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Vitalii A.

@jonhw5

5,0
6

4,0

4,0

100%

Full Stack Developer | MERN

$35 USD / Stunde

・

Flagge von

Czech Republic (12:15 PM)

・

Joined on Oktober 13, 2025

・

1 Empfehlungen

$35 USD / Stunde

・

I'm a Senior Full Stack Developer with 8+ years of experience building high-quality web and mobile applications using React.js, Next.js, Vue, Nuxt.js, Node.js, Nest.js, PHP, Laravel, Wordpress, Python (Django, FastAPI), React Native, and Flutter. I specialize in creating scalable, secure, and high-performing solutions with clean architecture and intuitive UI. From RESTful APIs to cloud deployment, I deliver complete end-to-end products using AWS, Azure, and GCP. My expertise covers E-commerce, Fintech, and SaaS platforms, integrating modern tools like TypeScript, Tailwind CSS, and DevOps automation to ensure smooth, reliable performance. I take pride in clear communication, efficient collaboration, and delivering projects that exceed expectations. Let’s turn your idea into a world-class product 🚀

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Pünktlich

100 %

Im Budget

100 %

Annahmequote

39 %

Freelancer PHP Developers Czech Republic
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Portfolio

Portfolio

13821136
I designed the server side architecture for a Root App gaming platform, focusing on performance, stability, and scalability for real time gameplay. I planned the full backend structure including authentication, player profiles, matchmaking or lobby flow, game session management, and secure APIs for the client app. I also designed the data layer to store user progress, in game assets, leaderboards, and transaction history with a structure that supports fast reads and clean updates. On the infrastructure side, I prepared the deployment approach for production with environment separation, logging and monitoring, and a scalable setup that can handle traffic spikes during peak hours. I ensured the design includes security best practices such as token based authentication, rate limiting, input validation, and anti abuse protection, while keeping the system easy to maintain and extend as new game modes and features are added.

Root App Gaming Server Design

I designed the server side architecture for a Root App gaming platform, focusing on performance, stability, and scalability for real time gameplay. I planned the full backend structure including authentication, player profiles, matchmaking or lobby flow, game session management, and secure APIs for the client app. I also designed the data layer to store user progress, in game assets, leaderboards, and transaction history with a structure that supports fast reads and clean updates. On the infrastructure side, I prepared the deployment approach for production with environment separation, logging and monitoring, and a scalable setup that can handle traffic spikes during peak hours. I ensured the design includes security best practices such as token based authentication, rate limiting, input validation, and anti abuse protection, while keeping the system easy to maintain and extend as new game modes and features are added.

Root App Gaming Server Design

I designed the server side architecture for a Root App gaming platform, focusing on performance, stability, and scalability for real time gameplay. I planned the full backend structure including authentication, player profiles, matchmaking or lobby flow, game session management, and secure APIs for the client app. I also designed the data layer to store user progress, in game assets, leaderboards, and transaction history with a structure that supports fast reads and clean updates. On the infrastructure side, I prepared the deployment approach for production with environment separation, logging and monitoring, and a scalable setup that can handle traffic spikes during peak hours. I ensured the design includes security best practices such as token based authentication, rate limiting, input validation, and anti abuse protection, while keeping the system easy to maintain and extend as new game modes and features are added.

Root App Gaming Server Design

13821108
I resolved a Python package bug by reproducing the issue locally, reviewing the traceback and environment details, and isolating the root cause in the dependency and import flow. I then applied a clean fix by updating the problematic module logic and adjusting version constraints to prevent the error from recurring across different Python versions. After implementing the patch, I validated the solution with targeted tests, verified the package installs and runs correctly in a fresh virtual environment, and documented the fix steps so it is easy to maintain and release.

Resolve Python Package Bug

13821099
I built a WhatsApp and SMS based chatbot that helps businesses reply to customers instantly, capture leads, and automate common conversations without needing a human agent online 24/7. The bot can receive messages from WhatsApp and SMS, understand user inputs, and respond with the right flow such as FAQs, order or booking inquiries, pricing requests, support ticket creation, and contact collection. The system is designed for real business use, so it includes clean conversation flows, opt-out handling for SMS, and message logging so you can track what users asked and how the bot responded. It can also route complex questions to a human, and can connect to external tools like a CRM, Google Sheets, or a backend API for saving leads and triggering actions.

