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tokio-rs

tokio-rs/tokio

An asynchronous runtime for Rust providing task scheduling, non-blocking I/O, networking, and timers for building reliable network applications.

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What is it?

Tokio is an event-driven, non-blocking I/O platform for writing asynchronous applications in Rust. It bundles a multithreaded, work-stealing task scheduler, a reactor backed by the operating system's event queue (epoll, kqueue, IOCP and similar), and asynchronous TCP and UDP sockets.

It targets developers building network services and other I/O-heavy programs who need many concurrent connections without dedicating a thread to each one. Applications enable the feature flags they need, then use async/await with the runtime's spawn, timers, and synchronization primitives.

The project is part of a wider ecosystem that includes the axum web framework, hyper HTTP implementation, tonic gRPC library, tower middleware abstractions, and the tracing diagnostics framework.

Key features

  • 01Multithreaded, work-stealing task scheduler
  • 02Non-blocking TCP and UDP sockets
  • 03Reactor built on epoll, kqueue, and IOCP
  • 04Timers and async synchronization primitives
  • 05Feature flags let projects include only needed components

Use cases

  • Building high-concurrency TCP or UDP network servers in Rust
  • Writing async clients that call many services concurrently
  • Running I/O-bound background tasks with timers and cancellation

Quick start

  1. 1

    Add Tokio to Cargo.toml with the full feature set

    tokio = { version = "1.54.1", features = ["full"] }
  2. 2

    Write the TCP echo server example in main.rs and run the project with cargo

Things to know

  • Requires the Rust toolchain, with a minimum supported Rust version of 1.85.
  • Tokio is a runtime library, so it is only useful inside a Rust project that you build yourself.

Topics

#asynchronous#rust#networking#runtime#concurrency#tcp

FAQ

What is tokio?
An asynchronous runtime for Rust providing task scheduling, non-blocking I/O, networking, and timers for building reliable network applications. Tokio is an event-driven, non-blocking I/O platform for writing asynchronous applications in Rust. It bundles a multithreaded, work-stealing task scheduler, a reactor backed by the operating system's event queue (epoll, kqueue, IOCP and similar), and asynchronous TCP and UDP sockets.
Is tokio free to use? What license does it have?
tokio is open source under the MIT license. Check the license terms before using it in commercial products.
Is tokio still maintained?
Actively maintained. The last commit to tokio was on Oct 24, 2026.
What can I use tokio for?
Building high-concurrency TCP or UDP network servers in Rust Writing async clients that call many services concurrently Running I/O-bound background tasks with timers and cancellation
How do I install tokio?
Add Tokio to Cargo.toml with the full feature set: tokio = { version = "1.54.1", features = ["full"] } Write the TCP echo server example in main.rs and run the project with cargo
Where can I get tokio?
The source code and installation instructions are on GitHub: https://github.com/tokio-rs/tokio

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