Serhii Avdieiev
Offer Serhii work on your next project.
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Offer work 
Kyiv,
Ukraine
1 day 21 hours back
available for hire
3 Safes completed
28 days 14 hours back
2 clients
13 proposals made
age 40 years
on the service 11 months 21 days
Rating
Language proficiency level
Українська: fluent
English: advanced
CV
Passionate and talented information technologies professional, teacher and mentor with extensive experience in front-end development. I have product thinking mind set, and a knack for mentoring junior and middle developers. Besides my technical expertise I have demonstrated technical leadership with over 10+ years, established processes and was responsible for project architecture.
Frontend Engineer with over 18 years of experience building scalable, modern web applications — from robust UI components to performance-conscious architectures.
I am able to work independently, take ownership of features, and also comfortable doing research and exploratory work when needed.
My focus is on maintainable code, clean abstractions, and delivering real product value. I bridge implementation and product thinking, ensuring frontend work aligns with business goals and long-term sustainability.
Led Developer teams, driving task management. Strong and substantial expertise in the Frontend Development. Constantly gaining new skills and applying them on my Pet-projects. A good managerial background that allows me to act independently in the accordance with customer's projects goals. Expertise in modern JavaScript frameworks and programming approaches: React, Angular, and Vue.js.
I have advanced proficiency in General Web technologies (HTML5, CSS3 and TypeScript).
Worked in various teams to identify issues with velocity, delivery and quality and solve them. I am a self-motivated and reliable team player.
Overall Experience in development - more then 18 years
- Typescript (ES6+) - over 10 years
- Full-Stack development - 4 years
- React / Redux / Next - Over 5 years
- Angular / NgRx / RxJs / Angular material - over 4 years
- VueJS / VueStoreFront / Nuxt - over 3 years
- NodeJS - over 3 years
- Amazon Cloud Services / Google Cloud / Azure - over 7 years
- English - Upper-Intermediate
Skills and abilities
Programming
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Content Management Systems
from 18 USD for hour
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Databases & SQL
from 19 USD for hour
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Embedded Systems & Microcontrollers
from 19 USD for hour
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HTML & CSS
from 19 USD for hour
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Javascript and Typescript
from 19 USD for hour
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PHP
from 19 USD for hour
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Python
from 19 USD for hour
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Web Programming
from 19 USD for hour
Services
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AI Consulting
from 11 USD for hour
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Customer Support
from 18 USD for hour
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Data Processing
from 19 USD for hour
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Online Stores & E-commerce
from 19 USD for hour
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Website Development
from 19 USD for hour
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Website Maintenance
from 19 USD for hour
Promotion
Portfolio
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EFAQ — a platform for knowledge management and FAQ automation
Web Programming
EFAQ is a platform for knowledge management and FAQ automation, created to centralize, structure, and effectively deliver information in a convenient and scalable format. The main idea is simple: instead of answering the same questions over and over again, the system allows you to do it once — and do it right.
What problem does the project solve:
… Companies constantly face a stream of repetitive questions from users, clients, and even internal teams. This overloads support, slows down product development, and turns documentation into chaos.
EFAQ solves this by:
• structured knowledge storage
• centralized FAQ system
• reducing the load on support through self-service
• quick and convenient access to information
Key features:
• Dynamic FAQ management. Creation, editing, and organization of content with flexible hierarchy and categorization.
• Search and quick access to information.
• Scalable content architecture. The system withstands data volume growth without loss of performance.
• User-friendly UI/UX. Simple and intuitive interface focused on quick answers.
• Readiness for integration. Ability to embed into existing systems (CRM, web applications, support services).
Role in the project:
I acted as Lead Frontend / Full-stack Engineer and was responsible for:
• designing the frontend architecture from scratch
• building a scalable modular UI system
• implementing state management and data flow
• integrating with backend API
• optimizing performance
• ensuring accessibility (WCAG)
• technical leadership and making architectural decisions
• improving search and data structuring
Technical features:
• modern stack (React + TypeScript)
• component architecture
• API-driven approach (REST / GraphQL)
• performance optimization (lazy loading, code splitting)
• SEO optimization of content
• accessibility according to WCAG standards
Business value:
• reducing the load on support
• improving user experience
• faster user onboarding
• centralizing knowledge instead of chaos
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LuckyStakesCasino is a fully functional casino platform.
