AnyIO is an asynchronous networking and concurrency library that works on top of either asyncio_ or Trio_. It implements Trio-like structured concurrency_ (SC) on top of asyncio and works in harmony with the native SC of Trio itself.

Applications and libraries written against AnyIO's API will run unmodified on either asyncio_ or Trio_. AnyIO can also be adopted into a library or application incrementally – bit by bit, no full refactoring necessary. It will blend in with the native libraries of your chosen backend.

To find out why you might want to use AnyIO's APIs instead of asyncio's, you can read about it here.

Documentation

View full documentation at: https://anyio.readthedocs.io/

Features

AnyIO offers the following functionality:

Task groups (nurseries_ in trio terminology)
High-level networking (TCP, UDP and UNIX sockets)

Happy eyeballs_ algorithm for TCP connections (more robust than that of asyncio on Python

3.8)

async/await style UDP sockets (unlike asyncio where you still have to use Transports and

Protocols)

A versatile API for byte streams and object streams
Inter-task synchronization and communication (locks, conditions, events, semaphores, object

streams and futures)

Worker threads
Subprocesses
Subinterpreter support for code parallelization (on Python 3.13 and later)
Asynchronous file I/O (using worker threads)
Signal handling
Asynchronous versions of the functools_ and itertools_ modules

AnyIO also comes with its own pytest_ plugin which also supports asynchronous fixtures. It even works with the popular Hypothesis_ library.

Security contact information

To report a security vulnerability, please use the Tidelift security contact_. Tidelift will coordinate the fix and disclosure.

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