I build systems
that actually get used.

Custom management system for a real accounting firm ("Estudio JF"): clients, obligations, cash & banks, and client communication — running in production since August 2026.

• Design system built on Tailwind CSS v4 with OKLCH tokens — teal brand accent, full light/dark theme, and a dedicated color language for obligation states (paid, pending, overdue, waived...).
• Java 21 / Spring Boot backend on AWS Elastic Beanstalk (Docker), PostgreSQL on Supabase; React + Vite frontend, fully bilingual (Spanish/English) with i18next.
• Multi-factor authentication, role-based access (Admin, Treasury, Data Entry), and automatic 8-hour inactivity logout.
• Automatic email and WhatsApp reminders for obligations coming due.
• CI/CD with GitHub Actions and an end-to-end suite with Playwright before every deploy.

Buy-and-sell marketplace with user accounts, per-seller listings and subscription plans — built with Redux Toolkit and a fully bilingual interface (i18next, ES/EN).

• Complete REST API (Express) with JWT authentication and per-user product management.
• Subscription plans, protected endpoints and public queries, with category charts (Chart.js).
• Form validation with Joi + React Hook Form; toast notifications; MongoDB Atlas as the database.

Android app to log everyday activities and track time spent on each one, with history, reports and a live map of registered users.

• Built with Ionic Framework + Capacitor over a native shell, packaged in Android Studio (debug APK included in the repo).
• Activity log with duration and date, list view with date filters (last week / last month / all-time).
• Usage report screen (total time, daily average) and a live map built with Leaflet.

Toll-road simulation: an admin panel emulates vehicle crossings at a tollbooth, while owners track their balance, vehicles and crossing history in real time.

• Admin side: emulate a crossing by tollbooth, license plate and time; assign discounts ("bonificaciones"); change owner status.
• Owner dashboard: current balance, assigned discounts, registered vehicles, crossing history and system notifications.
• Live updates pushed with Server-Sent Events — no polling, no page refresh needed.
• Java/Spring Boot backend with MySQL; vanilla JS frontend rendered server-side per view.