Senior Blockchain & Fintech EngineerBusiness Development Manager (Madrid) - Quanta Tech Systems Europe
18 hours ago
Madrid
Blockchain & Finance Lead — UEX.US Platform 📍 Location: Madrid, Spain (Hybrid — 3 days onsite) 🏢 Company: Quanta Tech Systems Europe (US-backed, Quanta Tech Systems LLC) 💼 Employment: Full-time, permanent (Spanish contract) 💰 Salary: €70,000 – €95,000 + bonus + token allocation About Us Quanta Tech Systems Europe is building the core infrastructure behind UEX.US — a next-generation, U.S.-regulated digital asset exchange (Wyoming, est. 2025). Our platform combines: • Crypto trading, • Staking & yield products, • Crypto-backed lending, • On-chain settlement, • Wallet & custody infrastructure, • Exchange core (matching, ledger, reconciliation), • Build Go services interacting with:, • EVM chains (Ethereum, Polygon, Arbitrum, Base), • Non-EVM (Bitcoin, Solana, XRP, Cardano), • Own wallet infrastructure:, • HD wallets (BIP-32/39/44), • HSM / MPC integrations, • Hot / warm / cold architecture, • Develop:, • Indexers & reorg-safe pipelines, • Gas optimization tools, • Integrate custody providers:, • Fireblocks, Copper, BitGo, • Review smart contracts & define listing security standards Finance & Exchange Systems, • Work on:, • Order book & matching engine, • Ledger & settlement systems, • Ensure:, • Double-entry accounting, • Idempotency, • Cross-chain reconciliation, • Build fiat integrations:, • PayPal, Zelle, Apple Pay, cards, • Implement:, • Crypto-backed loans, • Staking rewards, • APY-based savings Leadership & Ownership, • Act as domain tech lead (blockchain + finance), • Define:, • Engineering standards, • Observability & incident response, • Mentor engineers & support hiring, • Drive architecture via RFCsMust-Have, • Go (Golang) — 4+ years in production systems, • Blockchain/Web3 — 2+ years (Ethereum or similar), • Strong understanding of:, • Transactions, gas, nonce, reorgs, • Cryptography (ECDSA, keccak), • Fintech experience:, • Exchanges / payments / ledger systems, • Distributed systems:, • Kafka, PostgreSQL, Redis, • Cloud & Infra:, • AWS, Docker, Kubernetes, CI/CD, • Security mindset:, • Key management, attack vectors, front-running, • 🤖 Claude Code (required):, • Daily usage, • AI-assisted workflows, • 🇬🇧 English — professional level Nice to Have, • Solidity / Rust, • Experience in:, • Crypto exchange / neobank, • Regulatory knowledge:, • MiCA / FinCEN / SEC, • MPC / HSM (CloudHSM, Vault, etc.), • Open-source contributions (geth, Bitcoin Core, etc.) Chains: Ethereum, Polygon, Bitcoin, Solana, XRP, Cardano Data: PostgreSQL, Redis, Kafka, ClickHouse Infra: AWS, Kubernetes (EKS), Terraform Security: Vault, AWS KMS, Fireblocks, Chainalysis Observability: Prometheus, Grafana, OpenTelemetry AI: Claude Code, Claude Opus 4.7 Compensation & Benefits • 💰 €70k – €95k salary, • 📈 Bonus up to 15%, • 🪙 Token allocation (vesting), • 💻 MacBook / Linux workstation + €2,000 setup, • 📚 €2,500 learning budget (Devcon, EthCC, Money20/20), • 🏥 Private health insurance (Sanitas / Adeslas), • 🌴 25 vacation days + holidays, • ✈️ Travel (NYC, London, Paris, Brussels), • 🌍 Relocation support + visaHiring Process, • Intro call (30 min), • Technical interview (Go + blockchain), • Take-home (paid): ERC-20 indexer, • System design (custody + settlement), • VP Engineering interview, • Offer (2–3 weeks total)