---
id: h11
version: "0.16.0"
license: MIT
license_treatment: permissive
maintenance: aging
---

# h11 — A pure-Python, bring-your-own-I/O implementation of HTTP/1.1

License: permissive · Maintenance: aging · Popularity: top 100 on PyPI

## Install

pip install h11
uv add h11
poetry add h11

## Description

h11
===

.. image:: https://travis-ci.org/python-hyper/h11.svg?branch=master
   :target: https://travis-ci.org/python-hyper/h11
   :alt: Automated test status

.. image:: https://codecov.io/gh/python-hyper/h11/branch/master/graph/badge.svg
   :target: https://codecov.io/gh/python-hyper/h11
   :alt: Test coverage

.. image:: https://readthedocs.org/projects/h11/badge/?version=latest
   :target: http://h11.readthedocs.io/en/latest/?badge=latest
   :alt: Documentation Status

This is a little HTTP/1.1 library written from scratch in Python,
heavily inspired by `hyper-h2 <https://hyper-h2.readthedocs.io/>`_.

It's a "bring-your-own-I/O" library; h11 contains no IO code
whatsoever. This means you can hook h11 up to your favorite network
API, and that could be anything you want: synchronous, threaded,
asynchronous, or your own implementation of `RFC 6214
<https://tools.ietf.org/html/rfc6214>`_ -- h11 won't judge you.
(Compare this to the current state of the art, where every time a `new
network API <https://trio.readthedocs.io/>`_ comes along then someone
gets to start over reimplementing the entire HTTP protocol from
scratch.) Cory Benfield made an `excellent blog post describing...

## AI interpretation — verify before relying

h11 is a pure-Python HTTP/1.1 protocol implementation that handles message parsing and serialization without any built-in I/O, letting you integrate it with any network stack (synchronous, asynchronous, or custom).

Verdict: h11 is a mature, well-tested HTTP/1.1 toolkit ideal for building custom HTTP clients and servers atop any I/O model. Zero dependencies, permissive licensing, and top-100 PyPI popularity make it a solid foundation layer, though its aging release cadence suggests it is feature-complete rather than actively evolving.

[View on SkillFed](https://skillfed.io/packages/h11) · [View on PyPI](https://pypi.org/project/h11/)