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Hi, I’m Oleh Yurchenko, a Senior Software Engineer specializing in backend development, API integrations, and cloud-native applications, with a strong focus on blockchain solutions including smart contracts, DApps, and DeFi protocol integrations. Over 9 years, I’ve delivered enterprise-grade fintech, e-commerce, and SaaS blockchain applications and led teams to adopt secure, scalable architectures. I design secure blockchain infrastructures on Ethereum, Polygon, and other EVM networks, write Solidity and Web3.js/Ethers.js, and deploy to AWS with CI/CD automation. I enjoy turning complex requirements into robust platforms, optimizing gas costs, and mentoring engineers on best practices and security.…Hi, I’m Oleh Yurchenko, a Senior Software Engineer specializing in backend development, API integrations, and cloud-native applications, with a strong focus on blockchain solutions including smart contracts, DApps, and DeFi protocol integrations. Over 9 years, I’ve delivered enterprise-grade fintech, e-commerce, and SaaS blockchain applications and led teams to adopt secure, scalable architectures. I design secure blockchain infrastructures on Ethereum, Polygon, and other EVM networks, write Solidity and Web3.js/Ethers.js, and deploy to AWS with CI/CD automation. I enjoy turning complex requirements into robust platforms, optimizing gas costs, and mentoring engineers on best practices and security.

Oleh Yurchenko

Web Developer, Programmer, Developer, +5

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Hi, I’m Oleh Yurchenko, a Senior Software Engineer specializing in backend development, API integrations, and cloud-native applications, with a strong focus on blockchain solutions including smart contracts, DApps, and DeFi protocol integrations. Over 9 years, I’ve delivered enterprise-grade fintech, e-commerce, and SaaS blockchain applications and led teams to adopt secure, scalable architectures. I design secure blockchain infrastructures on Ethereum, Polygon, and other EVM networks, write Solidity and Web3.js/Ethers.js, and deploy to AWS with CI/CD automation. I enjoy turning complex requirements into robust platforms, optimizing gas costs, and mentoring engineers on best practices and security.…Hi, I’m Oleh Yurchenko, a Senior Software Engineer specializing in backend development, API integrations, and cloud-native applications, with a strong focus on blockchain solutions including smart contracts, DApps, and DeFi protocol integrations. Over 9 years, I’ve delivered enterprise-grade fintech, e-commerce, and SaaS blockchain applications and led teams to adopt secure, scalable architectures. I design secure blockchain infrastructures on Ethereum, Polygon, and other EVM networks, write Solidity and Web3.js/Ethers.js, and deploy to AWS with CI/CD automation. I enjoy turning complex requirements into robust platforms, optimizing gas costs, and mentoring engineers on best practices and security.

Available to hire

Hi, I’m Oleh Yurchenko, a Senior Software Engineer specializing in backend development, API integrations, and cloud-native applications, with a strong focus on blockchain solutions including smart contracts, DApps, and DeFi protocol integrations. Over 9 years, I’ve delivered enterprise-grade fintech, e-commerce, and SaaS blockchain applications and led teams to adopt secure, scalable architectures.

I design secure blockchain infrastructures on Ethereum, Polygon, and other EVM networks, write Solidity and Web3.js/Ethers.js, and deploy to AWS with CI/CD automation. I enjoy turning complex requirements into robust platforms, optimizing gas costs, and mentoring engineers on best practices and security.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

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Expert

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Expert

Expert

Expert

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Expert

Expert

Expert

Expert

Expert

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Expert

Intermediate

Language

English

Fluent

Polish

Fluent

Work Experience

Senior Software Engineer at TechWave

March 1, 2019 - Present

Led the development of a high-traffic React-based e-commerce platform with a Node.js back-end, leveraging microservices architecture and integrating Stripe/PayPal for secure payment processing, managing 500k+ monthly users. Architected a modular, maintainable front-end using React, Redux, and React Hooks, improving performance and simplifying state management for complex interactions. Developed custom React Hooks for optimized form validation, API requests, and side-effects management, improving component reusability. Designed scalable schemas and optimized queries using PostgreSQL and MySQL; integrated Redis for caching, MongoDB for semi-structured data, and Elasticsearch for advanced product search and filtering, reducing database response times by 35%. Integrated UI libraries like Material-UI and Ant Design, ensuring responsive design and polished user interfaces across devices. Leveraged React Query for efficient client-side data fetching and caching, enabling real-time UI updates,