Web Programming
LuckyStakesCasino is a fully functional online casino platform designed to provide a high-performance, secure, and engaging user experience on both desktop and mobile devices. The platform combines interactive real-time gameplay, wallet management, and a bonus system within a scalable and maintainable architecture.
My role:
I served as Tech Lead / Senior Full-stack Developer, responsible for building the frontend architecture, making key technical decisions, and ensuring performance, scalability, and code quality.
…
Key achievements:
• Developed frontend architecture from scratch. Designed a scalable architecture with a clear modular structure, thoughtful state management, and reusable components. Made decisions regarding the use of SSR/CSR and rendering optimization for critical scenarios such as gameplay and financial transactions.
• High-performance UI for real-time gaming. Implemented responsive low-latency interfaces that ensure smooth interaction even under high load. Used lazy loading, code splitting, and resource optimization to improve Core Web Vitals.
• Integration of wallet and transaction systems. Implemented secure integration with backend services for deposits, withdrawals, and balance tracking. Ensured the reliability of financial transactions considering edge cases and error handling.
• Authentication and user management. Built secure authentication and session management flows. Implemented a role-based access model and protection against XSS and CSRF.
• Bonus and promotion system (frontend). Developed interfaces for bonuses, free spins, and promotional campaigns with the ability to flexibly customize according to business requirements.
• API integration and contract design. Collaborated on API contracts using OpenAPI/Swagger, improving interaction between frontend and backend teams.
• Performance optimization. Analyzed and eliminated bottlenecks using profiling. Optimized handling of large data volumes through memoization and virtualization.
• Created a UI component library. Built a unified design system to accelerate development and ensure interface consistency.
• CI/CD and code quality. Implemented coding standards, code review processes, and testing. Improved CI/CD processes for stable and predictable releases.
• Leadership and mentoring. Mentored developers, managed architectural decisions, and synchronized the technical aspects with business goals.
Main challenges:
• Ensuring real-time performance and low latency under high load
• Guaranteeing the reliability of financial transactions
• Balancing performance with complex UI/UX
• Building a flexible system for quickly adding new games and features
As a result, a scalable and high-performance platform was created, capable of serving a growing number of users while maintaining a high level of UX, security, and development speed.
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Genesis Game — browser-based interactive gaming platform
Web Programming
Genesis Game is a browser-based interactive gaming platform aimed at creating a fast, engaging, and visually appealing gaming experience directly in the browser.
At the core of the project is a combination of real-time interaction, modern frontend architecture, and performance optimization, which allows for a smooth gaming process without the need for installation or the use of resource-intensive clients.
… From a technical perspective, the platform focuses on:
• High-performance rendering using modern browser capabilities (Canvas/Web APIs)
• Adaptive and responsive UI that ensures a stable experience across different devices
• Scalable frontend architecture ready for expanding gaming mechanics
• Resource loading optimization that reduces latency and speeds up startup
• State management and real-time updates, critical for interactive gameplay
The project also demonstrates a strong emphasis on user experience, including smooth animations, intuitive controls, and a clean interface that minimizes barriers between the player and the game.
My role in the project:
I designed and implemented a scalable frontend architecture optimized for real-time interaction and high performance.
Key focuses:
• Building an extensible architecture that allows for adding new gaming mechanics without rewriting the core
• Ensuring low-latency interaction, critical for gameplay
• Utilizing performance optimization techniques (lazy loading, rendering optimization, efficient state management)
• Developing a modular UI system to support scalability and maintainability of the code
The main challenge was balancing between a rich interactive experience and the performance limitations of the browser, especially on different types of devices.
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BillionBahis — online platform for games
Web Programming
In the position of Lead/Senior Frontend Engineer, I was responsible for designing and implementing the frontend architecture of the platform, ensuring high performance in real-time data scenarios. The main focus was on optimizing rendering, processing live data, building a scalable and modular system, and ensuring stable operation under high load.
About the project BillionBahis — it is an online platform for betting and gaming.
… BillionBahis is a full-fledged online platform for betting and gambling, focused on a fast, stable, and user-friendly experience in the areas of sports betting, casino games, and live betting.
The main focus of the platform is performance, scalability, and real-time data handling, which is critically important in scenarios where decisions are made instantly, and delays directly affect user experience and financial transactions.
