A hands-on engineering laboratory for exploring how modern payment systems are built, secured, deployed, and operated using the PayMongo Sandbox API.
Rather than focusing solely on integrating a payment gateway, this repository explores the architecture, security, infrastructure, and operational practices behind real-world payment systems.
The goal is not to build a production-ready e-commerce platform.
The goal is to understand the engineering decisions that make secure online payments reliable, scalable, and maintainable.
This repository aims to explore:
- Modern payment workflows using PayMongo Sandbox
- Secure checkout and payment processing
- Backend architecture and API design
- Webhook verification and event-driven communication
- Secure secrets management
- Transaction validation and duplicate payment prevention
- Order lifecycle management
- Logging, monitoring, and observability
- DevOps and DevSecOps practices
- Containerization and deployment strategies
- Next.js
- TypeScript
- Tailwind CSS
- Node.js
- Express.js
- PostgreSQL
- MongoDB (experiments)
- PayMongo Sandbox API
- Docker
- Docker Compose
- GitHub Actions
- Environment Variables
- Trivy
- CodeQL
- OWASP Security Practices
- Logging & Monitoring
- Repository setup
- Frontend initialization
- Backend initialization
- Docker
- Docker Compose
- PostgreSQL
- Redis
- Environment variables
- Health endpoints
- Logging
- Product catalog
- Checkout flow
- Create payment intent
- Payment success page
- Payment failure page
- Sandbox testing
- Controllers
- Services
- Repositories
- Middleware
- Validation
- Error handling
- API documentation
- Products
- Orders
- Customers
- Payment records
- Transaction history
- Receive webhooks
- Signature verification
- Event validation
- Payment confirmation
- Audit logging
- Retry handling
- Environment secrets
- API credential protection
- Input validation
- Helmet
- CORS
- Rate limiting
- Duplicate transaction prevention
- Secure error handling
- Principle of least privilege
- JWT Authentication
- Refresh tokens
- Role-Based Access Control
- Protected routes
- Admin dashboard
- Application logging
- Audit logs
- Metrics
- Prometheus
- Grafana
- Health checks
- Dashboard visualization
- GitHub Actions
- Automated testing
- Trivy scanning
- CodeQL
- Secure CI/CD
- Deployment pipeline
- Deployments
- Services
- ConfigMaps
- Secrets
- Persistent Volumes
- Ingress
- Scaling
- Rolling updates
- Backup strategies
- Disaster recovery
- Monitoring
- Alerting
- Incident response
- Scaling considerations
- Infrastructure best practices
Secured-Payment-Paymongo-Practice/
├── frontend/
├── backend/
├── docker/
├── monitoring/
├── kubernetes/
├── scripts/
├── .github/
│
└── docs/
├── api/
├── architecture/
├── checkpoints/
├── decisions/
├── diagrams/
├── experiments/
├── mental-models/
└── security/
This repository aims to answer questions such as:
- How do payment gateways communicate with applications?
- How are checkout sessions created and validated?
- Why are webhooks required for payment confirmation?
- How are webhook requests verified?
- How do applications prevent duplicate transactions?
- How should payment APIs be secured?
- How are sensitive credentials protected?
- How are payment systems monitored in production?
- How do DevOps and DevSecOps practices improve reliability and security?
- How are payment services deployed and operated using containers and Kubernetes?
This repository is designed as an engineering notebook.
Documentation includes:
- Architecture decisions
- Mental models
- Security notes
- Experiment logs
- Checkpoint reflections
- Infrastructure diagrams
- API documentation
Each checkpoint documents:
- The problem being explored
- Implementation details
- Challenges encountered
- Lessons learned
- Future improvements
This repository is not intended to become a production payment platform.
Instead, it serves as an engineering laboratory for exploring the technologies, security practices, infrastructure, and architectural decisions behind modern payment systems.
The objective is not simply to integrate a payment provider.
The objective is to understand why payment systems are designed the way they are and how secure engineering practices contribute to building reliable applications.
This repository is intended solely for educational purposes and uses the PayMongo Sandbox environment.
No real customer payments should ever be processed through this project.
Sensitive credentials, API keys, and secrets must never be committed to the repository.
Production payment systems require significantly more security, compliance, auditing, and operational controls than those demonstrated in this learning project.
This project is released under the MIT License.
It is provided for educational purposes and experimentation.