Adrian Castillo
Backend & Platform Engineer
Domain-Driven Design · AI Infrastructure
Colima, México · [email protected] · github.com/rodacato · linkedin.com/in/rodacato · notdefined.dev
Backend-heavy engineer with 17+ years shipping production systems — fintech payments, HIPAA healthcare, crypto exchanges, eCommerce, IoT/telematics, and AI/LLM infrastructure. Core stack Ruby/Rails and Node.js/TypeScript, with Rust in production for real-time device communications. Designs around Domain-Driven Design, hexagonal architecture, and event-driven patterns; builds AI tooling rather than just consuming it. Prefers boring infrastructure that works over clever infrastructure that doesn’t.
Skills
- Backend
- Ruby · Ruby on Rails · Sinatra · Node.js · Rust · API design (REST & GraphQL) · Event-driven systems
- Architecture
- Domain-Driven Design · Hexagonal architecture · Clean architecture · Microservices & modular monoliths · dry-rb / dry-system
- Frontend
- JavaScript · TypeScript · React · React Native
- Data & messaging
- PostgreSQL · MySQL · Redis · RabbitMQ
- Cloud & DevOps
- AWS (EC2, Lambda, VPC) · Terraform · Docker · Kamal · CI/CD
- Practices
- TDD / BDD (RSpec) · Agile / XP · Technical leadership & mentoring
Experience
Encontrack Jun 2025 – Present
Senior Software Engineer (Consultant) Remote
- Core software team for a vehicle-tracking platform covering 200,000+ vehicles across México — maintaining the device-communications and message-processing systems.
- iotHub — the Rust processing layer that ingests and handles real-time device communications.
- DeviceManager (Rails) — equipment inventory and command dispatch; led the team building it.
- Encontrol — React Native apps with a Node/Express backend; lead engineer.
- DeviceManager and Encontrol both started as prototypes and consolidated into production internal systems and products by proving their value in daily operations.
Rust · Ruby on Rails · Node.js · Express · React Native
Monato Mar 2025 – Mar 2026
Senior Engineer (Consultant) Remote
- Led the audit, architectural redesign, and optimization of a cloud-based bill-payments platform (Ruby API).
- Designed a DDD + hexagonal + event-driven architecture; migrated the API V1 → V2 behind a canary proxy for zero-downtime rollout.
- Established a formal technical-proposal process — authored and documented 17 FIPs (Finco Improvement Proposals) — to guide engineering decisions across the team.
- Implemented a persisted Event Store for domain events, dependency injection with dry-system, and OAuth 2.0 for the V2 API.
- Set up an E2E regression suite and a DevContainer to streamline team onboarding.
Ruby · dry-rb · dry-system · DDD · Hexagonal · Event-Driven · OAuth 2.0
Invoy Sep 2019 – Mar 2025
Senior Full Stack Engineer Irvine, CA (Remote)
- Core team scaling a HIPAA healthcare platform to 10x traffic — multi-tenancy, real-time availability, strict security on medical data.
- Migrated infrastructure from Heroku to AWS — better performance and cost.
- Evolved architecture: independent services → microservices → consolidated scalable monolith.
- Implemented HIPAA-compliant safeguards for sensitive medical data.
- Built and maintained core Sinatra/Ruby APIs and React frontends.
Ruby · Sinatra · Sequel · dry-rb · React · AWS · Terraform · Docker
michelada.io Feb 2018 – Sep 2019
Senior Software Engineer · Team Lead Colima, México
- Led a team of 5 building a cryptocurrency exchange; RabbitMQ for order-book processing.
- Built a reporting microservice over a legacy system with JasperReports.
- Worked directly with clients; established reading clubs, blog posts, and internal training.
Ruby on Rails · Sinatra · React · RabbitMQ
Maker 2017 – 2019 (two engagements)
Senior Software Engineer San Francisco Bay Area
- Led a Rails version upgrade for security and maintainability; designed the hiring eval and hired 2 senior Rails engineers.
