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Quart is an async Python web framework that reimplements the Flask API using async/await syntax.
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It's designed to be compatible with Flask's API, making it relatively easy to migrate Flask applications to async patterns. It's built on top of ASGI (Asynchronous Server Gateway Interface) rather than WSGI.
Performance with async operations: Quart excels when your application needs to handle many concurrent I/O-bound operations - like multiple database queries, API calls, or WebSocket connections. The async approach allows better resource utilization than Flask's synchronous model.
Flask familiarity: If you know Flask, you already know most of Quart. The API is intentionally similar, so routes, blueprints, and most patterns feel familiar. This drastically reduces the learning curve.
Modern features: Built-in support for WebSockets, HTTP/2, and Server-Sent Events (SSE) without additional extensions.
Gradual migration path: You can migrate Flask apps incrementally since Quart maintains API compatibility.
FastAPI: Currently the most popular async Python framework. It's built on Starlette and Pydantic, offering automatic API documentation, request validation, and excellent performance. More opinionated than Quart.
Starlette: A lightweight ASGI framework that FastAPI is built on. More minimal and flexible, but requires more setup.
Sanic: Another async framework with a Flask-like API, known for speed. Less Flask-compatible than Quart.
AIOHttp: Comprehensive async framework with both client and server components. More complex, different API paradigm.
Litestar (formerly Starlite): Modern ASGI framework with OpenAPI support, similar philosophy to FastAPI but different design choices.
Ecosystem maturity: Quart's ecosystem is smaller than Flask's. While many Flask extensions have Quart equivalents, not everything is available.