async-std VS tokio

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


A runtime for writing reliable asynchronous applications with Rust. Provides I/O, networking, scheduling, timers, ... (by tokio-rs)
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async-std tokio
19 196
3,828 24,515
0.8% 2.1%
5.3 9.5
2 months ago 2 days ago
Rust Rust
Apache License 2.0 MIT License
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 async-std. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-05-03.
  • Stabilizing async fn in traits in 2023 | Inside Rust Blog
    5 projects | /r/rust | 3 May 2023
    But maybe check out the discussion here or something (the blog post was linked on the end of it)
  • Anyone using io_uring?
    8 projects | /r/rust | 18 Aug 2022
    Have a look at these:
  • Any plans for built-in support of Vec2/Vec3/Vec4 in Rust?
    11 projects | /r/rust | 29 Jul 2022
    In fact, there are a lot of crates in Rust where in other programming languages, it would be included in the standard library. Examples are regex, random number generators, additional iterator methods, macros for other collections, num traits, loggers, HTTP libraries, error handling, async runtimes, serialization and deserialization, date and time, and many more.
  • 18 factors powering the Rust revolution, Part 2 of 3
    13 projects | | 10 Apr 2022
    Two major projects (non std lib but extremely commonly used) stand out in the area of async programming: Async std and Tokio - no doubt familiar to anyone that has turned an eye towards Rust for a second too long. Async architecture in general is likely very familiar to JavaScript programmers but in Rust there are some extra considerations (like ownership of the data that is thrown into an async function). Tokio is fast becoming a heavily supported and road tested async framework, with a thread scheduling runtime "baked in" that has learned from the history of Go, Erlang, and Java thread schedulers.
  • What are the side-effects of using different runtimes in the same codebase?
    2 projects | /r/rust | 21 Feb 2022
    Ah... and ?
  • Hey Rustaceans! Got an easy question? Ask here (51/2021)!
    7 projects | /r/rust | 21 Dec 2021
    async-std: Basically a Tokio alternative with a few different design decisions.
  • Why asynchronous Rust doesn't work
    3 projects | /r/programming | 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 | /r/rust | 14 Mar 2021
    And also, the actual PR never got merged.
    4 projects | /r/rust | 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.


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 2024-04-05.
  • On Implementation of Distributed Protocols
    23 projects | | 5 Apr 2024
    Being able to control nondeterminism is particularly useful for testing and debugging. This allows creating reproducible test environments, as well as discrete-event simulation for faster-than-real-time simulation of time delays. For example, Cardano uses a simulation environment for the IO monad that closely follows core Haskell packages; Sui has a simulator based on madsim that provides an API-compatible replacement for the Tokio runtime and intercepts various POSIX API calls in order to enforce determinism. Both allow running the same code in production as in the simulator for testing.
  • I pre-released my project "json-responder" written in Rust
    11 projects | | 21 Jan 2024
    tokio / hyper / toml / serde / serde_json / json5 / console
  • Cryptoflow: Building a secure and scalable system with Axum and SvelteKit - Part 0
    12 projects | | 4 Jan 2024
    tokio - An asynchronous runtime for Rust
  • Top 10 Rusty Repositories for you to start your Open Source Journey
    11 projects | | 19 Dec 2023
    3. Tokio
  • API Gateway, Lambda, DynamoDB and Rust
    5 projects | | 5 Dec 2023
    The AWS SDK makes use of the async capabilities in the Tokio library. So when you see async in front of a fn that function is capable of executing asynchronously.
  • The More You Gno: Monthly Updates - 6
    8 projects | /r/Gnoland | 30 Nov 2023
    Petar is also looking at implementing concurrency the way it is in Go to have a fully functional virtual machine as it is in the spec. This would likely attract more external contributors to developing the VM. One advantage of Rust is that, with the concurrency model, there is already an extensive library called Tokio which he can use. Petar stresses that this isn’t easy, but he believes it’s achievable, at least as a research topic around determinism and concurrency.
  • Consuming an SQS Event with Lambda and Rust
    7 projects | | 3 Nov 2023
    Another thing to point out is that async is a thing in Rust. I'm not going to begin to dive into this paradigm in this article, but know it's handled by the awesome Tokio framework.
  • netcrab: a networking tool
    4 projects | | 14 Oct 2023
    So I started by using Tokio, a popular async runtime. The docs and samples helped me get a simple outbound TCP connection working. The Rust async book also had a lot of good explanations, both practical and digging into the details of what a runtime does.
  • Thread-per-Core
    3 projects | | 6 Oct 2023
    Regarding the quote:

    > The Original Sin of Rust async programming is making it multi-threaded by default. If premature optimization is the root of all evil, this is the mother of all premature optimizations, and it curses all your code with the unholy Send + 'static, or worse yet Send + Sync + 'static, which just kills all the joy of actually writing Rust.

    Agree about the melodramatic tone. I also don't think removing the Send + Sync really makes that big a difference. It's the 'static that bothers me the most. I want scoped concurrency. Something like <>.

    Another thing I really hate about Rust async right now is the poor instrumentation. I'm having a production problem at work right now in which some tasks just get stuck. I wish I could do the equivalent of `gdb; thread apply all bt`. Looking forward to <> landing at least. It exists right now but is experimental and in my experience sometimes panics. I'm actually writing a PR today to at least use the experimental version on SIGTERM to see what's going on, on the theory that if it crashes oh well, we're shutting down anyway.

    Neither of these complaints would be addressed by taking away work stealing. In fact, I could keep doing down my list, and taking away work stealing wouldn't really help with much of anything.

  • PHP-Tokio – Use any async Rust library from PHP
    7 projects | | 27 Aug 2023
    The PHP <-> Rust bindings are provided by (our fork of with a bunch of UX improvements :).

    php-tokio's integrates the event loop with the event loop; async functionality is provided by the two event loops, in combination with PHP fibers through revolt's suspension API (I could've directly used the PHP Fiber API to provide coroutine suspension, but it was a tad easier with revolt's suspension API (, since it also handles the base case of suspension in the main fiber).

What are some alternatives?

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

Rocket - A web framework for Rust.

hyper - An HTTP library for Rust

futures-rs - Zero-cost asynchronous programming in Rust

smol - A small and fast async runtime for Rust

rayon - Rayon: A data parallelism library for Rust

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

crossbeam - Tools for concurrent programming in Rust

glommio - Glommio is a thread-per-core crate that makes writing highly parallel asynchronous applications in a thread-per-core architecture easier for rustaceans.

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

MIO - Metal I/O library for Rust.

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