Lead Software Engineer · Systems Builder · Web & Mobile Application Developer
Great software should be a catalyst for value, not a source of complexity. My approach is rooted in strong engineering discipline ensuring that every system is as scalable as it is reliable.
In a world of digital noise, software should solve real problems and create meaningful outcomes. My approach is rooted in systems thinking and clean architecture disciplines that turn raw code into reliable, scalable infrastructure. I design and deliver the web and mobile applications that make those outcomes possible, where every feature is intentional, every system is built to last, and every product quietly does what it was meant to do: work seamlessly for the people who rely on it.
Beyond the build, I see software as a long term responsibility. It's not just about shipping features, but about shaping experiences that endure, systems that can evolve, adapt, and remain clear even as complexity grows. I value clarity over cleverness, consistency over shortcuts, and purpose over noise, ensuring that what we create today continues to make sense tomorrow.
20+ Apps Built
5+ Happy Clients
4+ Years Experience
1500+ Cups of Coffee
Experience
Co-Founder & CTO — GeoTech
Metro Cebu · Hybrid · Feb 2026 - Present ·
Co-founded GeoTech and lead its technical direction as CTO, owning the architecture, engineering standards, and product roadmap.
Building and leading the engineering effort across web and mobile, setting up the stack, infrastructure, and delivery practices from the ground up.
Driving project management and team leadership, coordinating priorities across a lean, cross-functional team to ship reliably.
Translating product strategy into scalable, maintainable systems using clean architecture and modern full-stack tooling.
Technologies: Project Management, Leadership, System Architecture, Full-Stack Development, Product Strategy
Head of Tech Department — UA - Underground Apparel
Metro Cebu · Hybrid · Sep 2025 - Present ·
Head of Tech Department
Jun 2026 - Present ·
Leading the technology department, setting technical direction and engineering standards across mobile, web, and internal systems.
Managing and mentoring the engineering team while owning delivery, code quality, and architecture decisions.
Driving the product and platform roadmap, from the e-commerce app to the tools and infrastructure that support it.
Partnering with leadership on technical strategy, hiring, and scaling the tech organization.
Technologies: Engineering Leadership, Team Management, System Architecture, Product Strategy, E-Commerce, Delivery
App Developer
Sep 2025 - Jun 2026 · 10 mos
Spearheaded the mobile application development for iOS and Android.
Implemented Clean Architecture, the BLoC pattern, and Test-Driven Development (TDD) to build a scalable and robust codebase from the ground up.
Laid the groundwork for core e-commerce functionality, integrating the Shopify API for product catalogs, order processing, and user authentication.
Collaborated with the Chief Data Officer during planning and design to ensure a seamless, high-quality user experience.
Mobile App Developer — CQ Business Management Software
London, England · Remote · Sep 2025 - Present ·
Maintain and evolve key features for a live, cross-platform mobile application, strictly adhering to Clean Architecture and leveraging the BLoC/Cubit state management pattern.
Integrate and optimize connectivity with backend services via RESTful APIs, managing data flow, and utilizing dependency injection for robust system communication.
Ensure high code quality and efficiency across the codebase using modern tooling like Freezed (for immutable models) and Json Serializable (for data parsing).
Collaborate effectively with a distributed, international team (Philippines and UK), utilizing a flexible schedule to align on project deliverables and business hours.
Functioned as the sole developer responsible for the entire lifecycle of the application, from initial design and development to continuous maintenance and updates.
Designing and developing robust mobile application using Flutter, ensuring adherence to Clean Architecture principles for enhanced maintainability and scalability.
Implementing the BLoC (Business Logic Component) pattern to separate business logic from the UI, resulting in a well-organized and highly testable codebase.
Practicing Test Driven Development (TDD) to create comprehensive unit and widget tests, achieving a stable and reliable application with significantly increased test coverage.
Creating responsive and intuitive user interfaces with Flutter widgets, maintaining a strong focus on UX design principles to enhance user satisfaction and engagement.
Technologies: Mobile Application Development, Flutter, Dart, Mobile Applications, Test-Driven Development, Business Logic, Engineering, Clean Architecture Structure, Cross-functional Team Leadership, Leadership
Artificial Intelligence Trainer — Outlier
Remote · Freelance · Sep 2024 - Present · 1 yr
My role involves creating prompts and ensuring that they are detailed, specific and relevant to guide the AI toward a useful response.
Quality checking, tracing the factuality of responses, and analyzing the efficiency of the codes used by the AI, to ensure accuracy, optimal performance, and understanding of the reasoning process.
Guiding AI models through various projects, tackling diverse and complex coding problems, and ensuring continuous learning and improvement.
Analyzing and interpreting model performance to identify training deficiencies and opportunities for improvement from multiple modalities, including images, audio, or video.
Technologies: AI Prompting, Prompt Engineering, Multimodal Prompting
Freelancer — Upwork
Cebu, Central Visayas, Philippines · Remote · Aug 2022 - Jan 2024 · 1 yr 6 mos
Developed Flutter mobile applications for various clients with focus on clean code and user experience.