WhatsApp + SMS Based ChatBot

13734113
A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

13673071
The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

13673063
The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

13821136
I designed the server side architecture for a Root App gaming platform, focusing on performance, stability, and scalability for real time gameplay. I planned the full backend structure including authentication, player profiles, matchmaking or lobby flow, game session management, and secure APIs for the client app. I also designed the data layer to store user progress, in game assets, leaderboards, and transaction history with a structure that supports fast reads and clean updates. On the infrastructure side, I prepared the deployment approach for production with environment separation, logging and monitoring, and a scalable setup that can handle traffic spikes during peak hours. I ensured the design includes security best practices such as token based authentication, rate limiting, input validation, and anti abuse protection, while keeping the system easy to maintain and extend as new game modes and features are added.

Root App Gaming Server Design

I designed the server side architecture for a Root App gaming platform, focusing on performance, stability, and scalability for real time gameplay. I planned the full backend structure including authentication, player profiles, matchmaking or lobby flow, game session management, and secure APIs for the client app. I also designed the data layer to store user progress, in game assets, leaderboards, and transaction history with a structure that supports fast reads and clean updates. On the infrastructure side, I prepared the deployment approach for production with environment separation, logging and monitoring, and a scalable setup that can handle traffic spikes during peak hours. I ensured the design includes security best practices such as token based authentication, rate limiting, input validation, and anti abuse protection, while keeping the system easy to maintain and extend as new game modes and features are added.

Root App Gaming Server Design

I designed the server side architecture for a Root App gaming platform, focusing on performance, stability, and scalability for real time gameplay. I planned the full backend structure including authentication, player profiles, matchmaking or lobby flow, game session management, and secure APIs for the client app. I also designed the data layer to store user progress, in game assets, leaderboards, and transaction history with a structure that supports fast reads and clean updates. On the infrastructure side, I prepared the deployment approach for production with environment separation, logging and monitoring, and a scalable setup that can handle traffic spikes during peak hours. I ensured the design includes security best practices such as token based authentication, rate limiting, input validation, and anti abuse protection, while keeping the system easy to maintain and extend as new game modes and features are added.

Root App Gaming Server Design

13821108
I resolved a Python package bug by reproducing the issue locally, reviewing the traceback and environment details, and isolating the root cause in the dependency and import flow. I then applied a clean fix by updating the problematic module logic and adjusting version constraints to prevent the error from recurring across different Python versions. After implementing the patch, I validated the solution with targeted tests, verified the package installs and runs correctly in a fresh virtual environment, and documented the fix steps so it is easy to maintain and release.

Resolve Python Package Bug

13821099
I built a WhatsApp and SMS based chatbot that helps businesses reply to customers instantly, capture leads, and automate common conversations without needing a human agent online 24/7. The bot can receive messages from WhatsApp and SMS, understand user inputs, and respond with the right flow such as FAQs, order or booking inquiries, pricing requests, support ticket creation, and contact collection. The system is designed for real business use, so it includes clean conversation flows, opt-out handling for SMS, and message logging so you can track what users asked and how the bot responded. It can also route complex questions to a human, and can connect to external tools like a CRM, Google Sheets, or a backend API for saving leads and triggering actions.

WhatsApp + SMS Based ChatBot

13734113
A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

A modern inventory management app that simplifies stock tracking through real-time updates, automated calculations, and detailed transaction records. Engineered with performance-optimized workflows, cloud-ready infrastructure, and mobile-first design.

Smart Inventory Control App

13673071
The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

The website is the “Column” section of the Shionogi Healthcare Co., Ltd. “Berizym Enzyme” site, where they publish articles about nutritional topics like malnutrition, frailty, and digestive enzymes. It provides short, informative posts geared toward health-conscious readers.

Shionogi Healthcare

13673063
The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

The Thinky “Nanko” series is a compact mixing device designed for pharmacies to efficiently prepare ointments by automating the traditional hand-kneading process. It ensures uniform blending, saves time, and maintains cleanliness and consistency in pharmaceutical compounding.

