Starlette

Starlette is a lightweight, asynchronous web framework for Python built on top of the ASGI specification. It provides the core building blocks for creating web applications and APIs, with a focus on performance and flexibility. Starlette is designed to be the foundation for higher-level frameworks and services while remaining useful as a standalone toolkit.

Key features include an ASGI-compatible routing layer, request and response objects, middleware support, background tasks, and startup and shutdown events. It also provides WebSocket support, built-in support for serving static files, and utilities for handling cookies and sessions. The framework favors a minimal core with optional components that can be added as needed.

Starlette is asynchronous by design and runs on any ASGI server such as Uvicorn, Daphne, or Hypercorn. Its API emphasizes explicit, testable behavior and seamless interoperability with other Python libraries, including templating engines like Jinja2 and data validation tools when used in conjunction with larger stacks.

Historically, Starlette was created by Tom Christie and released as an open-source project to provide a fast, flexible ASGI toolkit. It serves as the underlying foundation for FastAPI, a popular high-performance API framework that combines Starlette with Pydantic for data validation and serialization. Starlette remains actively maintained by an open-source community and is distributed under the MIT license.