Both FastAPI and Django are powerful Python web frameworks, but they have different design philosophies and are suited for different use cases. Here are some advantages of using FastAPI over Django for building APIs:

* Performance : FastAPI is designed to be high-performance, leveraging asynchronous programming to handle a large number of concurrent requests efficiently. This makes it well-suited for applications with high performance requirements. Django, while powerful, may have more overhead and is traditionally synchronous.

* Automatic API Documentation : FastAPI automatically generates interactive API documentation based on the Python type hints used in the code. This documentation is accessible through Swagger UI and ReDoc, providing developers with an easy way to understand and test the API. Django requires additional tools or manual documentation efforts.

* Type Hints and Validation : FastAPI uses Python type hints for request and response validation. This not only helps in catching errors early in the development process but also improves code readability. Django typically relies on serializers and forms for data validation.

* Asynchronous Support : FastAPI fully supports asynchronous programming, allowing you to write asynchronous routes and take advantage of the performance benefits of asynchronous I/O operations. Django supports asynchronous views as of version 3.1, but its core design is synchronous.

* Dependency Injection System : FastAPI has a built-in dependency injection system that makes it easy to manage and inject dependencies in a clean and organized way. Django, while having support for dependency injection, may not have it as seamlessly integrated as FastAPI.

* Minimal Boilerplate Code : FastAPI reduces the amount of boilerplate code required to build APIs, especially with automatic data validation and documentation. This can lead to faster development cycles and cleaner, more maintainable code.

* WebSocket Support : FastAPI has built-in support for handling WebSocket communication, enabling real-time bidirectional communication between clients and the server. Django channels provides WebSocket support for Django but may involve additional configuration and setup.

* Single-File Mode : FastAPI supports a "single-file" mode, allowing you to define routes directly in the main application file without the need for separate views, serializers, and other components. This can be convenient for small projects or quick prototyping.

* Simplicity and Explicitness : FastAPI is designed to be simple, explicit, and easy to use. It encourages the use of Python type hints and follows the principle of least surprise. Django, being a full-fledged web framework, may come with more features and abstractions, which could be overkill for API-focused projects.

* No ORM (Object-Relational Mapping) : FastAPI does not come with its own ORM. While Django's ORM is powerful and feature-rich, in certain scenarios, using an ORM may be unnecessary or overcomplicated for API-only projects. FastAPI allows developers to choose their preferred database tools.