Fintech Wallet API

A backend API for a fintech wallet system built with ASP.NET Core and Entity Framework Core. The system allows users to register, create wallets, deposit and withdraw funds, transfer money, and fund wallets via Paystack payment gateway.

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🚀 Features

• User registration and login with secure password hashing
• JWT-based authentication
• Create and manage digital wallets
• Deposit and withdraw funds
• Transfer money between wallets
• Fund wallets via Paystack payment gateway
• Payment verification with automatic wallet crediting
• Transaction history
• Generic repository pattern
• RESTful API design with Swagger documentation
• Unit tests with xUnit and Moq

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🧰 Tech Stack

Layer	Technology
Framework	ASP.NET Core (.NET 10)
Language	C#
Database	SQLite (via Entity Framework Core)
Authentication	JWT (JSON Web Token)
Payment	Paystack
Testing	xUnit, Moq
Documentation	Swagger / Swashbuckle

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🏗 Architecture

The project follows a layered architecture with a factory pattern for payment processing.

Controller → Service → Repository → Database
                 ↘
            PaymentFac → IPayment (Paystack)

• Controllers — handle HTTP requests and responses
• Services — contain business logic
• Repositories — generic data access via IRepository<T>
• Payments — payment gateway integration using factory pattern
• Models — domain entities and DTOs

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📂 Project Structure

FintechWallet/
│
├── Controllers/
│   ├── AuthController.cs          # Registration & login endpoints
│   └── WalletController.cs        # Wallet, transaction & payment endpoints
│
├── Services/
│   ├── IAuthService.cs            # Auth service interface
│   ├── AuthService.cs             # JWT token generation, password hashing
│   ├── IWalletService.cs          # Wallet service interface
│   └── WalletService.cs           # Deposit, withdraw, transfer logic
│
├── Repositories/
│   ├── IRepository.cs             # Generic repository interface
│   └── Repository.cs              # Generic repository implementation
│
├── Payments/
│   ├── IPayment.cs                # Payment provider interface
│   ├── PaymentFac.cs              # Payment factory
│   └── Paystack/
│       └── PaystackPayment.cs     # Paystack payment implementation
│
├── Models/
│   ├── User.cs                    # User entity
│   ├── Wallet.cs                  # Wallet entity
│   ├── Transaction.cs             # Transaction entity & enum
│   ├── Payment.cs                 # Payment request model
│   ├── PaymentLog.cs              # Payment audit log entity
│   └── Dtos.cs                    # Data transfer objects
│
├── Data/
│   └── WalletDbContext.cs         # EF Core database context
│
├── Tests/
│   └── WalletServiceTests.cs      # Unit tests for WalletService
│
├── Program.cs                     # App configuration & DI setup
├── appsettings.json               # App settings & connection strings
└── README.md

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⚙️ Getting Started

Prerequisites

• .NET SDK 10 or later
• Visual Studio, VS Code, or Rider

Installation

# Clone the repository
git clone https://github.com/muisoft/fintech-wallet-dotnet.git

# Navigate to the project folder
cd fintech-wallet-dotnet

# Restore dependencies
dotnet restore

# Run the application
dotnet run

The API will be available at http://localhost:5000 with Swagger UI at /swagger.

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📘 API Endpoints

Auth

Method	Endpoint	Description
POST	/api/auth/register	Register a new user
POST	/api/auth/login	Login and receive JWT token

Wallets

Method	Endpoint	Description
POST	/api/wallets	Create a new wallet
GET	/api/wallets	List all user wallets
GET	/api/wallets/{id}	Get wallet details
POST	/api/wallets/{id}/deposit	Deposit funds
POST	/api/wallets/withdraw	Withdraw funds
POST	/api/wallets/transfer	Transfer between wallets
GET	/api/wallets/{id}/transactions	Get transaction history

Payments

Method	Endpoint	Description
POST	/api/wallets/fund-with-payment	Initialize Paystack payment
POST	/api/wallets/verify-funding	Verify payment & credit wallet

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🔐 Authentication

The API uses JWT Bearer authentication. Include the token in the Authorization header:

Authorization: Bearer <your_token>

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🧪 Running Tests

dotnet test

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📄 License

This project is licensed under the MIT License.

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👤 Author

Muideen Adewale — Senior Software Engineer