Bohdan K.

👋 𝐇𝐢, 𝐈’𝐦 𝐁𝐨𝐡𝐝𝐚𝐧, 𝐚 𝐒𝐞𝐧𝐢𝐨𝐫 𝐅𝐮𝐥𝐥 𝐒𝐭𝐚𝐜𝐤 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐞𝐫 𝐰𝐢𝐭𝐡 𝟕+ 𝐲𝐞𝐚𝐫𝐬 𝐨𝐟 𝐞𝐱𝐩𝐞𝐫𝐢𝐞𝐧𝐜𝐞. I build production web applications for FinTech, payments, SaaS, and Web3 products, working across frontend, backend, APIs, databases, integrations, and cloud infrastructure. My core stack is React, Next.js, Node.js, NestJS, Express, TypeScript, PostgreSQL, MongoDB, and AWS. I can take ownership of the full product flow: from frontend interfaces and dashboards to backend architecture, payment logic, integrations, and deployment. My Web3 experience includes wallets, crypto transactions, blockchain integrations, smart contracts, and off-chain infrastructure. I also use AI-assisted development and Spec-Driven Development to speed up implementation while keeping the codebase reliable and maintainable. • 7+ years in Full Stack and backend development • Backend infrastructure for a FinTech platform that raised $6.8M in seed funding • 15+ Upwork projects with 100% Job Success • Production experience with payments, wallets, banking integrations, and high-volume transaction systems • Up to 3x faster feature delivery with AI-assisted development, reusable modules, and automation 📌 𝐈𝐍𝐃𝐔𝐒𝐓𝐑𝐈𝐄𝐒 FinTech • Payments • Crypto & Web3 • eCommerce • SaaS • B2B Platforms • Sport & Fitness • Healthcare • EdTech • Logistic • HoReCa • Social Media 📌 𝐒𝐄𝐑𝐕𝐈𝐂𝐄𝐒 • Full Stack web application development • React and Next.js frontend development • Node.js, NestJS, and Express backend development • MVP & Proof of Concept development using AI-assisted Spec-Driven Development for faster validation • REST and GraphQL APIs • PostgreSQL, MongoDB, and database architecture • Payment flows, subscriptions, refunds, reconciliation, and reporting • Stripe, ACH, Apple Pay, Google Pay, BNPL, and banking integrations • Wallet infrastructure, crypto transactions, blockchain integrations, and Web3 development • AI agents, agentic workflows, RAG systems, LLM-powered automation, and OpenAI / Claude integrations • Authentication, KYC, permissions, webhooks, queues, and background jobs • AWS, Docker, CI/CD, monitoring, logging, and deployment 📌 𝐒𝐄𝐋𝐄𝐂𝐓𝐄𝐃 𝐖𝐎𝐑𝐊 Trustyfy | FinTech & Web3 Worked on a Spanish crypto and fiat platform that raised $6.8M in seed funding. Built Node.js and NestJS services, multi-wallet functionality, crypto tax calculations, collaboration flows, banking integrations, and integrations with Moralis, WalletConnect, and Snapshot. Arrears | FinTech & Payments Worked across backend and frontend on a FinTech platform with Stripe, ACH, Apple Pay, Google Pay, BNPL, partial payments, reconciliation, and financial reporting. Integrated Salesforce, QuickBooks, and Xero and contributed to product interfaces as a Full Stack Developer. Oxygen | Web3 & Brokerage Worked on a Solana-based brokerage using Serum’s on-chain order book. Built API architecture, blockchain integrations, transaction flows, and frontend connectivity. 💡 𝐇𝐄𝐑𝐄'𝐒 𝐖𝐇𝐄𝐑𝐄 𝐈 𝐂𝐀𝐍 𝐇𝐄𝐋𝐏 I usually help clients who need to: • build a FinTech, payment, or Web3 product from MVP to production • make payment flows reliable enough for production • add new features, refactor, or stabilize an existing Node.js backend • integrate Stripe, banking providers, KYC, wallets, blockchain services, and accounting systems • resolve issues with webhooks, retries, duplicate transactions, reconciliation, or provider failures • strengthen authentication, permissions, transaction state management, and audit trails • scale backend systems without slowing development • work with one Senior Backend Developer who can also cover Full Stack development You get senior Full Stack Developer ownership across React, Next.js, Node.js, NestJS, APIs, databases, payments, Web3 integrations, and AWS. I can join an existing engineering team, take ownership of a specific part of the product, or handle the full development cycle. 🚀𝐋𝐄𝐓’𝐒 𝐓𝐀𝐋𝐊 Send me your requirements, product, or architecture. I'll review the scope, technical risks, and recommend the best approach. full stack developer web developer node.js backend developer node.js backend developer javascript developer react developer node.js developer nodejs developer nodejs backend developer node js developer node.js react node.js graphql node.js aws node.js backend react.js node.js backend node.js backend nodejs nodejs react node full stack developer react node blockchain developer blockchain nft developer solidity web3 blockchain developer web3 developers web3 developer web 3 developer web3 development web3 dev web3 website web3 dapp web3.js react web3 react full stack web developer full stack developer react full-stack developer ful stack developer fullstack developer senior fullstack developer full stack react js full stack react full stack react developer fullstack react full stack mern