Neutralinojs — Lightweight Cross-Platform Desktop Apps

Introduction

Neutralinojs lets you build cross-platform desktop applications using standard web technologies while keeping the binary size under 5 MB. Instead of shipping Chromium, it talks to the operating system's native webview, producing dramatically smaller and faster apps than Electron.

What Neutralinojs Does

• Provides a lightweight runtime that uses the OS-native webview (WebKitGTK, Cocoa WKWebView, or Edge WebView2)
• Exposes file system, OS shell, clipboard, and window APIs through a JavaScript client library
• Produces self-contained binaries for Windows, macOS, and Linux from a single codebase
• Supports a hot-reload development workflow with the neu run command
• Offers both window and Chrome mode (opens in the default browser) for flexible UI rendering

Architecture Overview

The Neutralinojs runtime is a small C++ binary that starts an HTTP server on localhost and opens the OS webview pointed at it. The frontend communicates with the runtime over WebSockets using a JSON-RPC protocol. Native operations (file I/O, process spawning, system info) are handled by the C++ backend and exposed as async JavaScript functions via the Neutralino global object. Extensions allow running background processes in any language that speaks the same WebSocket protocol.

Self-Hosting & Configuration

• Install the CLI globally: npm i -g @neutralinojs/neu
• Configure app metadata, permissions, and window settings in neutralino.config.json
• Use neu update to download the latest runtime binaries
• Enable only the native APIs your app needs via the nativeAllowList setting
• Build for all three platforms at once with neu build (cross-compilation from any host)

Key Features

• Sub-5 MB binary size versus 150+ MB for Electron apps
• OS-native webview eliminates Chromium overhead and memory bloat
• Secure permission model — APIs are opt-in via an allowlist
• Extension system for running backend processes in Node.js, Python, or any language
• Hot-reload development with automatic frontend refresh

Comparison with Similar Tools

• Electron — bundles Chromium for full browser compatibility but produces large binaries and high RAM usage
• Tauri — Rust-based, also uses native webview; richer API surface but requires Rust toolchain
• Wails — Go backend with native webview; best when backend logic is written in Go
• NW.js — Chromium-based like Electron; similar size and memory tradeoffs
• Progressive Web Apps — no installation needed but limited access to native OS APIs

FAQ

Q: Does Neutralinojs support React, Vue, or Svelte? A: Yes. Any frontend framework that outputs HTML/CSS/JS works. Point the framework build output to the Neutralinojs resources directory.

Q: How small are the output binaries? A: Typically 2-5 MB for the runtime plus your frontend assets, compared to 150+ MB for Electron.

Q: Can I access the file system and run shell commands? A: Yes. The Neutralino.filesystem and Neutralino.os APIs provide full access, gated by the config allowlist.

Q: Is there a way to run backend code? A: Yes. The extensions API lets you spawn a sidecar process (Node.js, Python, etc.) that communicates with the frontend via WebSockets.

Sources

• https://github.com/neutralinojs/neutralinojs
• https://neutralino.js.org/docs