Mathematician • Mobile Engineer • Backend Engineer • Blockchain Developer

I'm a Senior Full Stack Engineer and Mathematician with experience building fintech platforms, mobile applications, backend services, and blockchain solutions.

Throughout my career, I've worked on:

• Fintech platforms and payment systems
• Mobile applications with React Native
• Scalable backend architectures with NestJS and Node.js
• Blockchain and Web3 applications
• Smart contract integrations
• REST APIs and distributed systems
• Health analytics and wearable integrations

My background in Mathematics allows me to approach software engineering with strong analytical thinking, structured problem-solving, and system design principles.

Full Stack Developer

• React Native mobile applications
• NestJS backend services
• Health analytics
• Wearable integrations
• Wellness scoring systems

Full Stack Developer

• Fintech applications
• Banking integrations
• Payment systems
• Blockchain services
• Financial APIs

Frontend & Blockchain Engineer

• Web3 applications
• Smart contract integrations
• DeFi infrastructure
• Blockchain frontend architecture

I have worked as:

• JavaScript Instructor
• Teaching Lead
• Programming Mentor
• Mathematics Instructor

Over the years, I have mentored and taught more than 5,000 students in software engineering, mathematics, and programming.

• React Native Architecture
• NestJS Backend Systems
• Fintech Infrastructure
• Blockchain & Web3 Applications
• Smart Contract Security
• DeFi Protocols
• System Design
• High-Performance APIs

• LinkedIn: linkedin.com/in/andresvelasqueztrujillo
• GitHub: github.com/andresf2448
• Email: andresf2448@gmail.com

A selection of blockchain, DeFi and full stack applications focused on smart contracts, Web3 infrastructure and decentralized systems.

Implementation of a DeFi platform focused on governance, vault infrastructure, treasury systems, and on-chain operational controls, contributing across smart contracts, frontend architecture, and protocol security.

• Smart contract development in Solidity
• Vault architecture and governance systems
• Modular frontend implementation using React and TypeScript
• Web3 integration and hook-based frontend architecture
• Treasury systems and operational control development
• Unit testing, fuzzing, stateful and stateless testing
• Security analysis using Slither and Aderyn
• Protocol architecture optimization, maintainability, and scalability improvements

A decentralized healthcare platform built with Solidity smart contracts, allowing laboratories and users to interact through blockchain-based subscriptions and healthcare services.

• Subscription-based smart contracts
• ERC20 token integration
• Laboratory-created specialized services
• MetaMask wallet connectivity
• Decentralized healthcare service management

NFT platform where users can mint, manage and transfer ERC721 NFTs directly on-chain.

• NFT minting
• ERC721 ownership transfers
• MetaMask integration
• On-chain avatar generation
• Decentralized NFT interactions

Blockchain voting application designed to guarantee transparency, immutability and one-vote-per-user participation.

• Candidate registration
• Immutable election records
• One-vote-per-user validation
• Real-time vote counting
• IPFS integration

A decentralized lottery system where users can purchase tickets, interact with token rewards and participate in on-chain winner selection.

• On-chain lottery participation
• Token purchase system
• Random winner selection
• Ticket management
• Token withdrawal functionality

Exchange platform connected to the Stellar blockchain network for fiat and cryptocurrency asset trading.

• Fiat & crypto exchange
• Stellar blockchain integration
• Real-time operations
• Financial asset management
• Secure transaction workflows

Full Stack SPA using React, Redux, Node.js, Express, Sequelize and PostgreSQL.

Responsive landing page built with JavaScript, HTML, CSS and jQuery.