SafTap

Bridging Global Liquidity to Local Commerce. The frictionless bridge for tourists to pay Kenyan merchants via USDC-to-M-PESA.

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The Vision

SafTap is a real-time payment settlement engine designed for the Kenyan tourism ecosystem. We solve the "Last Mile" friction of international payments by allowing tourists to pay in digital dollars (USDC) while merchants receive instant settlement in Kenyan Shillings (KES) via M-PESA.

The goal: Make the blockchain invisible. No wallet setups, no seed phrases, and no crypto knowledge required for the user.

The Problem

1. High FX Fees: Tourists lose 3-7% on foreign exchange bureaus or predatory bank card rates.
2. Settlement Delays: Merchants often wait days for international credit card settlements.
3. Hardware Barriers: Small-scale merchants (curio shops, local guides) cannot afford expensive POS terminals.
4. Cash Risks: Tourists carrying large amounts of cash are targets for theft.

The Solution

SafTap acts as a Liquidity Bridge:

• Tourist Side: A "Scan-to-Pay" web interface that handles USDC transfers behind the scenes.
• Middle Layer: A blockchain monitor that detects on-chain transactions and triggers instant liquidity release.
• Merchant Side: Receives standard M-PESA KES directly to their phone, exactly like a local transaction.

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How It Works

1. Invoice Generation: The merchant enters the KES amount in the SafTap Mobile App.
2. QR Trigger: The app generates a dynamic QR code containing the KES-to-USDC conversion (via real-time Oracles).
3. Payment: The tourist scans and authorizes a USDC transfer (Stablecoin).
4. Settlement: The SafTap backend detects the on-chain success and instantly triggers an M-PESA B2C/C2B payout to the merchant's till.

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Technical Architecture

Apps & Packages

• frontend: SoftPOS Interface. A React Native (Expo) app for merchants to manage sales and generate payment QRs.
• apps/backend: The Settlement Engine. A Node.js/TypeScript service that monitors the blockchain and integrates with the M-PESA Daraja API.
• packages/shared: The Core Logic. Shared types, constants, and utility functions for cross-platform consistency.

Blockchain Layer

• Currency: USDC (Stable, Liquid, Global).
• Network: Ethereum L2 (Polygon/Base/Celo) for sub-cent transaction fees.
• Monitoring: Real-time event listeners watching the "Liquidity Vault" for incoming tourist funds.

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Tech Stack

Layer	Technology
Frontend	React Native, Expo, TypeScript
Backend	Node.js, Express, ethers.js
Blockchain	Solidity, USDC, L2 Networks
Payments	Safaricom M-PESA Daraja API
Monorepo	Turborepo, pnpm

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Installation & Setup

1. Clone the repository:

   git clone https://github.com/your-repo/saftap.git
   cd saftap

2. Install dependencies:

   pnpm install

3. Configure Environment: Create .env files in apps/backend and frontend based on the provided .env.example.

4. Run the project:

   # Start all services
   pnpm dev

Railway Deployment

Deploy the backend and frontend as separate Railway services connected to this repository.

Frontend service

1. Create a new Railway service from this repository.

2. Keep the service root directory set to / so pnpm can resolve the shared workspace package.

3. In Settings > Config-as-code, set the Railway Config File path to /frontend/railway.json.

4. Add API_BASE_URL as a service variable, including the backend /api path:

   API_BASE_URL=https://your-backend-domain.up.railway.app/api
   

5. Generate a public domain for the frontend service and deploy it.

The frontend config builds the Expo web export and serves frontend/dist on Railway's assigned PORT. In the deployment build plan, verify that the build command includes expo export --platform web and the start command is pnpm --filter @saftap/mobile start.

Backend service

Keep the backend service root directory set to / and set its Railway Config File path to /apps/backend/railway.json. The backend config builds only the shared package and backend, runs Prisma migrations before deployment, and checks /health before routing traffic.

Both services use Railpack and scoped workspace commands so frontend and backend deployments remain independent.

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Hackathon Context

This project was built for the Zone01 Kisumu On-Chain Hackathon (May 2026) at LakeBasin Mall.

• Track: DeFi & Finance
• Focus: Financial Inclusion & Regional Tourism Impact.

The Team

• Team SafTap - Full-stack Development & Blockchain Architecture

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License

This project is licensed under the MIT License - see the LICENSE file for details.

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Built with pride in Kisumu for the Global Traveler.