Software Engineer at FinTech Innovations

February 1, 2019 - August 13, 2025

Developed and maintained Node.js back-end systems for real-time financial transaction processing, ensuring high availability and security for sensitive financial data. Designed and optimized GraphQL APIs to improve data retrieval efficiency and reduce over-fetching for React front-end applications. Integrated third-party services like Stripe and PayPal for secure payment workflows, ensuring PCI-DSS compliance with encrypted transactions. Improved back-end scalability by utilizing AWS, Docker, and NestJS for cloud-based deployments and containerization. Engineered high-performance data layers using SQL Server and Redis, optimizing query performance and session handling across financial microservices. Integrated React Query to manage GraphQL and REST data flows in React dashboards, enabling features like optimistic updates and stale-while-revalidate caching. Utilized Kafka for real-time data stream processing, optimizing financial data flow between systems. Optimized database queries wit

Software Engineer at ByteTech

September 1, 2016 - August 13, 2025

Assisted in developing React components for e-commerce platforms, handling product pages, shopping carts, and checkout flows, improving user conversion by 15%. Integrated Stripe and PayPal for secure payment transactions, ensuring smooth and reliable checkout experiences. Gained hands-on experience with MySQL and MongoDB for back-end database optimization, improving query execution times by 25%. Developed Node.js back-end services to handle RESTful API interactions focusing on product data, user management, and transactions. Optimized React components using React.memo and PureComponent to reduce unnecessary re-renders and improve platform performance. Developed and integrated real-time order tracking systems using Socket.IO and WebSockets, allowing users to track purchases in real-time. Assisted in migration of legacy code to React, refactoring components for better scalability and performance. Wrote unit tests using Jest and Enzyme to ensure stability and high-quality code before depl

Senior Software Engineer at TechWave

March 1, 2019 - Present

Led development of a high-traffic React-based e-commerce platform with Node.js back-end, integrating Stripe and PayPal for secure payment processing with 500k+ monthly users. Architected modular front-end using React, Redux, React Hooks. Developed custom React Hooks to optimize forms and API requests. Designed scalable schemas and optimized queries with PostgreSQL and MySQL, integrated Redis caching, MongoDB for semi-structured data, and Elasticsearch for advanced search capabilities, improving database response times by 35%. Incorporated Material-UI and Ant Design for responsive UI. Used React Query for client-side data fetching and caching, enabling real-time UI updates. Implemented real-time features with WebSockets and Socket.IO. Enhanced back-end maintainability with NestJS, event-driven architecture with Kafka, and real-time monitoring with ELK stack and Grafana. Improved back-end performance by refactoring GraphQL resolvers and Redis caching, reducing data fetch time by 30%. Led

Software Engineer at FinTech Innovations

April 1, 2019 - September 3, 2025

Developed and maintained Node.js back-end systems for real-time financial transaction processing ensuring high availability and security. Designed GraphQL APIs to optimize data retrieval for React front-end. Integrated Stripe and PayPal for PCI-DSS compliant payment workflows. Improved scalability using AWS, Docker, and NestJS for cloud deployments. Optimized high-performance data layers using SQL Server and Redis. Managed React Query for GraphQL and RESTful data flows enabling optimistic updates in transaction monitoring dashboards. Utilized Kafka for real-time data streaming, improved database query performance by 25% during peak load. Collaborated cross-functionally maintaining smooth data flow. Ensured code quality through Jest and Enzyme unit testing.

Software Engineer at ByteTech

September 1, 2016 - September 3, 2025

Supported development of React components for e-commerce platforms, improving user conversion by 15%. Integrated Stripe and PayPal for secure payments. Worked with MySQL and MongoDB to optimize back-end query execution by 25%. Developed Node.js RESTful APIs for product data, user management, and transactions. Optimized React components with React.memo and PureComponent to reduce re-renders and boost performance. Developed real-time order tracking using Socket.IO and WebSockets. Assisted migration of legacy code to React for scalability. Maintained code stability through Jest and Enzyme testing.

