Senior Crypto Developer

📍 Warsaw, Poland | Hybrid | B2B Contract | English-speaking environment🌐 The OpportunityBuild 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 DoDesign, build and maintain enterprise-grade crypto and blockchain productsDevelop scalable distributed systems: APIs, orchestration layers and third-party integrationsBuild and enhance backend services in Java, collaborating with frontend teams on AngularOwn delivery end-to-end, from architecture and design through deployment and production supportDrive monitoring, alerting and high availability for mission-critical servicesImplement CI/CD pipelines, testing frameworks and secure engineering standards✅ What You'll Bring12+ 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 APIsDeep knowledge of blockchain technologies: public and permissioned chains, DeFi, distributed ledgers (Bitcoin, Ethereum, Hyperledger)Hands-on Solidity, EVM and Assembly experienceSolid grasp of security protocols and private key custodyFull Secure SDLC experience: version control, CI/CD, unit and performance testing⭐ Strongly PreferredFull-stack experience: Java backend + Angular frontendPayments, fintech or financial services domain knowledge, including compliance and payment processing flows💡 Why JoinWork on payments infrastructure used worldwide every day, where milliseconds matterBuild blockchain products inside a global financial leader, a rare combination on any CVCollaborate with senior international engineering teams in a hybrid Warsaw setup👉 Apply now. Shortlisted candidates will hear from our team within 48 hours.