Doctor Booking

5.0 · 6 Rezensionen
Bewertungen
L

Subscriber-Only Guitar Chord Viewer • £50 GBP

"Vitalii A, is a professional and highly communicative developer. He followed my instructions precisely and successfully set up the essential groundwork for this project. Throughout our collaboration, he was responsive, easy to reach, and handled project feedback with a great attitude. He is a reliable professional who takes direction well, and I appreciate his contribution to the early stages of this build." Thank you.

Paul G.

@LlewellynAve

•

Flagge von

Hengoed, United Kingdom

•

vor 13 Stunden

Teilen

Avatar des Nutzers

Professional Wix Website Redesign • $800 HKD

Outstanding freelancer. They understood the requirements quickly, proposed a clean approach, and executed with great attention to detail. Updates were consistent, timelines were respected, and any issues were fixed promptly. The final delivery was stable, well structured, and easy to maintain. Highly recommend for any serious project and I will gladly work with them again.

Felix L.

@xvideostoy

•

Flagge von

Shenzhen, China

•

vor 8 Tagen

Teilen

L

Discord Gaming Server Design • $390 USD

Great job. A++++++++++

Josh W.

@likethecure

•

Flagge von

Davidson, United States

•

vor 11 Tagen

Teilen

M

Resolve Python Package Bug • $50 AUD

excellent. Very good at what he does. highly recommend

Mark K.

@Markkyk

•

Flagge von

merrylands, Australia

•

vor 14 Tagen

Teilen

Avatar des Nutzers

"TV Mounting" Lead-Gen Landing Page on Google Page Speed 100% + SEO. • $230 USD

Vitalii is a reliable, highly skilled developer who delivered our landing page end-to-end. He achieved top Google PageSpeed results (green zone, including 100/100 Performance & Best Practices), with clean, optimized code. He also thinks like a marketer: structures sections for conversion and builds lead-gen naturally. Strong frontend + can set up backend/forms/integrations. Fast communication, quick updates, very responsible. Highly recommended.

Roman P.

@k0dzer0

•

Flagge von

Roseville, United States

•

vor 17 Tagen

Teilen

Erfahrung

Full Stack Developer

Feb., 2024 - Sept., 2025

•

1 Jahr, 7 Monate

Floy GmbH

Feb., 2024 - Sept., 2025

•

1 Jahr, 7 Monate

- Designed and developed ERP microservices using Python, FastAPI, and PostgreSQL for real-time business workflow and inventory tracking. - Built a scalable frontend with Next.js and React, integrating GraphQL APIs to deliver AI-powered predictive analytics dashboards. - Implemented AI-driven features using OpenAI APIs in Python for automated document summarization and financial anomaly detection.

Flagge von

Munich, Germany

Feb., 2024 - Sept., 2025

•

1 Jahr, 7 Monate

Full Stack Engineer

Juni, 2021 - Dez., 2023

•

2 Jahre, 6 Monate

Siesta Labs

Juni, 2021 - Dez., 2023

•

2 Jahre, 6 Monate

- Developed and maintained scalable web and mobile applications using React, Next.js, Node.js, NestJS, and React Native. - Designed and optimized RESTful APIs, improved frontend performance, and implemented reusable components. - Collaborated with cross-functional teams to deliver high-quality, user-centric solutions on time and within scope.

Flagge von

Prague, Czech Republic

Juni, 2021 - Dez., 2023

•

2 Jahre, 6 Monate

Full Stack Developer

Okt., 2017 - Mai, 2021

•

3 Jahre, 7 Monate

Fragaria

Okt., 2017 - Mai, 2021

•

3 Jahre, 7 Monate

- Built responsive web applications using React, Redux, Material-UI, and TypeScript, increasing user engagement by 30% through improved UX and performance. - Refactored monolithic backends into modular Python microservices using Django and FastAPI, enhancing scalability and maintainability of financial systems. - Implemented real-time UI updates with Django Channels and WebSockets, reducing frontend latency by 25% for transaction and notification features.

Flagge von

Prague, Czech Republic

Okt., 2017 - Mai, 2021

•

3 Jahre, 7 Monate

Bildung

Czech Technical University in Prague

2013 - 2017

•

4 Jahre

Bachelor

Flagge von

Czech Republic

2013 - 2017

•

4 Jahre

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