MIO is a lightweight IO library for Rust with a focus on adding as little overhead as possible over the OS abstractions.

Currently a work in progress: Getting Started. Feedback can be posted on the PR.

Monthly Downloads: 234,276
Programming language: Rust
License: MIT License
Tags: Network Programming     Epoll     Non-blocking     Tcp     Udp     Io     Async    
Latest version: v0.6.19

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Mio – Metal IO

Mio is a lightweight I/O library for Rust with a focus on adding as little overhead as possible over the OS abstractions.

Crates.io [MIT licensed][mit-url] Build Status Build Status

API documentation

This is a low level library, if you are looking for something easier to get started with, see Tokio.


To use mio, first add this to your Cargo.toml:

mio = "0.6"

Then, add this to your crate root:

extern crate mio;


  • Non-blocking TCP, UDP
  • I/O event queue backed by epoll, kqueue, and IOCP
  • Zero allocations at runtime
  • Platform specific extensions


The following are specifically omitted from Mio and are left to the user or higher-level libraries.

  • File operations
  • Thread pools / multi-threaded event loop
  • Timers


Currently supported platforms:

  • Android
  • Bitrig
  • DragonFly BSD
  • FreeBSD
  • Linux
  • NetBSD
  • OpenBSD
  • Solaris
  • Windows
  • iOS
  • macOS

There are potentially others. If you find that Mio works on another platform, submit a PR to update the list!


A group of Mio users hang out on Gitter, this can be a good place to go for questions.


Interested in getting involved? We would love to help you! For simple bug fixes, just submit a PR with the fix and we can discuss the fix directly in the PR. If the fix is more complex, start with an issue.

If you want to propose an API change, create an issue to start a discussion with the community. Also, feel free to talk with us in Gitter.

Finally, be kind. We support the Rust Code of Conduct.

*Note that all licence references and agreements mentioned in the MIO README section above are relevant to that project's source code only.