uvicorn

The lightning-fast ASGI server.

uvicorn Permissive license BSD-3-Clause Active v0.52.3 released 2026-08-13

Install

uvicorn on PyPI

pip

pip install uvicorn

uv

uv add uvicorn

poetry

poetry add uvicorn

Package facts

License	BSD-3-Clause (permissive)
Python support	supports the current Python release (>=3.10)
Install friction	low — pure-Python wheel
Runtime dependencies	3 — click, h11, typing-extensions
Maintenance	actively maintained — 0 days since the last release
First released	2017-06-05
Popularity	one of the 100 most-downloaded packages on PyPI (30-day window, as of 2026-08-13)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-13)

Evidence: uvicorn-0.52.3-py3-none-any.whl

Development Status :: 4 - BetaEnvironment :: Web EnvironmentIntended Audience :: DevelopersOperating System :: OS IndependentProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: Internet :: WWW/HTTP

About uvicorn

from the package's own PyPI description — quoted content, verbatim

An ASGI web server, for Python.

Build Status (image) Package version (image) Supported Python Version (image) Discord (image)

Documentation: https://uvicorn.dev

Source Code: https://www.github.com/Kludex/uvicorn

Uvicorn is an ASGI web server implementation for Python.

Until recently Python has lacked a minimal low-level server/application interface for async frameworks. The [ASGI specification][asgi] fills this gap, and means we're now able to start building a common set of tooling usable...

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AI interpretation — verify before relying

AI-generated interpretation of the package facts above; every digit, version, license, or vulnerability id it cites is grounded in the facts already shown on this page

Uvicorn is a lightning-fast ASGI web server for Python that runs async web applications with support for HTTP/1.1 and WebSockets.

Low install friction with only three pure-Python runtime dependencies (click, h11, typing-extensions). Actively maintained with a recent release. Optional extras like uvloop and httptools are available for performance tuning.

BSD-3-Clause permissive license allows commercial and private use with minimal restrictions, requiring only license and copyright notice preservation.

Usage

pip install uvicorn

# example.py
async def app(scope, receive, send):
    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [(b'content-type', b'text/plain')],
    })
    await send({
        'type': 'http.response.body',
        'body': b'Hello, world!',
    })

# Run: uvicorn example:app

Requires Python 3.10 or later; application must be an ASGI-compliant async callable.

Verdict: Uvicorn is a top-100 PyPI package with active maintenance, permissive licensing, and minimal dependencies. No known vulnerabilities and low install friction make it a reliable choice for running ASGI applications in production or development.

Needs verification

Whether the repository at github.com/sponsors/encode is the canonical source or if github.com/Kludex/uvicorn is an alternative fork.
Performance characteristics and real-world throughput compared to alternative ASGI servers mentioned in the documentation.

asgi web server pythonasync http serverwebsocket server pythonpython asgi implementationfast async web frameworkhttp/1.1 serveruvicorn asgi