Ya Está Pago — Full-Stack Payment Verification Platform.
Software Developer & Architect · yaestapago.co
Figure 1. Ya Está Pago (yaestapago.co) product concept — real-time payment confirmation dashboard. (Image generated with AI.)
Figure 2. YEP brand identity — the isotype and wordmark used across the web, mobile and desktop apps.
Overview
Ya Está Pago (yaestapago.co) is a payment-verification platform for merchants in Colombia that confirms in real time when a customer's transfer has actually arrived. Instead of trusting a screenshot at the counter, the business receives an automatic, verified confirmation. The product listens to bank notifications (Nequi, Bancolombia, Daviplata), extracts the transaction data from payment receipts using OCR and AI, and integrates with WhatsApp so businesses can operate directly from the messaging channel they already use.
System Architecture
The system is organized as a multi-repository ecosystem orchestrated through a central development environment (Git submodules + Docker Compose). It is composed of several independent, separately deployable services that communicate over a documented REST API:
- Web app (frontend): Angular 21 single-page application in TypeScript, tested with Vitest. Merchant dashboard to manage business accounts, locations, notifiers and view verified transactions.
- API core (backend): NestJS on Node.js 20 with MongoDB Atlas (Mongoose), JWT authentication and bcrypt password hashing. Handles auth, business accounts, notifications, transaction extraction and the WhatsApp Cloud API webhooks.
- AI + OCR pipeline: AWS Textract performs OCR on receipt images and the OpenAI Responses API (GPT-4.1-mini) structures the extracted transaction data, with per-request timing and cost diagnostics.
- Mobile notifier (Android): Flutter/Dart app using Android's NotificationListenerService to capture bank notifications, a persistent encrypted queue with idempotent retries, and WorkManager for background heartbeat and sync.
- Desktop notifier (Windows): .NET 8 / C# application that forwards banking notifications from the desktop.
- Infrastructure & DevOps: Dockerized local environment, deployment to AWS Elastic Beanstalk, per-service CI/CD pipelines, and automated testing (Vitest).
Technologies Used
Engineering Role & Team
I designed and built the platform end-to-end — from the multi-service system architecture and backend to the DevOps pipeline and automated testing — working alongside my colleagues: