DabDub - Universal Crypto-to-Fiat Settlement Infrastructure Built on Stellar

Seamless crypto payments, instant fiat settlements - A multi-chain settlement infrastructure that bridges Web3 payments with traditional banking, enabling merchants to accept stablecoin payments and receive instant fiat settlements.

Overview

DabDub is a B2B2C payment settlement platform that enables businesses to accept cryptocurrency payments (USDC) from customers while receiving instant fiat settlements in their bank accounts. Built with multi-chain support across EVM and non-EVM networks, it abstracts away blockchain complexity for merchants while providing secure, compliant, and fast payment processing.

Key Value Propositions

• Zero Crypto Knowledge Required: Merchants receive fiat, customers pay crypto
• Multi-Chain Support: Works across 7+ blockchain networks
• Instant Settlement: Automated crypto-to-fiat conversion and bank transfers
• QR Code Payments: Simple scan-and-pay experience
• Enterprise-Grade: Built for scale with monitoring, webhooks, and APIs
• Progressive Web App: Works offline, installable on any device

🏗️ Architecture

Technology Stack

Backend (Settlement API)

• Framework: NestJS (TypeScript)
• Database: PostgreSQL with TypeORM
• Blockchain Integration: ethers.js, Stellar SDK, Starknet.js, Stacks.js
• Payment Processing: Automated monitoring and settlement
• API Design: RESTful with webhook support
• Job Scheduling: Cron-based blockchain monitoring

Frontend (Merchant & Customer Portal)

• Framework: Next.js 14 (App Router)
• Type Safety: TypeScript
• Styling: Tailwind CSS
• PWA Support: Offline-first architecture
• State Management: React Context / Zustand
• Web3 Integration: wagmi, viem, RainbowKit
• QR Generation: qrcode.react

Supported Blockchain Networks

EVM-Compatible Chains

1. Polygon (Layer 2 Ethereum)

   • Gas: Ultra-low (~$0.01)
   • Speed: ~2 seconds
   • Best for: High-volume transactions

2. Base (Coinbase L2)

   • Gas: Low (~$0.02)
   • Speed: ~2 seconds
   • Best for: Coinbase ecosystem integration

3. Celo (Mobile-first EVM)

   • Gas: Ultra-low (~$0.001)
   • Speed: ~5 seconds
   • Best for: Mobile payments, emerging markets

4. Arbitrum (Optimistic Rollup)

   • Gas: Low (~$0.02)
   • Speed: ~1 second
   • Best for: DeFi integrations

5. Optimism (Optimistic Rollup)

   • Gas: Low (~$0.02)
   • Speed: ~2 seconds
   • Best for: Ethereum ecosystem

Non-EVM Chains

6. Starknet (ZK-Rollup)

   • Gas: Very low
   • Speed: ~10 seconds
   • Best for: High-security applications

7. Stellar (Fast & Low-Cost)

   • Gas: Minimal (~$0.0001)
   • Speed: ~5 seconds
   • Best for: Cross-border payments, remittances

8. Stacks (Bitcoin Layer 2)

   • Gas: Moderate
   • Speed: Bitcoin block time
   • Best for: Bitcoin-secured settlements

🚀 Features

Core Functionality

1. Payment Request Generation

• Generate unique payment requests with QR codes
• Multi-chain support with automatic network selection
• Customizable expiration times
• Real-time exchange rate conversion
• Merchant metadata attachment

2. Blockchain Monitoring

• Automated deposit detection across all supported chains
• Block-by-block transaction scanning
• Intelligent payment matching algorithms
• Confirmation tracking (12+ confirmations for security)
• Failed transaction handling and retry logic

3. Settlement Automation

• Automatic fiat conversion via partner liquidity providers
• Bank transfer execution
• Multi-currency support (USD, NGN, EUR, GBP, etc.)
• Batch settlement optimization
• Settlement status tracking

4. Merchant Dashboard

• Real-time payment tracking
• Transaction history and analytics
• Settlement reports and exports
• API key management
• Webhook configuration
• Multi-user access control

5. Developer Tools

• RESTful API with comprehensive documentation
• Webhook system for real-time notifications
• SDK support (JavaScript/TypeScript, Python, Go)
• Sandbox environment for testing
• Postman collection and OpenAPI specs
• Swagger documentation for API docs

Advanced Features

Security

• Multi-signature wallet support
• Rate limiting and DDoS protection
• API key authentication with scopes
• Encrypted data storage
• Audit logging for compliance
• PCI-DSS compliance ready

Monitoring & Observability

• Prometheus metrics export
• Grafana dashboard templates
• Sentry error tracking
• Transaction tracing
• Performance monitoring
• Uptime monitoring with alerting

Scalability

• Horizontal scaling support
• Database connection pooling
• Redis caching for hot data
• Message queue for async processing
• Load balancing ready
• CDN integration for static assets

🛠️ Installation & Setup

Prerequisites

• Node.js 18+ and npm/yarn/pnpm
• PostgreSQL 14+
• Redis 6+ (optional, for caching)
• Docker & Docker Compose (recommended)

Quick Start with Docker

# Clone the repository
git clone https://github.com/yourusername/cryptosettle.git
cd cryptosettle

# Copy environment variables
cp .env.example .env

# Edit .env with your configurations
nano .env

# Start all services with Docker Compose
docker-compose up -d

# Backend will be available at http://localhost:3000
# Frontend will be available at http://localhost:3001

Manual Setup

Backend Setup

cd backend

# Install dependencies
npm install

# Set up environment variables
cp .env.example .env
# Edit .env with your configurations

# Run database migrations
npm run migration:run

# Start development server
npm run start:dev

# Run tests
npm run test
npm run test:e2e

Frontend Setup

cd frontend

# Install dependencies
npm install

# Set up environment variables
cp .env.local.example .env.local
# Edit .env.local with your configurations

# Start development server
npm run dev

# Build for production
npm run build

# Start production server
npm run start

Environment Variables

Backend (.env)

# Server Configuration
PORT=3000
NODE_ENV=development

# Database
DB_HOST=localhost
DB_PORT=5432
DB_USER=postgres
DB_PASSWORD=your_secure_password
DB_NAME=cryptosettle

# Redis (Optional)
REDIS_HOST=localhost
REDIS_PORT=6379

# Blockchain Wallets
DEPOSIT_WALLET_ADDRESS=0xYourDepositWalletAddress
TREASURY_WALLET_PRIVATE_KEY=0xYourTreasuryPrivateKey

# EVM RPC Endpoints
POLYGON_RPC_URL=https://polygon-mainnet.g.alchemy.com/v2/YOUR_KEY
BASE_RPC_URL=https://base-mainnet.g.alchemy.com/v2/YOUR_KEY
CELO_RPC_URL=https://forno.celo.org
ARBITRUM_RPC_URL=https://arb-mainnet.g.alchemy.com/v2/YOUR_KEY
OPTIMISM_RPC_URL=https://opt-mainnet.g.alchemy.com/v2/YOUR_KEY

# Non-EVM Networks
STELLAR_NETWORK=PUBLIC # or TESTNET
STELLAR_ACCOUNT_SECRET=SXXX...
STARKNET_RPC_URL=https://starknet-mainnet.public.blastapi.io
STARKNET_PRIVATE_KEY=0x...
STACKS_RPC_URL=https://stacks-node-api.mainnet.stacks.co
STACKS_PRIVATE_KEY=...

# Partner API (Fiat Liquidity Provider)
PARTNER_API_URL=https://partner-api.com/v1
PARTNER_API_KEY=your_partner_api_key

# Security
JWT_SECRET=your_jwt_secret_key_min_32_chars
API_KEY_SALT=your_api_key_salt

# Monitoring
SENTRY_DSN=https://[email protected]/xxx

Frontend (.env.local)

NEXT_PUBLIC_API_URL=http://localhost:3000/api/v1
NEXT_PUBLIC_WS_URL=ws://localhost:3000

# Blockchain Network IDs
NEXT_PUBLIC_POLYGON_CHAIN_ID=137
NEXT_PUBLIC_BASE_CHAIN_ID=8453
NEXT_PUBLIC_CELO_CHAIN_ID=42220

# WalletConnect Project ID
NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID=your_project_id

# Analytics (Optional)
NEXT_PUBLIC_GA_TRACKING_ID=G-XXXXXXXXXX

Webhook Events

DabDub sends webhooks for the following events:

• payment.created - New payment request created
• payment.confirmed - Payment confirmed on blockchain
• payment.settling - Fiat settlement in progress
• payment.settled - Merchant received fiat
• payment.failed - Payment or settlement failed
• payment.expired - Payment request expired

🌐 Blockchain Integration Details

EVM Networks (Polygon, Base, Celo, Arbitrum, Optimism)

Token Standard: ERC-20 (USDC)

🎨 Frontend Features

Progressive Web App (PWA)

• Offline Support: Works without internet connection
• Installable: Add to home screen on mobile devices
• Push Notifications: Real-time payment updates
• Background Sync: Queue transactions when offline

Merchant Dashboard

• Overview: Real-time metrics and charts
• Payments: List, filter, and search all payments
• Settlements: Track fiat settlements
• Analytics: Revenue trends, conversion rates
• Settings: API keys, webhooks, profile

Customer Payment Flow

1. Scan QR code with any Web3 wallet
2. Auto-populate payment details
3. Confirm transaction
4. Real-time status updates
5. Receipt generation

Cloud Platforms

Railway

railway up

Vercel (Frontend)

vercel --prod

Project Links

• Website: https://dabdub.xyz
• Documentation: https://docs.dabdub.xyz
• API Reference: https://api.dabdub.xyz/docs
• Status Page: https://status.dabdub.xyz

Community

• Twitter: @CryptoSettle
• Telegram: CryptoSettle Community

📞 Support

• Email: [email protected]
• Enterprise Inquiries: [email protected]

Built with ❤️ by the DabDub team