FastAPI Backend Development Guidelines

Purpose

Comprehensive guide for modern FastAPI development with async Python, emphasizing Domain-Driven Design, layered architecture (Router → Service → Repository), SQLModel ORM, and async best practices.

When to Use This Skill

• Creating new API routes or endpoints
• Building domain services and business logic
• Implementing repositories for data access
• Setting up database models with SQLModel
• Async/await patterns and error handling
• Organizing backend code with DDD
• Pydantic validation and DTOs
• Python async best practices