MiniPay 💳

MiniPay is a lightweight digital wallet and payment management system built with Go. It provides secure user authentication, wallet management, balance deposits, peer-to-peer transfers, and transaction tracking through a RESTful API.

The project demonstrates modern backend development practices including JWT-based authentication, layered architecture, database persistence, and secure transaction handling.

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Features

User Authentication

• User registration
• User login
• Password hashing using BCrypt
• JWT token generation and validation
• Protected API routes

Wallet Management

• Create a personal wallet
• View wallet details
• Deposit funds into wallet
• Retrieve current wallet balance

Transactions

• Transfer money between wallets
• Transaction recording and storage
• View transaction history
• Balance validation before transfers

Security

• Password encryption with BCrypt
• JWT authentication middleware
• Protected routes
• Database-backed persistence

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Tech Stack

Backend

• Go (Golang)
• Gin Web Framework

Database

• MySQL
• GORM ORM

Authentication

• JWT (JSON Web Tokens)
• BCrypt Password Hashing

Frontend

• HTML
• JavaScript

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Project Architecture

minipay/
│
├── cmd/
│   └── main.go
│
├── config/
│   ├── config.go
│   ├── database.go
│   └── jwt.go
│
├── handlers/
│   ├── auth.go
│   ├── wallet.go
│   └── transaction.go
│
├── middleware/
│   └── auth.go
│
├── models/
│   ├── user.go
│   ├── wallet.go
│   └── transaction.go
│
├── repositories/
│   ├── wallet_repository.go
│   └── transaction_repository.go
│
├── services/
│   ├── auth_service.go
│   ├── wallet_service.go
│   └── transaction_service.go
│
├── ui/
│   └── index.html
│
├── go.mod
└── README.md

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System Design

MiniPay follows a layered architecture:

Handler Layer

Handles incoming HTTP requests and API responses.

Service Layer

Contains business logic such as:

• Wallet operations
• Money transfers
• Authentication workflows

Repository Layer

Responsible for database interactions.

Database Layer

Stores:

• Users
• Wallets
• Transactions

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Database Models

User

type User struct {
    Name     string
    Email    string
    Password string
}

Wallet

type Wallet struct {
    UserID  uint
    Balance float64
}

Transaction

type Transaction struct {
    SenderWalletID   uint
    ReceiverWalletID uint
    Amount           float64
    Status           string
}

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API Endpoints

Public Routes

Register User

POST /register

Request:

{
  "name": "John Doe",
  "email": "john@example.com",
  "password": "password123"
}

---

Login User

POST /login

Request:

{
  "email": "john@example.com",
  "password": "password123"
}

Response:

{
  "message": "Login successful",
  "token": "<jwt-token>"
}

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Protected Routes

All routes below require:

Authorization: Bearer <jwt-token>

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Get Current User

GET /me

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Create Wallet

POST /wallet/create

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Get Wallet Information

GET /wallet

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Deposit Funds

POST /wallet/deposit

Example:

{
  "amount": 1000
}

---

Transfer Funds

POST /transfer

Example:

{
  "receiver_wallet_id": 2,
  "amount": 250
}

---

Transaction History

GET /transactions

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Installation

Clone Repository

git clone https://github.com/SulakshanCGhimire/minipay.git
cd minipay

Install Dependencies

go mod tidy

Configure Environment Variables

Create a .env file:

DB_USER=root
DB_PASSWORD=password
DB_HOST=localhost
DB_PORT=3306
DB_NAME=minipay

JWT_SECRET=your_secret_key

Run MySQL

Ensure MySQL is running and the configured database exists.

Start Server

go run cmd/main.go

Server runs at:

http://localhost:8080

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Testing the API

Health Check

GET /ping

Response:

{
  "message": "pong"
}

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Future Improvements

• Transaction reversal support
• Account verification
• Admin dashboard
• Real-time notifications
• Mobile application
• QR-based payments
• Multi-currency wallets
• Payment gateway integration
• Fraud detection module
• Transaction analytics dashboard

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Learning Outcomes

This project demonstrates:

• REST API Development
• Backend Engineering
• JWT Authentication
• Password Security
• Database Design
• Layered Architecture
• Repository Pattern
• Financial Transaction Processing

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Author

Sulakshan Chandra Ghimire

Computer Engineering Student

GitHub: https://github.com/SulakshanCGhimire

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License

This project is licensed under the MIT License.