Crypto Developer

📍 Warsaw, Poland | Hybrid | B2B Contract | English-speaking environment 🌐 The Opportunity Build blockchain and crypto products for a global payments technology leader whose platforms process real-time transactions for millions of businesses and consumers worldwide. This role suits a senior engineer who wants to work at genuine global scale, where security, resilience and performance are non-negotiable. 🛠 What You'll Do Design, build and maintain enterprise-grade crypto and blockchain products Develop scalable distributed systems : APIs, orchestration layers and third-party integrations Build and enhance backend services in Java , collaborating with frontend teams on Angular Own delivery end-to-end, from architecture and design through deployment and production support Drive monitoring, alerting and high availability for mission-critical services Implement CI/CD pipelines , testing frameworks and secure engineering standards ✅ What You'll Bring 12+ years' experience with a Bachelor's degree, or 8+ years with an advanced degree (Master's, MBA, etc.) Strong background building high-performance distributed systems and APIs Deep knowledge of blockchain technologies : public and permissioned chains, DeFi , distributed ledgers ( Bitcoin, Ethereum, Hyperledger ) Hands-on Solidity , EVM and Assembly experience Solid grasp of security protocols and private key custody Full Secure SDLC experience: version control, CI/CD , unit and performance testing ⭐ Strongly Preferred Full-stack expe