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Andrii Saiak

@andriisaiak

Senior Backend & Blockchain Engineer (16+ yrs). Node.js/TypeScript, Solidity, stablecoin payments and multi-chain infrastructure.

Poland

Message

What I'm looking for

I’m looking for a Senior / Lead Backend or Blockchain Architect role (full-time remote or long-term contract) in a product company focused on fintech, payments, stablecoins, Web3 or AI. Strongest in Node.js/TypeScript microservices, multi-chain integrations, custody and Solidity.

At Sokin, I architect and build blockchain infrastructure for stablecoin payments, including transaction processing, wallet management, and secure key handling. I also develop multi-chain services for transaction broadcasting, balance tracking, and event indexing.

At Kuna, I architected Node.js and TypeScript microservices for a crypto payment platform, designing integrations for EVM and non-EVM networks. I also led technical direction and owned production monitoring for payment services.

Earlier, I built Solidity contracts for an NFT marketplace at Inoxoft and trading automation tools at Intelligent Community (Marcoin, Starbot), where I led a team of up to five engineers. I’m looking for a Senior or Lead Backend or Blockchain Architect role in a product company focused on fintech, payments, Web3, or AI.

Experience

Work history, roles, and key accomplishments

Current

Senior Backend Engineer / Blockchain Engineer

Current

Sokin

Dec 2025 - Present (11 months)

Architect and build blockchain infrastructure for stablecoin payments, including transaction processing, wallet management, and secure key handling. Develop microservices for blockchain integrations and design custody solutions.

Blockchain Stablecoins Microservices Transaction Processing Wallet Management Key Management Event Indexing Multi Chain Architecture

Senior Backend Engineer / Blockchain Architect

Kuna

Jan 2025 - Nov 2025 (10 months)

Architected and built Node.js/TypeScript microservices for a crypto payment platform. Designed API and blockchain integration layer for EVM and non-EVM networks, and led technical direction.

NodeJS TypeScript Microservices Blockchain API Design EVM Non EVM Chains Architecture Code Review Monitoring

Senior Backend (Blockchain) Engineer

Lacero Platform / Guardian Network

Jul 2023 - Dec 2024 (1 year 5 months)

Designed and built NestJS microservices, containerised with Docker and deployed to Kubernetes on IBM Cloud. Defined scalable, fault-tolerant backend architecture and provided technical guidance.

NestJS Microservices Docker Kubernetes IBM Cloud Architecture Code Review

Senior Backend (Blockchain) Engineer

RVA Fintech

Dec 2022 - Jul 2023 (7 months)

Built tools automating DEX interaction, including token swaps, price monitoring, and on-chain trade execution. Integrated Uniswap protocol at smart-contract level and improved performance via caching and query optimisation.

Blockchain Dex Uniswap Smart Contracts NestJS PostgreSQL Redis Performance Optimization

Blockchain Software Engineer / Senior Full Stack Developer

Ambisafe

Feb 2022 - Dec 2022 (10 months)

Performed smart-contract security audits for external clients and led modernisation of a legacy product, rewriting the Python backend in Node.js and rebuilding the frontend as a React/Redux SPA.

Smart Contracts Security Audits NodeJS NestJS PostgreSQL Redis React Redux API Integration

Blockchain Software Engineer

Inoxoft

Jun 2021 - Feb 2022 (8 months)

Developed Solidity smart contracts (ERC-721/ERC-1155) for an NFT marketplace, optimised for gas, and wrote Hardhat test suites. Worked with teams on Web3 integration.

Solidity Smart Contracts ERC721 ERC 1155 NFT Hardhat OpenZeppelin Web3

Tech Lead / Senior Full Stack Developer

Intelligent Community (Marcoin, Starbot)

Apr 2019 - Jun 2021 (2 years 2 months)

Led a team of up to 5 engineers building trading automation tools for crypto exchanges, defining architecture and owning the full lifecycle. Integrated Binance, Bitfinex, and Kraken APIs.

Team Leadership Architecture Trading Automation Binance Bitfinex Kraken Analytics Full Stack

Team Lead / Senior Full Stack Developer

MultiMiner

Jan 2017 - Jan 2019 (2 years)

Led the backend team across several internal products, defining architecture and coding standards for PHP services. Designed REST APIs and optimised database schemas.

Team Leadership PHP Laravel Zend REST APIs MySQL PostgreSQL Code Review

Full Stack Developer

GlobalAmuse Ltd. / In Game Studio

Jan 2013 - Jan 2017 (4 years)

Built backend services and APIs for mobile and social games, including authentication, real-time multiplayer, and in-app purchases. Owned server infrastructure end to end.

Backend APIs Mobile Games Authentication Real time Dashboards In App Purchases CI CD Monitoring