Expense tracking API with FastAPI

A documented REST API for expenses and budgets with auth, pagination and reports.

Why build it

Shows you can design an API properly: validation, auth, pagination, migrations and tests, not just return JSON.

Features

• JWT auth
• CRUD for expenses and categories
• Monthly budget with alerts
• Pagination and filtering
• Report endpoint grouped by category

Roadmap

1. p1

   Foundations

   • FastAPI project layout
   • SQLAlchemy models and Alembic migrations
   • Pydantic schemas
2. p2

   Auth

   • Password hashing with argon2
   • JWT access tokens
   • Per-user data isolation tests
3. p3

   Features

   • Expense CRUD with filters
   • Cursor pagination
   • Report queries with GROUP BY
4. p4

   Production

   • pytest with a test database
   • Dockerfile
   • CI in GitHub Actions
   • Deploy

Common pitfalls

• Forgetting to scope every query to the current user
• Offset pagination that gets slow and inconsistent on big tables

Skills you will practise

• REST design
• ORM and migrations
• Auth
• CI