---
id: caio
version: "0.12.2"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# caio — Asynchronous file IO for Linux MacOS or Windows.

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install caio
uv add caio
poetry add caio

## Description

Python wrapper for AIO
======================

Python bindings for async file I/O on Linux and a pure-Python/thread fallback
for other platforms.

Three backends are available:

| Backend         | Kernel | Notes                                                      |
|-----------------|--------|------------------------------------------------------------|
| `linux_uring`   | ≥ 5.6  | io_uring - shared ring buffers, zero-syscall completions   |
| `linux_aio`     | ≥ 4.18 | kernel AIO (`io_submit` / `io_getevents`), `O_DIRECT` only |
| `thread_aio`    | any    | pthreads pool, portable                                    |
| `python_aio`    | any    | pure Python, no C extension required                       |

Example
-------

```python
import asyncio
from caio import AsyncioContext

loop = asyncio.get_event_loop()

async def main():
    # max_requests=128 by default
    ctx = AsyncioContext(max_requests=128)

    with open("test.file", "wb+") as fp:
        fd = fp.fileno()

        # Execute one write operation
        await ctx.write(b"Hello world", fd, offset=0)

        # Execute one read operation
        print(await ctx.read(32, fd, offset=0))

        # Execute one...

## AI interpretation — verify before relying

caio provides async file I/O for Python via multiple backends: io_uring and kernel AIO on Linux, thread pools, or pure Python fallback. It integrates with asyncio for non-blocking file operations.

Verdict: caio is a well-maintained, dependency-free async file I/O library with permissive licensing and no known vulnerabilities. It offers high-performance backends on Linux and portable fallbacks elsewhere, making it suitable for production use where async disk I/O is needed.

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