Finance Tracker API

A RESTful API for tracking personal income and expenses, built with ASP.NET Core 8, Entity Framework Core, and SQLite. Features JWT authentication, clean architecture (Controller → Service → Repository), and Swagger documentation.

Tech Stack

• Language: C# (.NET 8)
• Framework: ASP.NET Core Web API
• ORM: Entity Framework Core
• Database: SQLite
• Auth: JWT Bearer Tokens
• Docs: Swagger / Swashbuckle

Getting Started

Prerequisites

• .NET 8 SDK

Run the project

# Clone the repo
git clone https://github.com/Timothynyezi/FinanceTrackerAPI.git
cd FinanceTrackerAPI

# Update the JWT key in appsettings.json (see Configuration below)

# Install EF Core tools (first time only)
dotnet tool install --global dotnet-ef

# Apply migrations to create the SQLite database
# Note: if migrations already exist, skip the 'add' step and just run 'database update'
dotnet ef database update

# Run the API in Development mode (required for Swagger)
ASPNETCORE_ENVIRONMENT=Development dotnet run

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

Configuration

This project uses .NET User Secrets to keep the JWT signing key out of source control. After cloning, run dotnet user-secrets init followed by dotnet user-secrets set "Jwt:Key" "your-secure-random-key-min-32-chars". Generate a strong key with openssl rand -base64 32. appsettings.json intentionally ships with an empty Jwt:Key — User Secrets will override it automatically when running in Development mode. In production, set Jwt:Key as an environment variable instead, e.g. export Jwt__Key="your-production-key". Security Note An earlier commit contained a hardcoded JWT secret. This key has been rotated, removed from appsettings.json, and scrubbed from git history. The project now uses .NET User Secrets for local development and environment variables for production.

Testing with Swagger

1. Open http://localhost:5000/swagger
2. Register a user via POST /api/auth/register
3. Login via POST /api/auth/login and copy the token from the response
4. Click the Authorize button at the top right of the Swagger page
5. Enter Bearer {your_token} and click Authorize
6. All protected endpoints are now accessible

API Endpoints

Auth

Method	Endpoint	Description	Auth Required
POST	/api/auth/register	Register a new user	No
POST	/api/auth/login	Login and receive JWT token	No

Transactions

Method	Endpoint	Description	Auth Required
GET	/api/transactions	Get all transactions for logged-in user	Yes
GET	/api/transactions/{id}	Get a specific transaction	Yes
POST	/api/transactions	Create a new transaction	Yes
PUT	/api/transactions/{id}	Update a transaction	Yes
DELETE	/api/transactions/{id}	Delete a transaction	Yes

Categories

Method	Endpoint	Description	Auth Required
GET	/api/categories	Get all categories	Yes
POST	/api/categories	Create a new category	Yes

Example Requests

Register

POST /api/auth/register
{
  "username": "thami",
  "password": "securepassword123"
}

Login

POST /api/auth/login
{
  "username": "thami",
  "password": "securepassword123"
}

Create Transaction

POST /api/transactions
Authorization: Bearer {your_token}

{
  "description": "Monthly salary",
  "amount": 15000.00,
  "date": "2026-05-01T00:00:00",
  "type": 0,
  "categoryId": 1
}

Note: type — 0 = Income, 1 = Expense

Update Transaction (partial update supported)

PUT /api/transactions/1
Authorization: Bearer {your_token}

{
  "description": "Updated description",
  "amount": 18000.00
}

Architecture

Controllers/     → Handle HTTP requests and responses
Services/        → Business logic and DTO mapping
Repositories/    → Database access layer
Models/          → Entity classes (User, Transaction, Category)
DTOs/            → Request and response data shapes with validation
Data/            → EF Core DbContext and migrations
Middleware/      → Global error handling

Default Categories (seeded on first run)

Salary, Food & Groceries, Transport, Utilities, Entertainment, Healthcare, Other

Author

Thamsanqa Timothy Nyezi github.com/Timothynyezi | linkedin.com/in/tt-nyezi