#async-http #http-request #http #client #async #request


Async Lightweight HTTP Client: A async http client library that using system library to reduce binary size if possible. (Currently under heavy development)

10 releases

0.3.0-alpha.4 Apr 13, 2024
0.3.0-alpha.3 Apr 12, 2024
0.2.2 Oct 10, 2023
0.2.1 May 8, 2023
0.1.0 Nov 21, 2022

#92 in HTTP client

MIT license


Async Lightweight HTTP Client (aka ALHC)


This library is still in development and VERY UNSTABLE, please don't use it in production environment.

github.com crates.io docs.rs

What if we need async but also lightweight http client without using such a large library like reqwest, isahc or surf?

ALHC is a async http client library that using System library to reduce binary size and provide async request feature.

HTTPS Example:

use alhc::prelude::*;
use alhc::*;

use pollster::FutureExt;

fn main() -> DynResult {
    let client = get_client_builder().build().unwrap();

    let r = client
        .header("user-agent", "alhc/0.2.0")
        .body_string("Hello World!".repeat(20))



Our little request example https with release build can be 182 KB, which is smaller than tinyget's http example. If we use rustc nightly feature plus build-std and panic_immediate_abort, it'll be incredibly 65 KB!

Currently work in progress and support Windows (Using WinHTTP) and unix-like system (including macOS) (Using System libcurl by wraping isahc crate (Will be replaced by simplier curl crate binding)).

Platform Status

Name Status Note
Windows Working Maybe unstable (To be optimized)
macOS Working Simple wrapper of isahc crate
Linux Working Simple wrapper of isahc crate


  • async_t_boxed: Use async-trait instead of async-t, which requires 1.75+ version of rustc but with zero-cost. Default is disabled.
  • serde: Can give you the ability of send/receive json data without manually call serde_json. Default is disabled.
  • anyhow: Use Result type from anyhow crate instead Result<T, Box<dyn std::error::Error>>. Default is disabled.

Minimum binary size on unix-like platform guideline

For Unix-like system like linux or macOS which have builtin libcurl on almost all desktop version, you have to install all the development packages that curl crate needs to dynamic link these libraries. For an example, on Ubuntu, you need to install libcurl4-openssl-dev and zlib1g-dev for a dynamic linkage. Else curl crate will build from source and static link them and heavily impact binary size.

Compilation binary size comparison

Note: the size optimization argument is: cargo +nightly run --release -Z build-std=core,alloc,std,panic_abort -Z build-std-features=panic_immediate_abort --target [TARGET] --example [EXAMPLE] and some configuration in Cargo.toml

Name Windows (x86_64) Windows (i686) Windows (aarch64) macOS (x86_64) macOS (aarch64) Linux (x86_64)
example https 468,992 402,944 296,960 4,078,936 4,395,400 18,051,064
example https release 181,248 162,816 200,192 729,304 719,192 850,704
example https release with size optimization 75,264 66,048 59,392 444,680 453,064 465,480
example parallel 571,904 486,912 393,216 4,250,296 4,572,120 19,612,824
example parallel release 190,464 170,496 229,888 737,536 735,752 862,992
example parallel release with size optimization 80,896 71,680 66,560 452,912 453,112 469,576
example sequential 472,064 405,504 302,080 4,069,368 4,373,352 18,048,624
example sequential release 182,784 164,864 203,264 729,296 719,176 850,704
example sequential release with size optimization 76,800 68,096 60,928 448,776 453,064 465,480


~420K SLoC