- Built a Rails Engine generating email templates from marketing pages (MJML + Inkscape), tuned for Outlook.
Ruby on Rails · React · Elasticsearch · MJML · AWS Lambda
eFORMance Jul 2017 – Mar 2019
Senior Software Engineer Edmonton, Canada (Remote)
- Rewrote an underperforming Rails prototype into a production B2B SaaS; refocused scope to core needs.
- Integrated Kendo UI; deployed on DigitalOcean for cost efficiency.
Ruby on Rails · Node.js · Kendo UI · DigitalOcean
Pay By Group Apr 2016 – May 2018
Senior Software Engineer San Francisco Bay Area
- Led the transition to an API-first model for group-payment integrations.
- Migrated payments to Stripe Connected Accounts — compliance and efficiency.
- Introduced Domain-Driven Design for the payment domain; Sinatra APIs; XP practices.
Ruby · Sinatra · Stripe · DDD
Grupo Regalii (now Arcus, a Mastercard company) Feb 2016 – May 2016
Senior Software Engineer Remote
- Maintained and improved cross-border payment APIs; private network links with providers in El Salvador & Costa Rica.
- AWS VPC setup for secure provider communication.
Ruby on Rails · AWS (VPC)
MagmaLabs (formerly Crowd Interactive) Oct 2015 – Feb 2016
Senior Software Engineer Colima, México
- PayPal integration for eCommerce refunds; return-label automation; Heroku infrastructure.
Ruby on Rails · PayPal · Heroku
Crowd Interactive Mar 2013 – Oct 2015
Senior Software Engineer · Team Lead Colima, México
- Led the team for Igobono, a high-demand social marketplace.
- Built a Sinatra & Angular API for Red Bull’s photo-sharing media system.
- Balanced Heroku & Engine Yard; direct client engagement on product and feasibility.
Ruby on Rails · Sinatra · AngularJS · Heroku · Engine Yard
Freshout Nov 2010 – Mar 2013
Backend & DevOps Engineer Guadalajara, México
- Built Rails backends for eCommerce, marketing, and social platforms.
- Managed Engine Yard / Rackspace infra; CI pipelines with RSpec.
Ruby on Rails · Chef · Engine Yard · Rackspace · RSpec
Crowd Interactive Dec 2008 – Nov 2010
Agile Web Developer Colima, México
- Transitioned from PHP/Flex to Ruby on Rails; Flex UI for AI-powered assistants and Google Ads monitoring.
- PHP support for the Barack Obama Foundation website; built the Modcloth eCommerce platform.
PHP · Flex · Ruby on Rails
Secretaría de Salud Dec 2007 – Dec 2008
Web Developer Colima, México
- First professional role: a digital medical-records system replacing manual workflows.
- Built a parallel prototype for a smooth legacy transition (PHP, Flex 3).
PHP · Flex 3
Education
B.E. Telemática
Universidad de Colima · 2003 – 2007
Awards
Rails Rumble 2015 — Winner
Languages
Spanish — Native
English — Professional working
Beyond code
Woodworking & DIY
Board games & miniature painting
Boxing
Recommendations
What I value most about Adrián is his ability to elevate a team's performance. He not only implemented profound architectural improvements and solidified SOLID, DDD and Hexagonal Architecture principles in our codebase, but he did so with a strategic vision focused on empowering the internal team. If you are looking for someone who not only solves complex technical problems but also strengthens your company's engineering culture, Adrián is the right person.
Adrian is an absolute pleasure to work with. He is very passionate, a great collaborator, and a very thoughtful and consistent developer that cares and thinks deeply about the user. He knows how to write great code, but he shines by collaborating with multiple teams and solving business and user problems. This is why everyone loves to work with him. Any team that gets to bring him on is set to win.
Adrian is fast and thoughtful when finding a solution needed by the business. He is very open to sharing his architecture proposals and his concerns with new features because he wants them done properly the first time. When working with less experienced developers, he is very patient and respectful. His Ruby, React, SQL, and problem-solving skills make him a valuable asset.