Bohdan — Blockchain & Web3 freelancer in Kyiv

I help FinTech and Web3 teams build APIs, payment flows, and blockchain infrastructure. 7+ years of experience. 15 projects on Upwork. Built products for startups that raised up to $6.8M in seed funding. Senior Backend Developer specializing in blockchain integrations and FinTech infrastructure. 𝐏𝐫𝐨𝐣𝐞𝐜𝐭𝐬 𝐈'𝐦 𝐩𝐫𝐨𝐮𝐝 𝐨𝐟: Trustyfy - Spanish blockchain-first fintech platform for crypto & fiat asset management. Raised $6.8M in seed funding. Built backend infrastructure for multi-wallet management, crypto tax calculation, team collaboration, and crypto-friendly banking integration. Stack: NestJS, Moralis, WalletConnect, Web3React, Snapshot. Arrears - Debt collection platform with full payment infrastructure: Stripe, ACH, Apple\u002FGoogle Pay, Buy Now Pay Later, and partial payments. Integrated with Salesforce CRM, QuickBooks, and Xero. Built dashboards and data visualization with Recharts. Oxygen - DeFi prime brokerage service on Solana, powered by Serum's on-chain infrastructure. Responsible for frontend and API integration. 𝐓𝐞𝐜𝐡 𝐬𝐭𝐚𝐜𝐤: ⚡ Backend: Node.js, Express, NestJS, REST, GraphQL ⚡ Blockchain: Solidity, Ethers.js, Web3.js, Polygon, Ethereum, Solana ⚡ FinTech: Fireblocks, Coinbase API, Kraken, Gnosis Safe, Bridge.xyz, Rain.xyz, Moralis, Elliptic, Sumsub ⚡ Payments: Stripe, ACH, Apple Pay, Google Pay ⚡ Databases: MongoDB, PostgreSQL, Supabase, Firebase ⚡ Frontend: React, Next.js, TypeScript, Tailwind CSS ⚡ Infrastructure: AWS, Azure, Google Cloud, CI\u002FCD 𝐄𝐱𝐩𝐞𝐫𝐢𝐞𝐧𝐜𝐞: Blockchain & Web3 DeFi protocols, crypto wallets, smart contract integrations, DEX\u002FDApp development, with hands-on experience across Fireblocks, Coinbase API, Kraken, Gnosis Safe, and Moralis FinTech Infrastructure Payment systems (Stripe, ACH, Apple\u002FGoogle Pay), KYC\u002FKYB flows (Sumsub), AML compliance (Elliptic), crypto-fiat operations (Bridge.xyz, Rain.xyz) Backend Architecture Scalable REST and GraphQL APIs with Node.js, Express, NestJS, designed for high load, clean separation of concerns, and easy maintenance Databases & Infrastructure MongoDB, PostgreSQL, Supabase, Firebase, AWS, Azure, Google Cloud, CI\u002FCD pipelines Full Stack Next.js, React, TypeScript, when the project needs frontend coverage alongside backend expertise 𝐖𝐡𝐚𝐭 𝐰𝐨𝐫𝐤𝐢𝐧𝐠 𝐰𝐢𝐭𝐡 𝐦𝐞 𝐥𝐨𝐨𝐤𝐬 𝐥𝐢𝐤𝐞: ✓ Backend architecture designed for scale from day one ✓ Deep FinTech and blockchain integration experience ✓ Clean, well-structured code your team can build on long-term ✓ Proactive communication and transparent progress throughout the project The backend is where products either scale or break. Let's make sure yours scales. Message me and we’ll review your project together.