GoodPegg — Client Work
Full stack contributor on a Norwegian healthcare learning platform and a business messaging product.
Contracted by GoodPegg to contribute full stack development across two products. KasiApp is a Norwegian medical learning platform featuring 3D virtual patient simulations and interactive clinical case studies — built with React and Firebase. GoodPegg's core product is a business messaging platform integrating with the WhatsApp Business API for campaign management and automated messaging workflows.
Both products required features across the full stack — from frontend UI to backend integrations — and the client needed a developer who could move across layers without handoff delays.
Full stack contributor — implemented client-specified features across frontend and backend on both products, working within existing codebases and coordinating with the client team.
Engineering challenges
WhatsApp Business API Integration
WhatsApp Business API has strict template approval requirements, rate limits, and webhook verification requirements that make integration more complex than a standard messaging API.
Implemented the full webhook verification flow, template management system, and rate-limit-aware message dispatch with retry logic. Message delivery status is tracked per recipient via webhook callbacks.
3D Medical Simulation (KasiApp)
Interactive 3D patient simulations in the browser needed to be performant on standard hardware without requiring specialized graphics capabilities.
Implemented 3D scenes using Three.js with level-of-detail management and lazy loading for simulation assets. Firebase handled real-time state for interactive case progression.
Architecture
What we built
3D Virtual Patient Simulation
Interactive 3D clinical simulations for medical learning — case-based scenarios with branching outcomes based on learner decisions.
WhatsApp Campaign Management
Business messaging campaigns with template management, recipient targeting, scheduled delivery, and per-recipient delivery tracking.
Webhook-Based Delivery Tracking
WhatsApp message delivery status updated in real time via Meta webhook callbacks — sent, delivered, read status per recipient.
Technical highlights
Three.js 3D simulation with LOD management for performance on standard hardware
Meta WhatsApp Business API with template approval workflow and webhook verification
Firebase real-time database for interactive case state in KasiApp
Rate-limit-aware message dispatch with exponential backoff retry
The impact
Two products
Contributed across
Live
Both products in production
WhatsApp API
Full integration built
3D
Medical simulations implemented
Business outcomes
Feature Delivery Across Two Products
Client received full stack feature delivery across two distinct products without needing separate frontend and backend contractors.
Lessons learned
WhatsApp Business API template approval timelines need to be accounted for in project planning — rejection and resubmission can add weeks
Contributing to existing codebases requires understanding conventions before adding features — time spent reading is not time wasted