Hot reload Rust backend logic inside mobile apps — no rebuilds, no reinstalls.

Getting Started • Architecture • Documentation • Roadmap • Contributing

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Befu is a high-performance cross-platform framework for building mobile and web applications using React or SolidJS for the UI and Rust for business logic. It features a custom, low-latency bridge and a dynamic hot-reload system for native code.

Key Features

• Zero-Click Hot Reload: Update native Rust logic on-device in approximately 1 second without full app rebuilds or reinstalls.
• Framework Agnostic: Native support for React and SolidJS.
• Typed Bridge: High-performance communication layer between WebView and Rust.
• Modern Scaffolding: Create complete cross-platform monorepos instantly via create-befu-app.
• Engineering Tools: Built-in doctor and bootstrap scripts to automate environment management.

Demo

Edit a Rust command and save; the application updates instantly without losing internal state.

Table of Contents

• Why Befu?
• Example Usage
• Architecture
• Quick Start
• Scaffold A New App
• Contributing
• License

Why Befu?

Traditional mobile development involves significant wait times for Gradle or Xcode builds following every backend or business logic change. Befu eliminates this friction:

• Save Rust to update the application instantly.
• Unified development across platforms.
• Persistent mobile app environment during logic swaps.
• Native performance with web-like iteration speeds.

Example Usage

Rust Backend

Define high-performance logic using procedural macros:

#[befu::command]
fn calculate_fast(args: MyArgs) -> MyResult {
    // Rust computation logic
    MyResult { score: 100 }
}

Frontend (React/Solid)

Invoke native code with a typed promise API:

import { invoke } from '@befu/bridge'

const result = await invoke('calculate_fast', { id: 1 })
console.log(result.score) // 100

Platform Support & Status

Feature	Android	iOS	Web
Bridge UI	✅	✅	✅
Hot Reload	✅ (Side-loading)	⚠️ (Bundled Only)	✅ (Vite HMR)
Production	🚧 Beta	🚧 Alpha	✅ Stable

Note: iOS hot-reloading is currently limited to bundled logic due to App Store dynamic loading restrictions. We are prioritizing Android-first high-frequency DX.

Security Model

Befu is designed with a strict "Dev vs Prod" boundary. The dynamic library loading required for hot-reloading is gated behind feature flags and is intended to be stripped from production binaries to eliminate remote code execution vectors.

Befu utilizes a dynamic-loading registry to swap logic at the binary boundary.

graph TD
    UI[Web UI / React & Solid] -->|invoke| Bridge[Befu Bridge / TS]
    Bridge -->|WebView Messaging| Core[Befu Core / Rust]
    Core -->|Hot Dispatch| App[Befu App / Rust Logic]
    Watcher[Rust Watcher / Scripts] -->|Sync Binaries| Files[App Sandbox]

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Quick Start

1. Environment Audit

Verify your system configuration for native Rust and mobile development:

bun run doctor

2. Bootstrap

Initialize dependencies and prepare platform-specific assets:

bun run bootstrap

3. Launch Development

Start the full development cycle for your target platform:

bun run a:dev  # Android Development
# OR
bun run i:dev  # iOS Development

Scaffold A New App

Automated project initialization using the official scaffolder:

bunx create-befu-app --name my-app --framework react --platform both --yes

Tip

If your local environment cache is stale, pin the latest release: bunx create-befu-app@0.1.5 [...]

Contributing

Contributions from the community are encouraged. Refer to the Contributing Guide to begin.

License

Befu is open-source software licensed under the MIT License.

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Made with love ❤️