Valentin Kit
Создаю работающие решения
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Kyiv,
Ukraine
25 days 22 hours back
available for hire
age 25 years
on the service 8 years
Rating
Successful projects
Average rating
Language proficiency level
Українська: fluent
Русский: fluent
English: upper-intermediate
Skills and abilities
Programming
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Cryptocurrency & Blockchain
from 117 USD for project
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Databases & SQL
from 95 USD for project
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HTML & CSS
from 68 USD for project
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Java
from 95 USD for project
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Javascript and Typescript
from 95 USD for project
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Python
from 95 USD for project
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Web Programming
from 95 USD for project
Design & art
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Interface Design (UI/UX)
from 95 USD for project
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Logo Design
from 95 USD for project
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Mobile Apps Design
from 95 USD for project
Portfolio
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10 000 USD M&V Coin — a next-generation crypto platform
Cryptocurrency & Blockchain
M&V Coin is a multifunctional crypto product that combines a user-friendly mobile application, a powerful backend built on a microservices architecture, and deep integration with external services and cryptocurrency exchanges.
Frontend: mobile application
• Cross-platform app built with React Native, supporting both iOS and Android
… • Simple and secure authentication via phone number
• Intuitive interface for:
• crypto wallet management
• cross-chain transfers
• P2P trading
• token farming
• Integrated Telegram game synchronized with the app, allowing users to earn tokens, participate in farming, and increase their engagement within the ecosystem
Backend: Java + microservices
• Microservices-based architecture using Java and Spring Boot
• Integration with WhiteBit includes:
• deposits and withdrawals to exchange-generated addresses
• balance retrieval and display
• cross-chain transfers via the exchange API
• Custom-built P2P marketplace:
• trade logic
• user verification system
• transaction history and analytics
• Integration of a native token with tokenomics tailored for in-app usage
Security and reliability
• Authentication with phone verification and additional security checks
• Backend protection using JWT, rate limiting, and audit logging
• Secure storage of sensitive data with server-side encryption
• Monitoring and logging via Grafana and Prometheus
Admin panel
• Dashboard with key metrics
• Monitoring of P2P trades and user activity
• Manual moderation and blocking capabilities
• Flexible configuration of tokenomics, rates, and limits
Token and internal economy
• Native token designed for:
• incentivizing user activity
• gamification
• paying fees
• Reward system for user actions such as transfers, farming, and game participation
• Ability to withdraw earned tokens or use them within the platform
Key technologies
• React Native
• Java (Spring Boot)
• PostgreSQL
• Redis / RabbitMQ
• WebSocket (for real-time updates)
• WhiteBit API
• Telegram Bot API
• Docker + Kubernetes
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1000 USD Cross-Chain Bridge
Cryptocurrency & Blockchain
A cross-chain bridge was developed to enable the transfer of digital assets between multiple blockchain networks. The primary goal of the project is to provide a secure, decentralized, and максимально fast token transfer without intermediaries. The solution is implemented as a full-fledged DeFi infrastructure prototype with multi-network support and automated transaction routing via smart contracts and oracle mechanisms.
TECHNICAL IMPLEMENTATION:
• Asset transfers are supported across Ethereum, BNB Smart Chain, Polygon, Arbitrum, and Avalanche.
… • Cross-chain communication and message routing are handled using LayerZero, Wormhole, and Axelar protocols.
• An oracle system based on Chainlink is integrated to validate price feeds and transaction states.
• Smart contracts are written in Solidity; deployment and testing are performed using Hardhat with multichain configuration support.
• The ERC-20 standard is used for tokens, with implemented wrapped tokens and bridge contracts for locking and minting assets.
• A relay server built with Node.js (Express) handles event tracking, transaction status processing, and cross-chain synchronization.
• Monitoring is implemented with Prometheus and Grafana, while MongoDB is used for storing logs and transaction states.
• The client-side application is built with React, integrated via Wagmi and RainbowKit, and supports MetaMask and WalletConnect.
RESULT:
• A fully functional MVP enabling bidirectional token transfers across supported networks.
• Average transaction time during devnet testing is up to 30 seconds.
• A multisignature verification system and event logging are implemented to ensure operational transparency.
• The interface automatically detects the user’s network and handles errors in real time.
