tokio-kotlin in Kotlin

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.
Porting status
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.
Upstream README — tokio-rs/tokio
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!
Tokio
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
Overview
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.
Example
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.
Getting Help
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.
Contributing
:balloon: 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.
Related Projects
In addition to the crates in this repository, the Tokio project also maintains
several other libraries, including:
Changelog
The Tokio repository contains multiple crates. Each crate has its own changelog.
Supported Rust Versions
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.
Release schedule
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.
Bug patching policy
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 = [...] }
Previous LTS releases
License
This project is licensed under the MIT license.
Contribution
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.
About this Kotlin port
Installation
dependencies {
implementation("io.github.kotlinmania:tokio-kotlin:0.1.0")
}
Building
./gradlew build
./gradlew test
Targets
- 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+)
Porting guidelines
See AGENTS.md and CLAUDE.md for translator discipline, port-lint header convention, and Rust → Kotlin idiom mapping.
License
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.
Acknowledgments
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.