Kostiantyn

Kostiantyn Dontsov
Full stack developer
Phone: [открыть контакты](см. выше в блоке «контактная информация») | Email: [открыть контакты](см. выше в блоке «контактная информация»)
Location: Winchester, United Kingdom | Open to relocation or remote
Portfolio: https://dontsov-dev.vercel.app/
LinkedIn: [открыть контакты](см. выше в блоке «контактная информация»)

A passionate Full Stack Developer with 1.5+ years of experience in building scalable web
applications using modern technologies such as React, Node.js, Nest.js, Express.js, PostgreSQL, MongoDB,
and AWS. Skilled in optimizing database performance, developing robust APIs, and delivering seamless
front-end experiences. Demonstrated expertise in Elasticsearch integration, CI/CD pipelines, unit testing,
and Agile methodologies. Known for strong problem-solving skills, adaptability, and the ability to thrive
in collaborative environments. Currently based in the United Kingdom, seeking a long-term opportunity
with a UK-based company to contribute to impactful projects and drive innovation.

KEY SKILLS:
Programming Languages: JavaScript, TypeScript, SQL, Python (basic)
Frameworks & Libraries: React, Next.js, Node.js, Express.js, Redux, React query, Nest.js
Databases: PostgreSQL, MongoDB, MySQL
Tools & Platforms: Docker, AWS, Elasticsearch, k6/Grafana
Testing: React Testing Library, Jest
Other Tools: Postman, GitHub, Bitbucket, Jira.
Soft skills: Problem-Solving, Communication, Time Management, Teamwork & Collaboration,
Adaptability, Critical Thinking, Attention to Detail, Quick learner.

EMPLOYMENT HISTORY:
Full Stack Developer
Meduzzen – Remote, Ukraine
July 2024 – Present
Developing a social network for an educational platform with real-time collaboration tools,
targeting over 100 daily active users. Contributed to the development of analytics and statistics
logic for a crypto trading dashboard.
• Designed and implemented, performance optimization, refactoring the backend code written
in Node.js/Express.js and Nest.js.
• Built and integrated reusable React components, hooks, services, and global state
management using Redux to deliver a seamless user experience in Next.js and vanilla React.
• Developed database migrations for PostgreSQL with TypeORM and for MongoDB, including
data migration scripts from MongoDB to PostgreSQL.
• Performed unit testing using Jest and React Testing Library, achieving over 70% code
coverage.
• Created stress testing scripts for API endpoints using k6 and Grafana, improving API stability
and reducing query execution time by 40%+.
• Integrated Elasticsearch for global search functionality, enabling multi-keyword queries with
optimized performance and real-time synchronization with Elasticsearch Cloud Store.
• Wrote unit tests for React components using Jest and React Testing Library.
• Collaborated in an Agile environment with developers and project managers to refine and
implement system features.
Full Stack Developer (Internship)
Digital Horizon AweGoo – Remote, Ukraine
May 2024 – July 2024
Contributed to a project using AWS Amplify and PostgreSQL to enhance backend functionality.
• Conducted code reviews and optimized performance across project modules.
• Developed backend components using AWS Amplify Gen 2, creating API endpoints, GraphQL
queries, and Lambda functions for automated requests to third-party APIs.
• Integrated a PostgreSQL database via AWS RDS, streamlining data retrieval and management.
• Implemented frontend functionality to efficiently fetch and display backend data.
• Deployed API endpoints using AWS API Gateway, enhancing system reliability and scalability.

Full Stack Developer
Self-employed/Volunteer – Remote
February 2023 – May 2024
Worked on diverse freelance and volunteer projects to expand technical skillset.
• Built responsive and visually appealing websites using HTML, CSS, and JavaScript, consistently
achieving 90–100 scores in Google Core Web Vitals.
• Developed a React application integrated with the OpenAI API, supported by a Node.js
backend and a PostgreSQL database.
• Created an interactive map app using the MapTiler API for dynamic location-based features.
• Built a full-stack e-commerce application with Next.js (TypeScript), Node.js/Express, and
PostgreSQL (via Prisma ORM), including secure image storage with AWS S3.
• Designed a Kanban board application with drag-and-drop support and GitHub issues
integration using the GitHub API.

ACHIEVEMENTS
• Database Query Optimization: Reduced data processing time by 40%+ through advanced
query tuning and backend performance enhancements.
• Global Search Implementation: Integrated full-text search with Elasticsearch, enabling
complex, multi-keyword queries across applications.
• Testing Excellence: Delivered high-quality unit tests using Jest and React Testing Library,
achieving 95%+ code coverage across both backend and frontend codebases.
• High-Performance Web Applications: Built responsive, accessible applications that
consistently scored 90–100 in Google Core Web Vitals, ensuring exceptional user experiences
and SEO performance.

EDUCATION AND QUALIFICATIONS:

National Academy of Law, Ukraine (2007–2012)
• Master’s degree in law
Certifications and Courses (2022-2024)
• Hillel IT School, Ukraine: TypeScript, React, Front-end Development, Node.js
• Codefinity: SQL, Next.js
• W3Schools, London: Web Development Bootcamp

REFERENCES
Available upon request