Browser extensions,
entirely in Rust.

Write type-safe browser extensions with proc macros and Leptos. Compiled to WebAssembly. Chrome & Firefox. Zero JavaScript by hand.

Get Started View on GitHub

lib.rs

#[oxichrome::extension(
    name = "My Extension",
    permissions = ["storage", "tabs"]
)]
struct App;

#[oxichrome::popup]
fn Popup() -> impl IntoView {
    let count = RwSignal::new(0);
    view! {
        <button on:click=move |_| count.update(|c| *c += 1)>
            {move || count.get()}
        </button>
    }
}

Features

Write less. Ship more.

Everything you need to build browser extensions without leaving Rust.

Proc Macro DX

Four attributes (#[extension], #[background], #[popup], #[on]) replace hundreds of lines of boilerplate.

Type-Safe APIs

Chrome and Firefox APIs wrapped in typed, async Rust interfaces. Errors at compile time, not in production.

WebAssembly Output

Your Rust compiles to Wasm. Small binaries, near-native speed, sandboxed execution inside the browser.

Leptos UI

Build popup and options pages with Leptos fine-grained reactivity. No virtual DOM, no JS framework.

One Command Build

cargo oxichrome build compiles your crate, generates manifest.json, JS shims, and HTML for Chromium or Firefox.

Zero JavaScript

You never write JS. The build tool generates the glue code that wires Wasm exports to Chrome listeners.

API

Four macros. Full control.

Each attribute maps to a Chrome extension concept. If you know what a popup is, you know how to build one.

Defines your extension’s identity — name, version, permissions. Generates manifest.json at build time.

What you write

lib.rs

#[oxichrome::extension(
    name = "Color Picker",
    version = "0.1.0",
    permissions = ["storage", "activeTab"]
)]
struct ColorPickerExt;

What gets generated

expanded

// manifest.json
{
  "manifest_version": 3,
  "name": "Color Picker",
  "version": "0.1.0",
  "permissions": ["storage", "activeTab"]
}

Type Safety

Callback hell → async Rust.

Every Chrome API is wrapped in a type-safe, async Rust interface.

JavaScript / Storage

// callback-based, untyped
chrome.storage.local.get("count", (result) => {
  const count = result.count;
  console.log(count + 1);
});

→

Rust / Storage

// async, generic, type-safe
let count: Option<i32> =
    oxichrome::storage::get("count").await?;

oxichrome::log!("{}", count.unwrap_or(0) + 1);

JavaScript / Events

// manual listener registration
chrome.runtime.onInstalled.addListener((details) => {
  if (details.reason === "install") {
    chrome.storage.local.set({ count: 0 });
  }
});

→

Rust / Events

// declarative attribute, async
#[oxichrome::on(runtime::on_installed)]
async fn on_install(details: JsValue) {
    oxichrome::storage::set("count", &0i32)
        .await.ok();
}

JavaScript / UI

// manual DOM, no reactivity
const btn = document.getElementById("btn");
const display = document.getElementById("count");
let count = 0;

btn.addEventListener("click", () => {
  count++;
  display.textContent = count;
});

display.textContent = count;

→

Rust / UI

// fine-grained reactivity with Leptos
#[oxichrome::popup]
fn Popup() -> impl IntoView {
    let n = RwSignal::new(0);
    view! {
        <span>{move || n.get()}</span>
        <button on:click=move |_| n.set(n.get() + 1)>
            "+"
        </button>
    }
}

Examples

See it in action.

Full working extensions in a single Rust file. Try the interactive preview.

A minimal popup extension with persistent state. Click a button, the count increments and survives browser restarts via chrome.storage.

Counter Extension

Architecture

Five crates. One command.

A clean separation of concerns: macros, runtime, facade, analysis, and CLI.

Your code

→

oxichrome-macros

→

compile to Wasm

→

oxichrome-build

→

dist/chromium/ or dist/firefox/

Macros

oxichrome-macros

Proc macros that expand your #[extension], #[popup], #[on] attributes into wasm_bindgen exports.

Runtime

oxichrome-core

Async Rust wrappers around chrome.* JS APIs — storage, tabs, runtime, messaging.

Facade

oxichrome

The crate you depend on. Re-exports macros and core. This is your one dependency.

Analysis

oxichrome-build

Parses your source to discover annotated functions, popup components, and event handlers.

CLI

oxichrome-cli

cargo oxichrome build — orchestrates wasm-pack, source analysis, and artifact generation.

Get Started

Five steps. Five minutes.

terminal

$ cargo install cargo-oxichrome

Installing cargo-oxichrome v0.2.0 Installed ~/.cargo/bin/cargo-oxichrome

$ cargo oxichrome new my-extension

Created my-extension/Cargo.toml Created my-extension/src/lib.rs

$ cd my-extension && cargo oxichrome build

[oxichrome] Building: my-extension Compiling my-extension v0.2.0 Finished release [optimized] [oxichrome] Build complete → dist/chromium/

Install the CLI

One cargo install gets you the oxichrome build tool.

Scaffold a project

Creates Cargo.toml with the oxichrome dependency, and a starter lib.rs.

Write your extension

Use #[extension], #[popup], #[background] in Rust.

Build

cargo oxichrome build compiles to WASM and generates manifest, JS shims, and HTML.

Load in browser

Chrome: load dist/chromium/ in chrome://extensions. Firefox: load dist/firefox/ in about:debugging.

Ready?

Start building Chrome extensions in Rust today.

One command to install. Five minutes to your first extension.