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Key features
1. Real-time betting
The platform supports live betting with constant odds updates. This required efficient data streaming and instant interface updates without sacrificing performance.
2. High-performance frontend architecture
Modern approaches to frontend application development were applied:
• fast rendering and smooth navigation
• effective state management for dynamic data (bets, odds, balance)
• code splitting and lazy loading for performance optimization
3. Scalable and modular architecture
The system is designed for:
• handling a large number of users simultaneously
• withstanding peak loads during major events
• quickly adding new features and integrations
4. Security and transaction handling
Secure mechanisms were implemented:
• authentication and authorization
• payment processing (deposits/withdrawals)
• protection of sensitive user data
5. Thoughtful UI/UX
The interface is focused on:
• intuitive navigation
• clear display of odds and bets
• responsiveness and mobile-first approach
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225 USD Agent of Beauty
Website Development
A turnkey website development service for client from Germany.
A ready-made product from idea to launch and support.
… Main stages:
1.Discovery & Strategy
2. Information Architecture & UX Design
3. UI & Visual Design
4. Frontend Development
5. Backend Development
6. Quality Assurance & Testing
7. Deployment & Launch
8. Post-Launch Support & Maintenance
Result for the client:
- Ready-made website with a unique design.
- Admin panel for content management.
- Full adaptability and SEO-base.
- Integrations with business processes (CRM, payments, analytics).
- Support after launch.
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225 USD Brands Stars
Website Development
A turnkey website development service.
A ready-made product from idea to launch and support.
… Main stages:
1.Discovery & Strategy
2. Information Architecture & UX Design
3. UI & Visual Design
4. Frontend Development
5. Backend Development
6. Quality Assurance & Testing
7. Deployment & Launch
8. Post-Launch Support & Maintenance
Result for the client:
- Ready-made website with a unique design.
- Admin panel for content management.
- Full adaptability and SEO-base.
- Integrations with business processes (CRM, payments, analytics).
- Support after launch.
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E-suvenir
Web Programming
EuroSouvenir is a Ukrainian company established in 1994 that specializes in the production and distribution of promotional and souvenir products branded with custom logos. The company serves corporate clients, helping them boost brand visibility through customized merchandise.
EuroSouvenir offers a wide variety of customizable items, including:
- Office supplies – pens, notebooks, organizers
… - Drinkware – mugs, thermoses
- Apparel and textiles – T-shirts, caps
- Electronic accessories – USB flash drives, power banks
- Seasonal gifts – umbrellas, beach gear
- Calendars and planners – wall and desk calendars, branded diaries
Each product can be branded with a logo or corporate design for marketing and promotional purposes.
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EuroSouvenir
Web Programming
EuroSouvenir is a Ukrainian company established in 1994 that specializes in the production and distribution of promotional and souvenir products branded with custom logos. The company serves corporate clients, helping them boost brand visibility through customized merchandise.
Main Product Categories
EuroSouvenir offers a wide variety of customizable items, including:
… - Office supplies – pens, notebooks, organizers
- Drinkware – mugs, thermoses
- Apparel and textiles – T-shirts, caps
- Electronic accessories – USB flash drives, power banks
- Seasonal gifts – umbrellas, beach gear
- Calendars and planners – wall and desk calendars, branded diaries
Each product can be branded with a logo or corporate design for marketing and promotional purposes.
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French Bedroom - UK-based luxury furniture boutique
Web Programming
French Bedroom is a UK-based luxury furniture boutique specializing in French-inspired bedroom furnishings. Founded in 2006 by Georgia Metcalfe, the company offers a curated selection of elegant and timeless pieces designed to transform bedrooms into serene sanctuaries.
French Bedroom's collections encompass a wide range of products, including:
- Beds & Mattresses: Featuring French beds, upholstered beds, rattan beds, and luxury mattresses.
… - Bedding & Linens: Offering premium bed linen, duvets, pillows, blankets, bedspreads, and luxury cushions.
- Furniture: Including bedside tables, console tables, dressing tables, chests, drawers, cabinets, armoires, wardrobes, seating options like chairs, armchairs, sofas, stools, and benches.
- Lighting: Comprising ceiling lights, wall lights, chandeliers, and table lamps.
