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Introduction
Starlette is a modern, high-performance asynchronous web framework for Python that serves as the foundation for the popular FastAPI. Built specifically for ASGI (Asynchronous Server Gateway Interface), Starlette gives developers powerful tools for creating fast and scalable web applications. In this article, we'll dive deep into every aspect of working with this framework, exploring its features and advantages.
What is Starlette
Project History and Goals
Starlette was created by Tom Christie, the renowned developer behind Django REST Framework. The project launched in 2018 with the goal of providing developers with a lightweight yet powerful tool for building asynchronous web applications in Python. Starlette's core philosophy is to deliver a minimalistic but functional framework that doesn't force specific solutions on developers.
Key Framework Features
Starlette stands out with several key features that make it attractive for modern web development:
- Full ASGI Support — ensures maximum compatibility with modern async servers
- Native Asynchronicity — all framework components are designed with async/await syntax
- Minimalist Architecture — provides only essential components without feature bloat
- High Performance — delivers excellent request processing speeds
- Modularity — lets you use only the components you need
- Easy Testing — includes built-in tools for writing tests
How Starlette Relates to FastAPI
FastAPI Architecture: Using Starlette as a Foundation
FastAPI is built on top of Starlette, using it as the base layer for handling HTTP requests, routing, and middleware. This allows FastAPI to focus on delivering additional features like automatic data validation, OpenAPI documentation generation, and Pydantic integration, while retaining all of Starlette's performance and flexibility.
Why FastAPI Chose Starlette as Its Base
Several factors drove the decision to use Starlette as FastAPI's foundation:
- Performance — Starlette delivers outstanding results in performance benchmarks
- ASGI Compatibility — full support for the modern async web application standard
- Architectural Stability — a well-designed and thoroughly tested codebase
- Active Community — regular updates and strong developer support
Benefits of Asynchronicity and Performance
ASGI Support and Async Calls
ASGI (Asynchronous Server Gateway Interface) is the new standard replacing WSGI for asynchronous applications. Starlette is fully ASGI-compatible, enabling you to:
- Handle thousands of concurrent connections
- Work efficiently with WebSocket connections
- Use modern async servers like Uvicorn and Hypercorn
- Integrate with async databases and external APIs
Performance Comparison with WSGI Frameworks
Unlike traditional WSGI frameworks (Flask, Django), Starlette delivers:
- Non-blocking I/O — requests don't block each other
- High Throughput — handles more requests per second
- Efficient Resource Usage — lower memory consumption
