Andrés Felipe Velásquez Trujillo — Ruby on Rails Developer

Expertise in Full Stack Web (5.0 yr.).

Last verified on August, 2026

Core Skills

Bio Summary

Ruby on Rails expert with 4+ years in fintech backend systems processing $2B+ in transfers, skilled in Active Record, Sidekiq, Redis caching.
Proficient in Solidity smart contract development and security auditing using Slither, Foundry; built 28+ DeFi contracts.
Experienced in full stack development with React, React Native, Next.js, NestJS, and Hotwire for scalable web and mobile apps.
Strong CI/CD, automated testing (RSpec, FactoryBot, Playwright), and AI-assisted development using Claude Code, Codex, and RAG pipelines.
Mathematics degree with top honors, advanced blockchain security certification, and ongoing AI/ML training emphasizing MLOps and scalable pipelines.

Technical Skills

Programming Languages	JavaScript, Solidity, TypeScript
JavaScript Libraries and Tools	Ethers.js, Expo, React Native, Web3.js
JavaScript Frameworks	NestJS, Next.js, React
AI & Machine Learning	RAG
Ruby Frameworks	Ruby on Rails
Ruby Libraries and Tools	Sidekiq
Databases & Management Systems / ORM	PostgreSQL, Redis
Cloud Platforms, Services & Computing	AWS, GCP
Deployment, CI/CD & Administration	Active Directory, CI/CD
Virtualization, Containers and Orchestration	Docker
Blockchain and Decentralized Software	Ethers.js, Foundry, Hardhat, OpenZeppelin, Truffle, Viem, WAGMI
Version Control	Git
QA, Test Automation, Security	Playwright, RSpec, Testing Library
File Systems, Storage	Protobuf
Other Technical Skills	AD, Claude Code, FactoryBot, Hotwire

Work Experience

Full Stack Developer - Vitality+ (Vitality+ Platform Enhancements)

Duration: Jun 2026 – Aug 2026

Summary: Maintained and extended the Vitality+ health and wellness platform, integrating wearable devices and Google services to enhance AI-driven wellness recommendations for users.

Responsibilities:

Maintained and extended existing platform functionality across backend and mobile.
Built wearable device integrations (Whoop, Oura) to expand connected devices.
Developed Google Health and Google Calendar integrations for personalized AI wellness recommendations.
Utilized Claude Code and git worktrees to accelerate delivery and maintain codebase consistency.
Developed mobile features using React Native and Expo on a NestJS backend.

Technologies: Ruby on Rails, React Native, Expo, NestJS, Claude Code, Google Health API, Google Calendar API

Full Stack Web3 Blockchain Engineer - Investment Armendariz (DeFi Governance and Vault Protocol)

Duration: Dec 2025 – May 2026

Summary: Designed and developed a decentralized finance governance and vault protocol with smart contracts and an administrative backend, ensuring security and efficient management.

Responsibilities:

Designed, built, and audited 28 Solidity smart contracts for DeFi governance and vault protocol.
Identified and mitigated security vulnerabilities such as reentrancy and denial-of-service.
Developed an administrative backend in Ruby on Rails with a Hotwire admin dashboard.
Set up CI/CD pipelines and wrote automated tests for backend and frontend.
Implemented a Retrieval-Augmented Generation (RAG) pipeline for internal knowledge retrieval.
Used AI tools Claude Code and Codex to enhance daily workflow.

Technologies: Solidity, Ruby on Rails, Hotwire (Turbo + Stimulus), Slither, Aderyn, Foundry, Testing Library, Playwright, Pinecone, Claude Code, Codex, React, TypeScript

Full Stack & Blockchain Developer (Rails, React, Solidity) - Freelancer.com (Various Client Projects)

Duration: Jul 2021 – May 2026

Summary: Delivered multiple projects involving backend APIs, blockchain smart contracts, and decentralized applications across various industries including warehouse management, healthcare, NFT marketplaces, and decentralized voting.

Responsibilities:

Built Ruby on Rails REST APIs for user management, wallet associations, subscriptions, and metadata.
Developed Solidity smart contracts (ERC-20/ERC-721) using OpenZeppelin standards.
Created dApp frontends with React.js and integrated Web3.js/Ethers.js/MetaMask.
Utilized AI engineering agents like Codex to increase delivery speed across diverse client stacks.

Technologies: Ruby on Rails, PostgreSQL, Solidity, OpenZeppelin, React.js, Web3.js, Ethers.js, MetaMask, Codex

Full Stack Developer (Fintech & Crypto Integrations) - Vita Wallet (Vita Wallet Fintech Platform)

Duration: Aug 2021 – Nov 2025

Summary: Owned core backend architecture for a fintech platform processing over $2B USD in transfers, integrating international banks and crypto exchanges to support high-volume liquidity flows and enterprise payroll payments.

Responsibilities:

Managed backend architecture with Ruby on Rails including Active Record data modeling, Sidekiq background jobs, and Redis caching.
Led adoption of Strategy pattern for international bank integrations, reducing integration time significantly.
Built and maintained payment provider integrations with banks and crypto exchanges (Binance, Circle).
Developed batch payment infrastructure for enterprise payroll in crypto and fiat with React and React Native frontends.
Maintained automated test suites with RSpec and FactoryBot to reduce regressions.
Used Codex AI tools to speed up implementation, debugging, and code review.

Technologies: Ruby on Rails, Active Record, Sidekiq, Redis, React, React Native, RSpec, FactoryBot, Binance API, Circle API, Codex

Full Stack & Blockchain Programming Instructor - Coderhouse (Full Stack and Blockchain Curriculum Delivery)

Duration: Jan 2020 – Jun 2024

Summary: Designed and delivered comprehensive technical curriculum on Full Stack and Blockchain development to approximately 20,000 students, mentoring through real-world projects and collaborative environments.

Responsibilities:

Designed and delivered curriculum covering React, Node.js, PostgreSQL, REST APIs, and blockchain development.
Mentored students through projects, code reviews, and bootcamp collaboration.

Technologies: React, Node.js, PostgreSQL, REST APIs, Solidity

Education

Mathematics — Universidad de Antioquia
Graduated with first-place recognition for the defense of degree thesis in Mathematical Logic. Strong foundation in analytical reasoning, abstraction, and structured problem-solving.
Aug 2014 – Jan 2021

Certification

AI Engineer / Machine Learning Developer (in progress) — Anyone AI
Intensive bootcamp in Artificial Intelligence and Machine Learning: Scikit-Learn, TensorFlow, PyTorch, ETL pipelines, MLOps (Docker, APIs, AWS/GCP).
Aug 2026 – Feb 2027
Smart Contract Security | Blockchain Engineer — Cyfrin Updraft
Advanced training in smart contract auditing, fuzzing, invariant testing, and protocol-level risk analysis.
Jan 2024 – Jun 2025
English Language and Literature — London School of Commerce
Professional communication, technical documentation comprehension, and collaboration with international teams in English.
May 2025 – Aug 2025

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