- Décor & Accessories: Such as mirrors, rugs, French wall art, fragrances, candles, and various finishing touches.
The boutique also offers curated collections like "Amour," "Love Story," "Palais Royal," "Palais de Versailles," "Gustavian," "Chateauneuf," "Avenue Blanc," and "Avenue Montaigne," each reflecting distinct French design aesthetics.
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Yakaboo.ua - Ukraine's largest online bookstore
Web Programming
Yakaboo.ua is Ukraine's largest online bookstore and national book platform, offering over 200,000 books in 71 languages, including Ukrainian, English, and other European languages. The platform provides a wide range of formats, such as print, e-books, and audiobooks, catering to diverse reading preferences.
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ARVI SA is a premier Swiss-based merchant
Web Programming
ARVI SA is a premier Swiss-based merchant specializing in fine and rare wines, serving both private collectors and the hospitality industry worldwide. Established in 2004 and headquartered in Melano, Ticino, ARVI has become one of the largest stockholders and distributors of high-quality wines and spirits globally.
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G.A. Precision is a renowned American firearms manufacturer
Web Programming
G.A. Precision is a renowned American firearms manufacturer specializing in custom precision rifles and tactical equipment. Established in 1999 by George Gardner, the company is headquartered in North Kansas City, Missouri.
G.A. Precision specializes in crafting high-quality, professional-grade rifles that are both precise and affordable. The company uses top-notch, field-tested, durable parts and accessories to ensure the reliability and performance of their products.
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LIGA.net
Web Programming
LIGA.net is a prominent Ukrainian digital news platform that delivers comprehensive coverage of national and international events. Established in 1997, it has become one of Ukraine's most visited online news outlets, known for its commitment to independent journalism and in-depth reporting.
LIGA.net offers a wide range of content across various sections:
- News: Breaking news and updates on Ukrainian and global events.
… - Business: Insights into the Ukrainian economy, market trends, and corporate developments.
- Finance: Information on financial markets, banking, and investment opportunities.
- Technology: Coverage of technological advancements, startups, and IT industry news.
- Life: Human interest stories, lifestyle articles, and cultural pieces.
- Opinions: Editorials, expert analyses, and opinion pieces on current affairs.
- Special Projects: In-depth investigations and thematic series on significant topics.
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Pool-Profi24.de
Web Programming
Pool-Profi24.de is a German-based company specializing in the sale and installation of swimming pools and related equipment. Established in 2006, it operates both as an online retailer and a professional pool construction service provider for private and public clients.
Products and Services
Pool-Profi24 offers a comprehensive range of products and services, including:
… - Swimming Pools: Above-ground pools, steel wall pools, and styrofoam pools.
- Filtration and Pumps: Sand filters, circulation pumps, UV modules, and accessories.
- Heating Solutions: Electric heaters, solar heating systems, heat pumps, and heat exchangers.
- Water Treatment: Algae prevention, pH regulation, disinfectants (chlorine, bromine, oxygen), and water testers.
- Pool Accessories: Covers, ladders, lighting, cleaning equipment, and pool robots.
- Sauna and Whirlpool Equipment: Sauna stoves, fragrances, and whirlpool accessories
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Ally Fashion - Australian women's fast fashion retailer
Web Programming
Ally Fashion is an Australian women's fast fashion retailer, established in 2001, offering contemporary ready-to-wear clothing and accessories. The brand operates over 150 stores across Australia and maintains a global online presence, delivering to more than 70 countries worldwide.
Reviews and compliments on completed projects 3
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Real expert -
Craft master -
Quick answers -
First-class quality -
Nice communication -
High responsibility -
Great price -
Lightning fast
12 May
18 USD
I am looking for a Python mentor for an amateur project.
Quality
Professionalism
Cost
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Sergiy is an excellent specialist with extensive experience in the IT field. He thoroughly analyzed the project and provided his recommendations, assisting with the implementation. He supported at every step.
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14 August 2025
23 USD
Opening client card on mobile version
Quality
Professionalism
Cost
Contactability
Deadlines
everything was done correctly as in the technical assignment
Maksim B.
| Personal | Response review
9 August 2025
95 USD
Refactoring of React messenger application (component isolation)
Quality
Professionalism
Cost
Contactability
Deadlines
I did everything as planned, I recommend
figured out the complex project
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