Collaborated with international clients to deliver high-quality mobile solutions.
Maintained consistent communication and project management throughout development cycles.
Technologies: Flutter, Dart
Web Developer Intern — Sun Asterisk Philippines
Cebu, Central Visayas, Philippines · Remote · Jul 2022 - Aug 2022 · 2 mos
Gained hands-on experience in web development using modern frameworks and technologies.
Participated in team projects and learned industry best practices for software development.
Developed skills in version control, project management, and collaborative development.
Completed training in full-stack development methodologies and agile practices.
Technologies: Django, Git, Agile Project Management, Asana, MySQL, ReactJs, Test Automation, Python (Programming Language), Web Development
Featured Projects
A selection of product builds where I led and handled the architecture, implementation, and delivery — applying software engineering principles to real-world use cases.
UA — Underground Apparel App
The official mobile e-commerce app for Underground Apparel, a Cebu-based streetwear brand — curated drops, immersive browsing, and secure checkout.
A subscription-based personal video platform for creator Joseph Sabello (Ungart) — a Flutter app and marketing site delivering weekly premium episodes. Live on iOS & Android.
Video catalog with featured carousel & search
In-app player with resume-watch progress
Subscriptions & in-app purchases for premium
AI mood-based recommendations (Gemini)
Comments, favorites & watch-later
Companion marketing website
Technologies: Flutter, Firebase, Cloudflare Stream, In-App Purchase, Next.js, Gemini AI
The cross-platform mobile companion for CQ (Custom Quoter) business management — a field-service app where technicians run jobs, schedules, timesheets, and client assets on the go. Live in production (UK).
Job management with tasks, checklists & work status
A comprehensive mobile application connecting patients with gynecologists, fostering a community for women's health, and streamlining administrative oversight.
Patient appointment booking & management
Doctor schedule management & e-consultations
Period tracker & cycle history
Community forums for health discussions
Admin dashboard for user verification
Multi-role authentication system
Technologies: Flutter, Firebase, BLoC, Cloud Firestore, Get It
A comprehensive digital marketplace connecting Customers, Farmers, and Agricultural Organizations with real-time chat, location services, and order management.
An intelligent, real-time bus booking and management platform with live tracking, seat selection, and multi-role support for passengers, drivers, and admins.
Real-time bus tracking & location sharing
Terminal & on-the-road booking options
Interactive seat selection system
In-app wallet for cashless payments
Driver earnings dashboard
Fleet management for administrators
Technologies: Flutter, Firebase, Google Maps, Provider, Geolocator
A personalized finance tracking application designed to empower users in managing their finances with precision, budgeting tools, and expense tracking.
Personalized expense tracking
Budget management & planning
Financial analytics & reports
Category-based expense organization
Goal setting & progress tracking
Data visualization with charts
Technologies: Flutter, SQLite, Provider, Charts, Local Storage
A full-stack toolkit spanning mobile, web, and the services behind them — with a strong focus on clean architecture, reliability, and maintainable delivery.
Mobile Engineering
Flutter
Dart
BLoC / Cubit
Freezed & JSON Serializable
REST APIs
Web & Full-Stack
TypeScript
React
Next.js
Tailwind CSS
Python
Backend & Data
Supabase
PostgreSQL
SQL
Firebase / Firestore
SQLite
Cloud & Services
Cloudflare
bunny.net
Resend
Vercel
Engineering Practices
Clean Architecture
Test-Driven Development (TDD)
System Architecture
Dependency Injection
Scalability & Maintainability
Frameworks & Libraries
TypeScript, React, Next.js, Flutter, Dart, Python, Firebase, Supabase, PostgreSQL, Cloudflare, bunny.net, Resend, Vercel, BLoC, Cubit, Clean Architecture, REST APIs, Freezed, Get It (DI), Dio, SQLite, Tailwind CSS
Education & leadership
Bachelor of Science in Computer Engineering
Cebu Institute of Technology – University, Cebu City · 2019 – 2023
Silver Medalist — CESAFI Robotics Tournament 2020
STEM — Science, Technology, Engineering, and Mathematics
Mindanao State University – Zamboanga Sibugay, Poblacion Buug · 2017 – 2019
Led the student government and represented the student body — advocating for student rights and interests, overseeing operations, and coordinating events and communication between students, administration, and faculty. Ensured student voices were heard while fostering a positive and engaging student experience.
Client Validation
Anonymized, verified feedback from engagements focused on architecture quality, delivery reliability, and product outcomes.
Rex consistently translated rough requirements into stable deliverables. Release confidence improved after he restructured the feature architecture and delivery sequence.
He combined architecture thinking with practical execution. We moved from fragmented implementation into a clear roadmap that made launches more predictable.
Rex takes ownership from planning through release. His structured approach reduced regressions and improved cross-team handoff quality.
Communication was clear, timelines were respected, and delivery quality held under pressure. The system became easier for internal teams to use and maintain.
Get In Touch
Planning a web app, mobile app, or complete software system? Let's discuss your goals and build something reliable together.