Senior Blockchain & Fintech EngineerBusiness Development Manager (Madrid)
Quanta Tech Systems Europe · Madrid, Community of Madrid, Spain
- On site
- Full-time
- €82,500 / year
- Madrid, Community of Madrid, Spain
Job highlights
- Lead blockchain and fintech systems development.
- Build Go services for EVM and non-EVM chains.
- Own wallet and custody infrastructure.
- Develop exchange core and financial systems.
- Provide technical leadership and mentorship.
About the role
About Quanta Tech Systems Europe
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
- Tokenized real-world assets (gold, silver, equities)
Your Mission
You will be the technical anchor for blockchain and financial systems:- On-chain settlement
- Wallet & custody infrastructure
- Exchange core (matching, ledger, reconciliation)
- Fiat ↔ crypto rails
What You’ll Do
🔗 Blockchain Engineering- Build Go services interacting with EVM chains (Ethereum, Polygon, Arbitrum, Base) and 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
- 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
- Act as domain tech lead (blockchain + finance)
- Define: Engineering standards, Observability & incident response
- Mentor engineers & support hiring
- Drive architecture via RFCs
Must-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.)
- RWA (tokenized assets) experience
Tech Stack
- Languages: Go, TypeScript, Solidity, Rust
- 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 + visa
Hiring Process
- Intro call (30 min)
- Technical interview (Go + blockchain)
- Take-home (paid): ERC-20 indexer
- System design (custody + settlement)
- VP Engineering interview
Key skills/competency
- Go
- Blockchain
- Fintech
- EVM
- Wallets
- Custody
- Exchange
- Security
- Distributed Systems
- AWS
Skills & topics
- Blockchain Engineer
- Fintech Engineer
- Go Developer
- Ethereum Developer
- Solana Developer
- Crypto Exchange
- Digital Assets
- AWS
- Kubernetes
- Distributed Systems
How to get hired
- Tailor your resume: Highlight Go, blockchain, and fintech experience. Quantify achievements.
- Showcase technical skills: Emphasize experience with EVM/non-EVM chains and wallet infrastructure.
- Demonstrate leadership: Provide examples of technical leadership and system design.
- Prepare for interviews: Be ready for Go, blockchain, and system design discussions.
- Understand the business: Research UEX.US and Quanta Tech Systems Europe's mission.
Technical preparation
Master Go concurrency and error handling.,Deep dive into EVM and non-EVM transaction details.,Practice wallet architecture and HSM/MPC concepts.,Design secure settlement and ledger systems.
Behavioral questions
Describe a complex technical challenge you solved.,How do you ensure system security in finance?,Tell me about mentoring junior engineers.,How would you handle a critical system incident?
Frequently asked questions
- What is the work arrangement for the Senior Blockchain & Fintech Engineer role at Quanta Tech Systems Europe?
- The Senior Blockchain & Fintech Engineer role at Quanta Tech Systems Europe is a hybrid position, requiring 3 days onsite at their Madrid office.
- What are the key responsibilities of a Senior Blockchain & Fintech Engineer at Quanta Tech Systems Europe?
- Key responsibilities include building Go services for various blockchain chains, owning wallet and custody infrastructure, developing exchange core systems, and acting as a technical lead for blockchain and finance.
- What compensation can I expect as a Senior Blockchain & Fintech Engineer at Quanta Tech Systems Europe?
- The salary range for this role is €70,000 – €95,000 annually, plus a bonus of up to 15% and token allocation with vesting.
- What is the hiring process for the Senior Blockchain & Fintech Engineer position?
- The hiring process involves an intro call, a technical interview (Go + blockchain), a paid take-home assignment (ERC-20 indexer), a system design interview (custody + settlement), and a final interview with the VP of Engineering.
- What blockchain experience is required for the Senior Blockchain & Fintech Engineer role at Quanta Tech Systems Europe?
- A minimum of 2 years of experience with Blockchain/Web3, specifically with Ethereum or similar chains, is required. Experience with EVM and non-EVM chains is highly valued.
- Does Quanta Tech Systems Europe offer relocation support for this role?
- Yes, Quanta Tech Systems Europe offers relocation support and visa assistance for candidates hired for the Senior Blockchain & Fintech Engineer position.
- What programming languages are essential for the Senior Blockchain & Fintech Engineer role?
- Proficiency in Go (Golang) with over 4 years in production systems is a must-have. Experience with TypeScript, Solidity, or Rust is considered a plus.
- What kind of fintech experience is Quanta Tech Systems Europe looking for in a Senior Blockchain & Fintech Engineer?
- They are looking for experience in exchanges, payments, or ledger systems. A strong understanding of distributed systems like Kafka, PostgreSQL, and Redis is also important.