#ui #dom #app #reactive #frontend


The minimal, obvious, graphical, web application interface

13 releases

0.2.3 Jun 5, 2020
0.2.2 May 11, 2020
0.2.1 Mar 27, 2020
0.1.6 Mar 16, 2020
0.0.1 Nov 28, 2019

#43 in GUI

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70 downloads per month

MIT license

1.5K SLoC


minimalist, obvious, graphical web application interface

release: Crates.io cicd

master: cicd

mogwai is a frontend DOM library for creating web applications. It is written in Rust and runs in your browser. It is an alternative to React, Backbone, Ember, Elm, Purescript, etc.


  • provide a declarative approach to creating and managing DOM nodes
  • encapsulate component state and compose components easily
  • explicate DOM updates
  • be small and fast (snappy af)

If mogwai achieves these goals, which I think it does, then maintaining application state, composing widgets and reasoning about your program will be easy. Furthermore, your users will be happy because their UI is snappy!


Here is an example of a button that counts its own clicks.

extern crate mogwai;
use mogwai::prelude::*;

let (tx, rx) =
    |n:&mut i32, _:&Event| -> String {
      *n += 1;
      if *n == 1 {
        "Clicked 1 time".to_string()
      } else {
        format!("Clicked {} times", *n)

  .rx_text("Clicked 0 times", rx)
  .tx_on("click", tx)

Here's that same example using the elm-like Component trait:

use mogwai::prelude::*;

pub struct Button {
  pub clicks: i32

pub enum ButtonIn {

pub enum ButtonOut {

impl Component for Button {
  type ModelMsg = ButtonIn;
  type ViewMsg = ButtonOut;
  type DomNode = HtmlElement;

  fn update(
    &mut self,
    msg: &ButtonIn,
    tx_view: &Transmitter<ButtonOut>,
    _subscriber: &Subscriber<ButtonIn>
  ) {
    match msg {
      ButtonIn::Click => {
        self.clicks += 1;

  fn view(
    tx: Transmitter<ButtonIn>,
    rx: Receiver<ButtonOut>
  ) -> Gizmo<HtmlElement> {
      .rx_text("Clicked 0 times", rx.branch_map(|msg| {
        match msg {
          ButtonOut::Clicks(n) => format!("Clicked {} times", n)
      .tx_on("click", tx.contra_map(|_| ButtonIn::Click))

Button{ clicks: 0 }


If you're interested in learning more - please read the introduction and documentation.


Rust is beginning to have a good number of frontend libraries. Most however, encorporate a virtual DOM with a magical update phase. Even in a languague that has performance to spare this step can cause unwanted slowness.

mogwai lives in a happy space just above "bare metal". It does this by providing the tools needed to declare exactly which parts of the DOM change and when.

These same tools encourage functional progamming patterns like encapsulation over inheritance (or traits, in this case).

Channel-like primitives and a declarative html builder are used to define components and then wire them together. Once the interface is defined and built, the channels are effectively erased and it's functions all the way down. There's no performance overhead from vdom, shadow dom, polling or patching. So if you prefer a functional style of programming with lots of maps and folds - or if you're looking to go vroom! then maybe mogwai is right for you and your team :)

made for rustaceans, by a rustacean

Another benefit of mogwai is that it is Rust-first. There is no requirement that you have npm or node. Getting your project up and running without writing any javascript is easy enough.


mogwai is snappy! Here is a very handwavey and sketchy todomvc benchmark:

mogwai performance benchmarking

ok - where do i start?

First you'll need new(ish) version of the rust toolchain. For that you can visit https://rustup.rs/ and follow the installation instructions.

Then you'll need wasm-pack.

For starting a new mogwai project we'll use the wonderful cargo-generate, which can be installed using cargo install cargo-generate.

Then run

cargo generate --git https://github.com/schell/mogwai-template.git

and give the command line a project name. Then cd into your sparkling new project and

wasm-pack build --target no-modules

Then, if you don't already have it, cargo install basic-http-server or use your favorite alternative to serve your app:

basic-http-server -a

Happy hacking! ☕ ☕ ☕

more examples please

For more examples, check out

the sandbox

the todomvc app

the benchmark suite

To build the examples use:

cd examples/whatever && wasm-pack build --target no-modules


Please consider sponsoring the development of this library!


~176K SLoC