This is a Kotlin Multiplatform line-by-line transliteration port of tokio-rs/tokio.

Original Project: This port is based on tokio-rs/tokio. All design credit and project intent belong to the upstream authors; this repository is a faithful port to Kotlin Multiplatform with no behavioural changes intended.

This is an in-progress port. The goal is feature parity with the upstream Rust crate while providing a native Kotlin Multiplatform API. Every Kotlin file carries a // port-lint: source <path> header naming its upstream Rust counterpart so the AST-distance tool can track provenance.

The text below is reproduced and lightly edited from https://github.com/tokio-rs/tokio. It is the upstream project's own description and remains under the upstream authors' authorship; links have been rewritten to absolute upstream URLs so they continue to resolve from this repository.

TokioConf 2026 program and tickets are now available!

A runtime for writing reliable, asynchronous, and slim applications with the Rust programming language. It is:

• Fast: Tokio's zero-cost abstractions give you bare-metal performance.

• Reliable: Tokio leverages Rust's ownership, type system, and concurrency model to reduce bugs and ensure thread safety.

• Scalable: Tokio has a minimal footprint, and handles backpressure and cancellation naturally.

Website | Guides | API Docs | Chat

Tokio is an event-driven, non-blocking I/O platform for writing asynchronous applications with the Rust programming language. At a high level, it provides a few major components:

• A multithreaded, work-stealing based task scheduler.
• A reactor backed by the operating system's event queue (epoll, kqueue, IOCP, etc.).
• Asynchronous TCP and UDP sockets.

These components provide the runtime components necessary for building an asynchronous application.

A basic TCP echo server with Tokio.

Make sure you enable the full features of the tokio crate on Cargo.toml:

[dependencies]
tokio = { version = "1.52.2", features = ["full"] }

Then, on your main.rs:

use tokio::net::TcpListener;
use tokio::io::{AsyncReadExt, AsyncWriteExt};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let listener = TcpListener::bind("127.0.0.1:8080").await?;

    loop {
        let (mut socket, _) = listener.accept().await?;

        tokio::spawn(async move {
            let mut buf = [0; 1024];

            // In a loop, read data from the socket and write the data back.
            loop {
                let n = match socket.read(&mut buf).await {
                    // socket closed
                    Ok(0) => return,
                    Ok(n) => n,
                    Err(e) => {
                        eprintln!("failed to read from socket; err = {:?}", e);
                        return;
                    }
                };

                // Write the data back
                if let Err(e) = socket.write_all(&buf[0..n]).await {
                    eprintln!("failed to write to socket; err = {:?}", e);
                    return;
                }
            }
        });
    }
}

More examples can be found here. For a larger "real world" example, see the mini-redis repository.

To see a list of the available feature flags that can be enabled, check our docs.

First, see if the answer to your question can be found in the Guides or the API documentation. If the answer is not there, there is an active community in the Tokio Discord server. We would be happy to try to answer your question. You can also ask your question on the discussions page.

🎈 Thanks for your help improving the project! We are so happy to have you! We have a contributing guide to help you get involved in the Tokio project.

In addition to the crates in this repository, the Tokio project also maintains several other libraries, including:

• axum: A web application framework that focuses on ergonomics and modularity.

• hyper: A fast and correct HTTP/1.1 and HTTP/2 implementation for Rust.

• tonic: A gRPC over HTTP/2 implementation focused on high performance, interoperability, and flexibility.

• warp: A super-easy, composable, web server framework for warp speeds.

• tower: A library of modular and reusable components for building robust networking clients and servers.

• tracing (formerly tokio-trace): A framework for application-level tracing and async-aware diagnostics.

• mio: A low-level, cross-platform abstraction over OS I/O APIs that powers tokio.

• bytes: Utilities for working with bytes, including efficient byte buffers.

• loom: A testing tool for concurrent Rust code.

The Tokio repository contains multiple crates. Each crate has its own changelog.

• tokio - view changelog
• tokio-util - view changelog
• tokio-stream - view changelog
• tokio-macros - view changelog
• tokio-test - view changelog

Tokio will keep a rolling MSRV (minimum supported rust version) policy of at least 6 months. When increasing the MSRV, the new Rust version must have been released at least six months ago. The current MSRV is 1.71.

Note that the MSRV is not increased automatically, and only as part of a minor release. The MSRV history for past minor releases can be found below:

• 1.48 to now - Rust 1.71
• 1.39 to 1.47 - Rust 1.70
• 1.30 to 1.38 - Rust 1.63
• 1.27 to 1.29 - Rust 1.56
• 1.17 to 1.26 - Rust 1.49
• 1.15 to 1.16 - Rust 1.46
• 1.0 to 1.14 - Rust 1.45

Note that although we try to avoid the situation where a dependency transitively increases the MSRV of Tokio, we do not guarantee that this does not happen. However, every minor release will have some set of versions of dependencies that works with the MSRV of that minor release.

Tokio doesn't follow a fixed release schedule, but we typically make one minor release each month. We make patch releases for bugfixes as necessary.

For the purposes of making patch releases with bugfixes, we have designated certain minor releases as LTS (long term support) releases. Whenever a bug warrants a patch release with a fix for the bug, it will be backported and released as a new patch release for each LTS minor version. Our current LTS releases are:

• 1.47.x - LTS release until September 2026. (MSRV 1.70)
• 1.51.x - LTS release until March 2027. (MSRV 1.71)

Each LTS release will continue to receive backported fixes for at least a year. If you wish to use a fixed minor release in your project, we recommend that you use an LTS release.

To use a fixed minor version, you can specify the version with a tilde. For example, to specify that you wish to use the newest 1.47.x patch release, you can use the following dependency specification:

tokio = { version = "~1.47", features = [...] }

• 1.8.x - LTS release until February 2022.
• 1.14.x - LTS release until June 2022.
• 1.18.x - LTS release until June 2023.
• 1.20.x - LTS release until September 2023.
• 1.25.x - LTS release until March 2024.
• 1.32.x - LTS release until September 2024.
• 1.36.x - LTS release until March 2025.
• 1.38.x - LTS release until July 2025.
• 1.43.x - LTS release until March 2026.

This project is licensed under the MIT license.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Tokio by you shall be licensed as MIT, without any additional terms or conditions.

dependencies {
    implementation("io.github.kotlinmania:tokio-kotlin:0.1.0")
}

./gradlew build
./gradlew test

• macOS arm64
• Linux x64
• Windows mingw-x64
• iOS arm64 / simulator-arm64 (Swift export + XCFramework)
• JS (browser + Node.js)
• Wasm-JS (browser + Node.js)
• Android (API 24+)

See AGENTS.md and CLAUDE.md for translator discipline, port-lint header convention, and Rust → Kotlin idiom mapping.

This Kotlin port is distributed under the same MIT license as the upstream tokio-rs/tokio. See LICENSE (and any sibling LICENSE-* / NOTICE files mirrored from upstream) for the full text.

Original work copyrighted by the tokio authors.
Kotlin port: Copyright (c) 2026 Sydney Renee and The Solace Project.

Thanks to the tokio-rs/tokio maintainers and contributors for the original Rust implementation. This port reproduces their work in Kotlin Multiplatform; bug reports about upstream design or behavior should go to the upstream repository.