Seamless Pay App

Seamless Pay is a next-generation C2C and B2C mobile payment platform that enables users to send, receive, and manage payments using PYUSD (PayPal USD).

It bridges traditional financial interactions with Web3 technology, offering a secure, intuitive, and modern way to transact between individuals and businesses. Users can manage balances, make purchases, and interact with merchants—all powered by blockchain smart contracts for transparency and traceability.

The platform includes:

🌐 A Next.js landing page for onboarding and marketing.

📱 A React Native mobile app as the main wallet and payment hub.

⚙️ An Express.js (TypeScript) API serving as the backend orchestrator, following SOLID principles and class-based architecture.

🧠 Smart Contracts built with Hardhat, ensuring secure on-chain payments and identity verification.

🪩 A PostgreSQL database managed via Drizzle ORM to store off-chain metadata (users, orders, KYC).

🔗 WalletConnect, ethers.js, and wagmi integrated across the app ecosystem to handle wallet sessions and contract calls seamlessly.

🪙🔗Smart Contracts (Hardhat + Ethers):

• Implements payment channels for PYUSD transfers.
• Manages escrow logic and C2C settlement rules.
• Uses ethers for deployment and testing, with wagmi hooks for frontend interaction.

⚙️Backend (Express + TypeScript):

• Built using class-based controllers following SOLID principles (single responsibility, dependency inversion, etc.).
• Integrates Zod for schema validation, zod-to-openapi for docs, and Scalar for API reference visualization.
• Connects to Drizzle ORM for transactional persistence.
• Handles authentication, KYB/KYC flows, and order reconciliation.

📱🧭Frontend (Next.js + React Native):

• Next.js landing page: introduces the product, guides users to the app, and includes wallet connect preview via wagmi.
• React Native app: main wallet and payment interface; integrates with WalletConnect and supports multi-chain in future releases.

🗃️Database (Drizzle + PostgreSQL):

• Manages off-chain data such as users, merchant profiles, and transaction logs.
• Uses migrations and seed scripts aligned with the API domain model.

📘Documentation (Scalar + Zod):

• API routes automatically documented via Zod schemas → OpenAPI → Scalar web docs.