Descripción de la oferta
About the roleTodos los candidatos deben asegurarse de leer atentamente la siguiente descripción del puesto y la información antes de enviar su solicitud.We are seeking aSenior Blockchain & Backend Engineerto help maintain and evolveDebita by Neitec , our on-chain asset-based private credit infrastructure. This role combines production smart contract engineering with backend integration work across Web3 infrastructure, payment rails, custody providers and off-chain financial systems.The ideal candidate has already deployed and maintained smart contracts handling real-world capital, understands the full lifecycle from testnet to mainnet, and is comfortable building the backend services required to connect on-chain financial logic with APIs, databases, wallets and settlement flows.RequirementsFluent Spanish is required, as the role involves working closely with Spanish-speaking teams and stakeholders.The candidate must be based in Spain, preferably in Madrid, or willing to work within the Spanish time zone.This is NOT a junior position. We need someone who has:Deployed and maintained smart contracts handling real-world capital in productionExperienced the full lifecycle of blockchain projects from testnet to mainnetDebugged critical production issues under pressureMade architectural decisions that impact security and scalabilityKey distinction: You'll split your time 50/50 between:Smart Contracts & SDK Layer (EVM, Solidity, TypeScript SDK)API Integration Layer (Backend services consuming Web3 infrastructure)Core responsibilities1. Smart contract development & maintenance (50%)Production contract managementMaintain and upgrade existing bond issuance contractsDeploy new bond instances to mainnet following strict security protocolsMonitor on-chain operations and respond to incidentsCoordinate with auditors for security reviews before major upgradesFinancial logic implementationImplement complex amortization schedules (French, bullet, hybrid models)Design settlement mechanisms (atomic on-chain vs hybrid off-chain)Build compliance enforcement at the smart contract level (KYC/AML whitelisting)Integrate with Chainlink Automation for scheduled operations (interest payments, redemptions)SDK developmentMaintain TypeScript SDK used by APIGenerate and version ABIs, TypeChain bindings, and contract interfacesWrite integration tests ensuring SDK behavior matches contract stateDocument breaking changes and coordinate releases with API team2. Web3 API integration (50%)Backend servicesIntegrate SDK into NestJS API servicesBuild reliable transaction management (nonce handling, gas estimation, retry logic)Design off-chain balance registries synchronized with on-chain statePayment rails & custody integrationsIntegrate with fiat on/off ramp providers (bank accounts, payment processors)Connect payment rails: crypto transfers, SEPA, ACH and local payment methodsIntegrate with liquidity providers and custody solutions (MPC wallets, institutional custodians)Build synchronization mechanisms between on-chain state and off-chain legacy systemsCoordinate atomic or hybrid DVP (Delivery vs Payment) settlements across chains and railsHandle wallet management, signing flows, and key rotation strategiesImplement transaction batching and gas optimization at API levelTechnical requirementsBlockchain / Smart ContractsProduction solidity experience2+ years writing production SolidityDeployed contracts managing real fundson mainnetHandled production incidents (reverted transactions, gas spikes, oracle failures)Experience with upgradeable contracts (UUPS, Transparent, or Beacon proxies)Deep understanding of EVM internals (storage layout, gas optimization, assembly when necessary)Concrete skillsWrite gas-efficient Solidity following best practicesDebug failed transactions using Tenderly, block explorers, or local forkingPerform upgrades on live contracts without downtime or data lossImplement custom error handling, events, and role-based access control (OpenZeppelin)Understand reentrancy risks, front-running, and common attack vectorsTools & frameworksFoundry(primary) or Hardhat (legacy support)OpenZeppelin Contracts (v5.x upgradeable suite)Chainlink Automation (keeper-compatible contracts)Backend developmentTypeScript/Node.js3+ years building production Node. xcskxlj js servicesExperience with NestJS or similar enterprise frameworksProficient in ethers.js v6 (contract interactions, wallet management, event parsing)Async/await patterns, error handling, and retry mechanismsDatabase & state managementPostgreSQL for off-chain data (transactions, balances, audit logs)Understanding of eventual consistency in blockchain-to-database syncExperience with migration scripts and schema versioningAPI designRESTful API design for financial operations (idempotency, validation)WebSocket streams for real-time blockchain eventsRate limiting and authentication for sensitive endpointsError handling that doesn't leak private keys or internal stateIntegration & traditional financeBridge blockchain with legacy systemsExperience integrating blockchain with traditional banking/payment infrastructureUnderstanding of fiat on/off ramps(convert crypto fiat via bank accounts)Knowledge of payment rails:SEPA (Europe), ACH (US), wire transfers, local payment methods (SPEI/Mexico, Pix/Brazil, FedNow, etc.)Bank account integration experience (APIs for deposits, withdrawals, reconciliation)Custody provider integrations (MPC wallets, institutional custodians, key management services)Liquidity provider coordination (ensuring sufficient funds for settlements)On-Chain / Off-Chain state synchronizationDesign systems that maintain consistency between blockchain state and database stateHandle eventual consistency and reconciliation between on-chain events and off-chain recordsBuild idempotent operations that can safely retry without double-spending or data corruptionMonitor and alert on synchronization drift (on-chain balance ≠ database balance)Delivery vs Payment (DVP) coordinationAtomic DVP: On-chain smart contract settlement (payment + delivery in single transaction)Hybrid DVP: Coordinate on-chain delivery with off-chain payment (via bank transfer, custody ledger)Handle multi-leg settlement flows (bond issuance → fiat payment confirmation → token delivery)Implement rollback/refund logic when one leg of DVP failsExperience with escrow mechanisms, multi-signature approvals, or atomic swapsConcrete skillsIntegrate with payment processor APIsHandle currency conversion and multi-currency accountingDesign webhooks and callbacks for asynchronous payment confirmationUnderstand regulatory requirements for AML/KYC in payment flowsFinancial protocols understandingCapital markets basicsBond lifecycle: issuance → coupon payments → principal redemption → maturity/defaultAtomic DVP (fully on-chain: smart contract ensures simultaneous delivery + payment)Hybrid DVP (on-chain delivery coordinated with off-chain payment via bank transfer or custody ledger)Escrow and multi-signature approval flowsAmortization schedulesRoles managementTokenization conceptsSecurity token standards (ERC-20 with compliance hooks)On-chain vs off-chain compliance (hybrid models)Custodial vs non-custodial wallets in institutional contextNice-to-have experienceAdvanced blockchainMulti-chain deployments (experience with 2+ EVM chains in production)MEV awareness and mitigation strategies (private mempools, Flashbots)Gas optimization at scale (batch operations, signature aggregation)Experience with account abstraction (ERC-4337) or smart contract walletsDomain experienceBuilt or maintained aReal-World Asset (RWA) protocolExperience withSecurity Token standards (ERC-3643, ERC-1400)Worked unregulated fintech (securities, payments, custody)Integrated with institutional custody