Senior Blockchain Engineer – Smart Contract & DApp Development Lead at TechWave

March 1, 2019 - Present

Designed and deployed Solidity contracts for token issuance (ERC-20, ERC-721) and NFT marketplace features; led the development of a DeFi staking and liquidity pool platform with Chainlink price feeds; built cryptocurrency payment gateways supporting Ethereum, USDC, BTC, and other tokens using Web3.js and Ethers.js; integrated MetaMask and WalletConnect into React and Vue DApps; optimized gas usage through storage refactoring and batch transactions; developed off-chain services for data indexing, event monitoring, and transaction queue processing; deployed infrastructure to AWS with Docker, Kubernetes, and CI/CD; conducted smart contract security audits; built admin dashboards for token management and contract interaction; mentored engineers on blockchain architecture and DeFi protocol integration.

Blockchain & API Integrations Engineer at FinTech Innovations

February 1, 2019 - September 12, 2025

Developed Node.js APIs for integrating blockchain payment processing into fintech applications; built secure crypto wallet services with multi-signature transaction support; implemented ERC-20 tokens for loyalty programs; created real-time blockchain event processing with Web3.js; integrated fiat-to-crypto gateways via Coinbase Commerce and BitPay; designed blockchain-based KYC/AML data verification workflows; built user-facing dashboards with blockchain analytics; optimized API response times with caching and event-driven patterns; ensured regulatory compliance for blockchain payments; wrote unit and integration tests to ensure reliability and security.

Software Engineer – Blockchain Prototype Developer at ByteTech

April 1, 2016 - September 12, 2025

Built proof-of-concept DApps for supply chain tracking using Ethereum smart contracts; integrated blockchain data with frontend dashboards via GraphQL APIs; developed Solidity contracts for ownership verification of digital assets; created custom Web3.js scripts for blockchain interactions and automation; implemented secure token storage and transaction signing; built event listeners to trigger notifications for blockchain transactions; deployed smart contracts to Ethereum testnets for QA validation; contributed to NFT metadata management systems for early marketplace prototypes; documented blockchain integration guidelines for internal teams.

Senior Blockchain Engineer – Smart Contract & DApp Development Lead at TechWave

March 1, 2019 - Present

Designed and deployed smart contracts in Solidity for token issuance (ERC-20, ERC-721) and NFT marketplace functionalities. Led the development of a DeFi staking and liquidity pool platform, integrating Chainlink oracles for real-time price feeds. Built cryptocurrency payment gateways supporting Ethereum, USDC, BTC, and other tokens using Web3.js and Ethers.js. Integrated MetaMask and WalletConnect authentication into React and Vue DApps. Optimized smart contract gas usage by refactoring storage patterns and implementing batch transactions. Developed off-chain services in Node.js for blockchain data indexing, event monitoring, and transaction queue processing. Deployed blockchain infrastructure to AWS with Docker, Kubernetes, and CI/CD pipelines for rapid updates. Conducted smart contract security audits to identify vulnerabilities before mainnet deployment. Built admin dashboards for token management, transaction monitoring, and contract interaction. Mentored engineers on blockchain a

Blockchain & API Integrations Engineer at FinTech Innovations

February 28, 2019 - September 12, 2025

Developed Node.js APIs for integrating blockchain payment processing into fintech applications. Built secure crypto wallet services with multi-signature transaction support. Implemented ERC-20 smart contracts for tokenized loyalty programs. Created transaction monitoring services with Web3.js to process blockchain events in real time. Integrated fiat-to-crypto payment gateways using Coinbase Commerce and BitPay APIs. Designed blockchain-based KYC/AML data verification workflows. Created user-facing dashboards displaying blockchain analytics and transaction histories. Optimized blockchain API response times using caching and event-driven architectures. Ensured compliance with financial regulations for blockchain payment handling. Wrote unit and integration tests for blockchain services to ensure reliability and security.

Software Engineer – Blockchain Prototype Developer at ByteTech

April 30, 2016 - September 12, 2025

Built proof-of-concept DApps for supply chain tracking using Ethereum smart contracts. Integrated blockchain data with frontend dashboards via GraphQL APIs. Developed Solidity contracts for ownership verification of digital assets. Created custom Web3.js scripts for blockchain interactions and automation. Implemented secure token storage and transaction signing. Built event listeners to trigger notifications for blockchain transactions. Collaborated with business teams to design blockchain use cases for B2B clients. Deployed smart contracts to Ethereum testnets for QA validation. Worked on NFT metadata management systems for early marketplace prototypes. Documented blockchain integration guidelines for internal teams.