sharing, etc.
  • Project had a lot of complex and interesting features - offline support with PWA, realtime updates, internationalization, dynamic forms, third-party services integration (Leaflet, Booking, Expedia, Viator etc.), events tracking, user-generated content and SEO optimization.
  • I was responsible for the full cycle frontend development including the main app and the landing page.

Technical stack: Typescript, React, Next.js, Redux, Firebase, Firestore, Material-UI, Web Sockets, Unit testing, PWA, SEO, CI/CD.

• Fintech project - Internal financial institution project specializing in short-term high-risk lending. I designed and built the frontend part from scratch, the core feature of this app is a complex dynamic forms generated from the configuration files and the injectable widget.

Technical stack: Typescript, React, Redux, Material-UI.

• Cryptocurrency news analysis project - custom web platform designed for scraping data from trusted websites and analyzing the popularity of cryptocurrency based on the collected information. The system continually analyzes data on all ICOs and presents the results in multiple hype charts.
  • My goal was to implement a new design and switch from the SPA (React) to the SSR (Next.js) in order to improve SEO. I also added PWA support.

Technical stack: Javascript, React, Next.js, Redux, SCSS, PWA.

• Speaker for internal offline and online meetups.
• Interns code review and training, interviewing new candidates.

• Local Insights - data provider focused on real-time real estate records, building permits, tax assessments and more. I was responsible for adding new features, design updates, bug fixes, code refactoring.

Technical stack: Javascript, React, Redux, Material-UI.

• Design and creating landing page for local air conditioning company.

• Bug fixing, design updates and minor improvements for the short-term projects.

• Negotiation, execution, signing and support of contracts for the sale of aviation goods and services.