Explore the differences between RESTful API design and FastAPI, a powerful Python framework for building APIs. Learn which to use for your next backend project.
June 4, 2025
|
6 min read
APIs are essential to modern software development, and choosing the right approach can impact everything from development speed to system performance. Two common paths in the Python ecosystem are RESTful API design and using FastAPI, a modern web framework.
In this post, we'll explore what each one means, how they differ, and when to use each.
A RESTful API is an API that follows the architectural principles of REST (Representational State Transfer). It's not a specific tool or library, but a way of designing web services to be stateless, resource-based, and rely on standard HTTP methods.
Core REST Principles:
GET
, POST
, PUT
, DELETE
/users/123
)Example (Conceptual REST):
You can implement RESTful APIs using frameworks like Flask, Django REST Framework, or Express.js (for JavaScript).
FastAPI is a modern, fast (high-performance) web framework for building APIs with Python 3.7+ based on standard Python type hints. It is designed to be easy to use, highly performant, and developer-friendly.
Why FastAPI stands out:
async
/await
)Example (FastAPI code):
When you visit /docs
, FastAPI gives you interactive API documentation automatically.
Feature | RESTful API (Design) | FastAPI (Framework) |
---|---|---|
Type | Architectural style | Python web framework |
Language-Specific | No | Yes (Python only) |
Performance | Depends on implementation | Very high (async-based) |
Data Validation | Manual or library-specific | Automatic with Pydantic |
API Documentation | Manual or external tools | Auto-generated (Swagger, ReDoc) |
Learning Curve | Low to medium | Moderate (Python typing) |
Best Use Case | Any backend architecture | Python-based modern APIs |
Use RESTful API (Design) if:
Use FastAPI if:
While RESTful APIs and FastAPI are often compared, they serve different purposes. RESTful API is a design paradigm, whereas FastAPI is a concrete implementation built for speed and developer efficiency.
If you're using Python and want a clean, performant, and scalable way to build APIs, FastAPI is one of the best choices available today. If you're designing APIs at a higher level or across multiple platforms, RESTful architecture provides a solid foundation.
Let your use case-and your stack-guide your decision.