System architecture

Veilpay is a TypeScript monorepo with mobile, backend, indexer, shared, contract, circuit, and native modules.

Repository layout

apps/
  consumer-app/      Expo React Native wallet
  backend/           Express API server
  indexer/           Chain indexing service

packages/
  shared/            Shared chain metadata and utilities
  circuits/          ZK circuit assets and experiments
  contracts-evm/     EVM contracts
  contracts-solana/  Solana programs
  spp-native/        Rust native module for Stellar SPP

Runtime layout

User device
  └─ Consumer app
       ├─ Secure wallet storage
       ├─ Chain signers
       ├─ Balance and transaction views
       └─ Privacy UX

Backend
  ├─ Express routes
  ├─ Prisma database access
  ├─ Redis coordination
  ├─ BullMQ queues
  ├─ RPC proxy
  └─ Chain indexer

Networks and services
  ├─ EVM RPC providers
  ├─ Solana RPC
  ├─ Stellar Horizon / Soroban
  ├─ Fiat ramp providers
  ├─ Sentry
  └─ Doppler

Data stores

• PostgreSQL stores backend relational data through Prisma.
• Redis supports sessions, queues, rate-limit state, and worker coordination.
• SecureStore stores sensitive mobile wallet material.
• Async/local app storage is used for non-secret app state where appropriate.

Operational pattern

The backend exposes an API surface, queues asynchronous work, and keeps sensitive infrastructure credentials out of the mobile binary. The consumer app owns user confirmation and signing.