Looks like you have JavaScript disabled. For the full Twine experience, you will need to re-enable it.

I’m a senior full-stack engineer and tech lead with 16+ years of experience delivering high-performance web apps, SaaS platforms, and AI-powered products. I specialize in React, Next.js, Angular, and Node.js, plus scalable architectures, performance, and robust UX. I love turning complex business needs into production-ready systems and guiding teams to architectural excellence. I’m open to remote opportunities worldwide. I enjoy shaping product direction, mentoring engineers, and exploring AI integration, browser extensions, and data-driven experiences to drive real business value.…I’m a senior full-stack engineer and tech lead with 16+ years of experience delivering high-performance web apps, SaaS platforms, and AI-powered products. I specialize in React, Next.js, Angular, and Node.js, plus scalable architectures, performance, and robust UX. I love turning complex business needs into production-ready systems and guiding teams to architectural excellence. I’m open to remote opportunities worldwide. I enjoy shaping product direction, mentoring engineers, and exploring AI integration, browser extensions, and data-driven experiences to drive real business value.

Valentine Efimov

Full Stack Developer, Front-End Developer, Back-End Developer, +5





I’m a senior full-stack engineer and tech lead with 16+ years of experience delivering high-performance web apps, SaaS platforms, and AI-powered products. I specialize in React, Next.js, Angular, and Node.js, plus scalable architectures, performance, and robust UX. I love turning complex business needs into production-ready systems and guiding teams to architectural excellence. I’m open to remote opportunities worldwide. I enjoy shaping product direction, mentoring engineers, and exploring AI integration, browser extensions, and data-driven experiences to drive real business value.…I’m a senior full-stack engineer and tech lead with 16+ years of experience delivering high-performance web apps, SaaS platforms, and AI-powered products. I specialize in React, Next.js, Angular, and Node.js, plus scalable architectures, performance, and robust UX. I love turning complex business needs into production-ready systems and guiding teams to architectural excellence. I’m open to remote opportunities worldwide. I enjoy shaping product direction, mentoring engineers, and exploring AI integration, browser extensions, and data-driven experiences to drive real business value.

Available to hire

I’m a senior full-stack engineer and tech lead with 16+ years of experience delivering high-performance web apps, SaaS platforms, and AI-powered products. I specialize in React, Next.js, Angular, and Node.js, plus scalable architectures, performance, and robust UX. I love turning complex business needs into production-ready systems and guiding teams to architectural excellence.

I’m open to remote opportunities worldwide. I enjoy shaping product direction, mentoring engineers, and exploring AI integration, browser extensions, and data-driven experiences to drive real business value.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Language

Ukrainian

Fluent

English

Fluent

Russian

Fluent

Work Experience

Senior Full-Stack Engineer at Merly

September 1, 2024 - Present

Senior Full-Stack JS Staff Engineer responsible for platform-wide performance and quality improvements across Merly Mentor product. Led optimizations such as reducing page load times, introducing skeleton loaders, and implementing end-to-end tests to improve release confidence and user experience. Built Chakra UI-driven UI blocks and React/Next.js acceleration strategies, and led a team of engineers through full product lifecycle.

Lead Design and Delivery at Platflow.ai

May 1, 2023 - September 1, 2024

Led the design and delivery of the Platflow.ai MVP, an AI-powered SaaS for clinicians, including architecture, RBAC, activity tracking, and multi-tenant user management. Built full-stack features, re-architected components for rapid iteration, and established long-term platform strategy.

Full Stack Developer (PHP/JS) at Gameloft

June 1, 2010 - February 1, 2012

Built high-traffic internal tools across Gameloft’s global offices focused on reliability, data integrity, and real-time responsiveness. Implemented full-stack solutions using PHP/JS, designed scalable backend services and robust frontend interfaces.

Full Stack Developer (PHP/JS) at Gameloft, Ukraine

June 1, 2010 - February 1, 2012

Built high-traffic internal enterprise tools for thousands of daily users across Gameloft’s global offices, focusing on reliability, data integrity, and real-time responsiveness. Designed and implemented a company-wide Meeting Room Booking System; implemented authentication and role-based access control integrated with LDAP; pioneered SPA approaches using ExtJS/YUI to deliver desktop-class UX in the browser. Designed and optimized MySQL schemas for performance, implemented PHP business logic to support scheduling workflows, and collaborated with stakeholders to evolve product systems and a company-wide recruitment assessment platform.