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6000 USD OMPrice — AI platform for price scanning and analysis
Web Programming
OMPrice is a mobile application designed for automatic price tag scanning and price analytics. Users upload photos, and the system processes them using AI, returning structured pricing data.
Frontend: mobile application
… Cross-platform app built with React Native (iOS + Android)
Authentication: Email/password, Google Sign-In, Apple Sign-In
Intuitive UI with animations (Reanimated) and blur effects
Two result display modes: grid and list
Bulk photo selection with deletion capability
Task system: create → upload photos → processing → result
Real-time polling of task processing status
Offline support with data caching (AsyncStorage)
Network status indicator
Localization: Ukrainian and English (i18next + device language detection)
Backend integration
REST API for managing tasks, users, and transactions
Smart caching: API → cache → fallback when offline
Image uploads via a custom queue-based uploader
Polling task statuses with automatic data refresh
Email verification via confirmation code
Monetization & billing
Internal balance (wallet) displayed in USD
Top-ups via Google Play In-App Purchases (consumable products)
Global purchase listener — handles payments across all screens, including incomplete transactions (app crash or closure)
Backend payment verification
Pricing tiers with per-photo cost and automatic tier switching
Transaction history with caching
Security
JWT-based authentication
Secure token storage using Keychain/Keystore
Email verification during registration
UX & design
Dark theme with gradient buttons and blur cards
Bottom-sheet modals for profile editing and task creation
Animated transitions and micro-interactions (Reanimated + Spring)
Skeleton loaders and toast notifications
In-App Review after the first successful result
FAQ screen and deleted tasks bin
In-App WebView for Terms and Privacy Policy
Core technologies
React Native + TypeScript
NativeWind (TailwindCSS)
React Native Reanimated
Zustand (state management)
AsyncStorage (caching)
react-native-iap (In-App Purchases)
react-native-keychain
react-native-in-app-review
i18next (localization)
react-native-bootsplash
react-native-google-signin
invertase/react-native-apple-authentication
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1000 USD Online Learning Platform
Web Programming
The brand design course platform is a custom-built educational system designed to organize the learning process, facilitate interaction with students, and scale an авторский курс. The platform combines educational content, a personalized user experience, and tools for tracking progress and results.
Technologies:
• Backend: Node.js
… The server-side is built with scalability and efficient user data handling in mind. The API manages authentication, content management (courses, modules, lessons), homework processing, and user interaction within the system.
• Database: MongoDB
A flexible data structure enables efficient handling of users, educational content, progress tracking, and assignments.
• Frontend: React
The interface is developed as a responsive web platform focused on usability. It includes intuitive navigation between modules and lessons, dynamic content loading, and a personalized user experience.
Features:
• Structured learning system (modules → lessons → progress).
• Personal user dashboard with progress tracking.
• Homework submission and review system.
• Feedback system between students and instructor.
• Personalized internal marketplace for materials and products.
• Role-based access system (student, instructor, admin).
Project Goal:
To create a scalable and user-friendly online learning platform that combines content, practice, and interaction, delivering an effective educational experience and a комфортный user journey.
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soloviy — an app about connection
Web Programming
soloviy is a mobile application designed to preserve and promote the linguistic richness of Ukraine. The platform brings together dialects, surzhyk, regional expressions, and idioms, allowing users to explore language diversity across different regions.
Technologies:
• Backend: Java + Spring Boot
… The backend is built as a REST API with authentication, data validation, and user-generated content handling. The architecture includes separate endpoints for managing words, categories, users, search, and interactions (likes).
• Database: MySQL
A relational database structure is used, with logical connections between words, regions, categories, and user activity. Indexing ensures fast search and filtering performance.
• Frontend: React Native
A cross-platform mobile application with a responsive interface. Features include client-side search, dark mode support, dynamic content loading, and full API integration.
Features:
• Adding new words with moderation.
• Browsing and filtering content by regions of Ukraine.
• User accounts and authentication system.
• Likes, popular words, and category-based search.
• Role-based access system (user, moderator, administrator).
Project Goal:
To create a digital space where the Ukrainian language in all its diversity becomes accessible, understandable, and alive through user interaction and modern technologies.
#springboot #mysql #restapi #reactnative #mobileapp #ukrainianlanguage #backenddevelopment #communityplatform
