tokio VS async-std

Compare tokio vs async-std and see what are their differences.


A runtime for writing reliable asynchronous applications with Rust. Provides I/O, networking, scheduling, timers, ... (by tokio-rs)


Async version of the Rust standard library (by async-rs)
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tokio async-std
70 13
13,967 3,056
3.8% 1.6%
9.6 5.5
6 days ago 19 days ago
Rust Rust
MIT License GNU General Public License v3.0 or later
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.


Posts with mentions or reviews of tokio. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2021-11-25.


Posts with mentions or reviews of async-std. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2021-11-13.
  • Why asynchronous Rust doesn't work
    3 projects | | 13 Nov 2021
    Go's solution is for the scheduler to notice after a while when a goroutine has blocked execution and to shift goroutines waiting their turn to another thread. async-std pondered a similar approach with tasks, but it proved controversial and was never merged.
  • Building static Rust binaries for Linux
    6 projects | | 17 Oct 2021
    This indicates curl, zlib, openssl, and libnghttp2 as well as a bunch of WASM-related things are being dynamically linked into my executable. To resolve this, I looked at the build features exposed by surf and found that it selects the "curl_client" feature by default, which can be turned off and replaced with "h1-client-rustls" which uses an HTTP client backed by rustls and async-std and no dynamically linked libraries. Enabling this build feature removed all -sys dependencies from androidx-release-watcher, allowing me to build static executables of it.
  • Rust async is colored, and that’s not a big deal
    4 projects | | 14 Mar 2021
    And also, the actual PR never got merged.
    4 projects | | 14 Mar 2021
    Many people believe that based on the blog post about it, but the PR was actually never merged, and the approach was abandoned due to various issues.
  • Rust's async isn't f#@king colored!
    4 projects | | 10 Mar 2021
    Async in rust needs a runtime (aka executor) to run. You can maybe get a better description from the rust docs. As an example, Tokio attempts to provide an interface for a developer that is minimal change to the more common blocking code. So you'd end up putting #[tokio::main] above your main function to spin up the executor and most of the rest of the code is similar to a non-async version with a few sprinkles of .await, which you can see in the hello world for tokio. In contrast, async-std provides a more hands-on/low-level approach. If you are unlucky enough to have libraries that choose different stacks to work on, you'll possibly (probably?) have to handle both.
  • Comparison of Rust async and Linux thread context switch time and memory use
    7 projects | | 11 Feb 2021
    Nothing so fancy.

    Each worker thread runs in a loop executing a queue of jobs. On every iteration it sets an atomic progress flag to true.

    The runtime in which it's contained polls its workers every 1-10ms, atomically swapping in false and checking to see if the previous value was also false - if so, it steals its task queue and spins up another worker to execute it.

  • What is the best way to ask for user input while simultaneously outputting to the console?
    2 projects | | 16 Jan 2021
    async-std uses blocking I/O on a background thread. tokio does the same for its equivalent API.
  • async-std v1.9.0 has been released!
    2 projects | | 15 Jan 2021
    Looking at, it seems the deprecated APIs were hidden behind a feature flag called unstable which is understood to not guarantee such backwards compatibility.
    2 projects | | 15 Jan 2021
  • Tokio, the async runtime for Rust, hits 1.0
    12 projects | | 23 Dec 2020
    if I understand correctly, smol was created by the async-std folks, and async-std now uses it as its runtime

What are some alternatives?

When comparing tokio and async-std you can also consider the following projects:

rayon - Rayon: A data parallelism library for Rust

Rocket - A web framework for Rust.

sqlx - 🧰 The Rust SQL Toolkit. An async, pure Rust SQL crate featuring compile-time checked queries without a DSL. Supports PostgreSQL, MySQL, SQLite, and MSSQL.

smol - A small and fast async runtime for Rust

hyper - An HTTP library for Rust

bevy - A refreshingly simple data-driven game engine built in Rust

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

reqwest - An easy and powerful Rust HTTP Client

actix-web - Actix Web is a powerful, pragmatic, and extremely fast web framework for Rust.

winit - Window handling library in pure Rust

sled - the champagne of beta embedded databases

async-std-hyper - How to run Hyper on async-std