Lead / Senior Front-End Developer (PHP/JS) at Gameloft, Ukraine

February 1, 2012 - February 1, 2018

Led design and delivery of mid-tier and front-end systems; managed cross-functional front-end and back-end teams of up to 12 engineers; established clean API contracts and robust data flows. Orchestrated SPA architecture during a period when single-page apps were emerging, delivering highly interactive, desktop-class UX in the browser. Implemented robust error handling, improved data validation, and contributed to architectural decisions that scaled across multiple products. Pioneered multi-team collaboration and contributed to global hiring assessments and platform initiatives.

Senior Full-Stack JS Engineer at Merly, USA

September 1, 2023 - September 1, 2024

Led design and delivery of the Platform Flow.ai MVP from scratch, a health-care Chrome/Edge extension enabling clinicians to retrieve patient information directly within their browser workflows, supporting early-stage fundraising.

Senior Full-Stack Engineer at Merly, USA

September 1, 2024 - Present

Drove platform-wide performance and quality improvements across the Merly Mentor product, contributing to both technical excellence and developer experience. Rebuilt the browser extension from vanilla JS to a React-based solution, achieving faster development cycles and a more robust UI. Implemented Redux for global state management, introduced Chakra UI for consistent UI primitives, and expanded unit and integration coverage to reduce regressions.

Senior Full-Stack JS Staff Engineer at Merly

September 1, 2024 - Present

Responsible for platform-wide performance and quality improvements across the Merly Mentor product, contributing to technical excellence and developer experience. Led initiatives to optimize data fetching and server rendering, introduced scalable front-end loaders, and elevated code quality through disciplined TypeScript usage and linting. Implemented end-to-end testing with Playwright and introduced a Chakra UI-based component library to accelerate feature development. Drove architectural decisions for multi-tenant AI-enabled SaaS platform design and defined long-term reliability strategies.

Lead/Senior Full Stack Engineer at Dinghy (UK)

February 1, 2018 - May 1, 2023

Designed and delivered front-end and back-end systems, including a modern SPA architecture, robust API layer, and multi-tenant data model. Introduced Jest and Playwright-based testing, implemented server-side rendering improvements, and drove overall code quality with strict TypeScript typing. Led cross-functional teams to align on architectural decisions and ensure timely delivery of features.

Principal Lecturer at International Solomonov University, Ukraine

September 1, 2011 - December 1, 2013

Taught core software development disciplines to undergraduate students, covering HTML, CSS, JavaScript, PHP, MySQL, and Zend Framework. Delivered practical training on SDLC, project management, and structured development methodologies, blending academic instruction with hands-on implementation.

Lead/Senior Full Stack Engineer at Merly

September 1, 2024 - Present

Drove platform-wide performance and quality improvements across the Merly product; reduced page load time from 3 seconds to 200ms by migrating data fetch to Next.js Server Components; achieved a 10x improvement in UI rendering via targeted optimization and component refactoring; introduced skeleton loaders and strict TypeScript typing; strengthened code quality with ESLint rules; expanded unit and integration test coverage to ~50%; implemented end-to-end testing with Playwright; introduced Redux for global state and Chakra UI for faster UI development; documented architecture in Jira/Confluence; implemented RBAC and multi-tenant architecture; improved deployment and observability.

Lead/Senior Full Stack Engineer at Platform.ai

September 1, 2023 - August 31, 2024

Led design and delivery of the Platform.ai MVP from scratch; built a Chrome/Edge browser extension enabling clinicians to retrieve patient information within their browser workflow to support early-stage fundraising. Architected full system: user lifecycle management, RBAC, activity tracking, and multi-tenant data isolation for an AI-driven SaaS platform. Rebuilt the browser extension from vanilla JS to React/Plasm o, achieving 10x development velocity; integrated Chakra UI v2; grew unit/integration test coverage to 80%; implemented Redux for global state; introduced AI assistant leveraging OpenAI; implemented SSO with corporate ID; implemented robust data access controls.

Full Stack Developer at Gameloft (Ukraine)

June 1, 2010 - February 1, 2012

Built high-traffic internal tools and dashboards for Gameloft studios; designed a company-wide Meeting Room Booking System; implemented LDAP-based authentication and role-based access control; migrated from legacy ExtJS/YUI to modern React/JS/TypeScript stack; contributed to backend services with Node.js; improved data models and real-time capabilities for internal workflows.