Backend & Smart Contract Engineer
Solidity/EVM · Java/Spring · TypeScript/Node · Production Web3 systems · Real-world workflow logic

I build production-oriented backend systems, smart contracts, and Web3 integrations.

My background combines industrial automation, backend engineering, and blockchain development. That gives me a practical systems mindset: model the real workflow first, keep state transitions explicit, handle edge cases, and design software around reliability, permissions, timing, and failure modes.

Current technical focus:

• Backend systems: Java/Spring Boot, TypeScript/Node.js, REST APIs, PostgreSQL, authentication, OpenAPI, CI/CD
• Smart contracts: Solidity, Foundry, Hardhat, EVM, ERC standards, access control, state machines, testing
• Web3 integrations: wallets, contract interactions, tokenized workflows, on-chain/off-chain boundaries
• Real-world workflows: roles, permissions, deadlines, KPIs, certificates, incentives, traceability
• Industrial systems thinking: automation, controls, OT/IT integration, operational constraints, debugging under real-world pressure

Smart-contract-backed aviation workflow built during Decode Travel Barcelona with Camino Network × Vueling. The project models aircraft turnaround operations through task ownership, completion states, SLA/deadline logic, KPI computation, certification, and ERC-721 reward badges.

What it demonstrates: smart contracts as state machines for real-world operational workflows. Focus: Solidity · TypeScript · Camino Network · IPFS · ERC-721 · workflow state · operational process modeling Repo: https://github.com/aanit-app/decode-travel-with-vueling

Location-based NFT passport concept for Fallas in Valencia. Visitors claim checkpoint stamps by scanning QR/NFC on-site; the contract verifies EIP-712 signed vouchers instead of storing physical location data on-chain.

What it demonstrates: on-chain/off-chain boundary design, signed claims, replay protection, and privacy-aware presence workflows. Focus: Solidity · Foundry · ERC-1155 · EIP-712 · signed vouchers · replay protection · QR/NFC flow Repo: https://github.com/alsaecas/fallas-passport-1155

Production-style staking system where users stake a fixed amount of ERC20 tokens and claim ETH rewards by period. Includes admin flows, reward funding, custom errors, events, scripts, and security-focused testing.

What it demonstrates: reward accounting, secure token handling, admin boundaries, and Foundry-based contract validation. Focus: Solidity · Foundry · SafeERC20 · reentrancy protection · rewards · test coverage · scripts Repo: https://github.com/alsaecas/erc20-staking-eth-rewards

Solidity/Foundry smart contract system for multiple ETH savings plans with unlock times, early-withdraw penalties, treasury routing, pause controls, and security tests.

What it demonstrates: time-based contract logic, withdrawal constraints, treasury routing, and production-style safety controls. Focus: Solidity · Foundry · time locks · penalties · pausable flows · reentrancy protection · fuzz testing Repo: https://github.com/alsaecas/savings-bank-pro-foundry

On-chain bounty marketplace prototype with ERC20 rewards, escrowed bounty creation, work submissions, winner selection, deadline handling, cancellation flows, and payout execution.

What it demonstrates: marketplace state design, escrow logic, deadline-driven flows, and clear on-chain payout rules. Focus: Solidity · OpenZeppelin · ERC20 · escrow · marketplace logic · deadline-based flows Repo: https://github.com/alsaecas/Chain-Bounty-Marketplace

Solidity · Foundry · Hardhat · EVM · ERC-20 · ERC-721 · ERC-1155 · OpenZeppelin · EIP-712 · IPFS · DeFi primitives · wallet integrations

Java · Spring Boot · Node.js · TypeScript · REST APIs · PostgreSQL · MongoDB · Keycloak · OpenAPI/Swagger · Docker · GitHub Actions · GitLab CI/CD

React · TypeScript · Web3 wallet flows · marketplace features · KYC/user verification flows · Web2/Web3 integrations

PLCs · SCADA · OT/IT integration · automation and controls · automotive production environments · operational reliability

• Model the real workflow before choosing the technical design.
• Keep contract and API state transitions explicit.
• Treat authentication, wallets, providers, signatures, and external data as reliability boundaries.
• Prefer simple, testable architectures over unnecessary complexity.
• Use Web3 where it adds traceability, incentives, automation, or verifiable state — not as decoration.
• Document trade-offs clearly: assumptions, admin trust, upgrade paths, limitations, and production-hardening steps.

• Portfolio: https://www.alsaecas.dev/
• LinkedIn: https://www.linkedin.com/in/alejandrosaezc/
• GitHub: https://github.com/alsaecas