# Technology Stack

# Technical Stack Recommendations

## 1. Architecture Overview

### Principles
1. **Microservices Architecture** - Modular, independently deployable
2. **Cloud-Native Design** - Containerized, elastic scaling
3. **Security by Design** - Zero-trust, encryption everywhere

## 2. Backend Technology

### Primary: Java/Spring Boot
- Built-in Spring Security, OAuth2
- ACID compliance for transactions
- Proven in regulated industries
- Spring Boot 3.x, Spring Cloud

### Secondary: Node.js
- WebSocket connections
- Push notifications
- Real-time updates

### Hybrid Approach
- **Java**: Auth, Accounts, Payments, Cards, Ledger, KYC/AML
- **Node.js**: WebSocket, Notifications, Real-time
- **Python**: Fraud ML, Risk Scoring, Analytics

## 3. Mobile Development

### Recommendation: Flutter

| Criteria | Flutter | React Native | Native |
|----------|---------|--------------|--------|
| Performance | Near-native | Good | Best |
| Code Sharing | 95%+ | 85-90% | 0% |
| Market Share | 46% | 35% | - |

**Why Flutter:**
- Same UI across iOS/Android
- Single codebase
- No JS bridge
- Used by major banks

**Stack:** Bloc, GoRouter, Dio, Hive, local_auth

## 4. Database & Storage

- **Primary**: PostgreSQL 16
- **Cache**: Redis 7
- **Queue**: Kafka/RabbitMQ
- **Documents**: S3
- **Search**: Elasticsearch

## 5. Infrastructure

### Cloud: AWS or GCP

**Components:**
- Kubernetes (EKS/GKE)
- Terraform
- GitHub Actions + ArgoCD
- Prometheus + Grafana
- CloudFlare (WAF)

## 6. Security

### OWASP MASVS
- AES-256, TLS 1.3
- Biometric auth, 2FA
- Certificate pinning
- Code obfuscation

## 7. MVP Stack

- **Backend**: Java 21 + Spring Boot 3.2, Node.js 20
- **Mobile**: Flutter 3.x
- **Data**: PostgreSQL, Redis, Kafka
- **Infra**: AWS/GCP, K8s, Terraform
- **Third-Party**: Swan (BaaS), Stripe Issuing, Sumsub (KYC)