# sniffio

> Sniff out which async library your code is running under

- **URL**: https://www.freshcrate.ai/projects/sniffio
- **Author**: pypi
- **Category**: Frameworks
- **Latest version**: `1.3.1` (2026-04-21)
- **License**: MIT OR Apache-2.0
- **Source**: https://github.com/python-trio/sniffio
- **Homepage**: https://pypi.org/project/sniffio/
- **Language**: Python
- **GitHub**: 148 stars, 27 forks
- **Registry**: pypi (`sniffio`)
- **Tags**: `async`, `asyncio`, `pypi`, `trio`

## Description

.. image:: https://img.shields.io/badge/chat-join%20now-blue.svg
   :target: https://gitter.im/python-trio/general
   :alt: Join chatroom

.. image:: https://img.shields.io/badge/docs-read%20now-blue.svg
   :target: https://sniffio.readthedocs.io/en/latest/?badge=latest
   :alt: Documentation Status

.. image:: https://img.shields.io/pypi/v/sniffio.svg
   :target: https://pypi.org/project/sniffio
   :alt: Latest PyPi version
   
.. image:: https://img.shields.io/conda/vn/conda-forge/sniffio.svg
   :target: https://anaconda.org/conda-forge/sniffio 
   :alt: Latest conda-forge version   

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

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

=================================================================
sniffio: Sniff out which async library your code is running under
=================================================================

You're writing a library. You've decided to be ambitious, and support
multiple async I/O packages, like `Trio
<https://trio.readthedocs.io>`__, and `asyncio
<https://docs.python.org/3/library/asyncio.html>`__, and ... You've
written a bunch of clever code to handle all the differences. But...
how do you know *which* piece of clever code to run?

This is a tiny package whose only purpose is to let you detect which
async library your code is running under.

* Documentation: https://sniffio.readthedocs.io

* Bug tracker and source code: https://github.com/python-trio/sniffio

* License: MIT or Apache License 2.0, your choice

* Contributor guide: https://trio.readthedocs.io/en/latest/contributing.html

* Code of conduct: Contributors are requested to follow our `code of
  conduct
  <https://trio.readthedocs.io/en/latest/code-of-conduct.html>`_
  in all project spaces.

This library is maintained by the Trio project, as a service to the
async Python community as a whole.


Quickstart
----------

.. code-block:: python3

   from sniffio import current_async_library
   import trio
   import asyncio

   async def print_library():
       library = current_async_library()
       print("This is:", library)

   # Prints "This is trio"
   trio.run(print_library)

   # Prints "This is asyncio"
   asyncio.run(print_library())

For more details, including how to add support to new async libraries,
`please peruse our fine manual <https://sniffio.readthedocs.io>`__.

## Recent releases

| Version | Date | Urgency | Changes |
| --- | --- | --- | --- |
| `1.3.1` | 2026-04-21 | Low | Imported from PyPI (1.3.1) |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |
| `master@2026-03-06` | 2026-03-06 | Low | Latest activity on master branch |

## Citation

- HTML: https://www.freshcrate.ai/projects/sniffio
- Markdown: https://www.freshcrate.ai/projects/sniffio.md
- Dependencies JSON: https://www.freshcrate.ai/api/projects/sniffio/deps

_Generated by freshcrate.ai. Indexes pypi releases for AI-agent ecosystem packages._