Neutralinojs

Neutralino.js Platform Skill

Consolidated skill for building cross-platform desktop applications with Neutralino.js. Use decision trees below to find the right APIs and configuration options, then load detailed references.

When to Apply

• Building desktop utilities with file system operations
• Executing system commands or managing processes
• Creating apps with tray icons, notifications, or clipboard integration
• Accessing system information (CPU, memory, displays)

Critical Rules

Follow these rules in all Neutralino.js code:

1. Always use neu create <path> for new projects unless explicitly asked to create from scratch.
2. Import @neutralinojs/lib for frontend frameworks (React, Vue, etc.) instead of including neutralino.js directly.
3. Never use tokenSecurity: none when exposing native APIs - always use one-time (default) for security.
4. Configure nativeAllowList and nativeBlockList to restrict API access and enhance security.
5. Call Neutralino.init() before using any native API methods.
6. Handle window close events properly using events.on('windowClose') - never rely solely on the close button.
7. Initialize First: Call Neutralino.init() before any native API usage, see below:

// WRONG - calling APIs before initialization
await Neutralino.os.getEnv('USER');

// RIGHT - initialize then use APIs
Neutralino.init();
await Neutralino.os.getEnv('USER');

Handle Window Close: Always implement windowClose handler to prevent hanging processes

// WRONG - missing exit handler
Neutralino.init();

// RIGHT - proper cleanup on window close
Neutralino.init();
Neutralino.events.on("windowClose", () => {
  Neutralino.app.exit();
});

Error Code Patterns: Native API errors use specific codes (NE_FS_*, NE_OS_*, NE_RT_*)

// Check for specific filesystem errors
try {
  await Neutralino.filesystem.readFile('./config.txt');
} catch(err) {
  if (err.code === 'NE_FS_NOPATHE') {
    // File doesn't exist
  } else if (err.code === 'NE_FS_FILRDER') {
    // File read error
  }
}

How to Use This Skill

Reference File Structure

Neutralino.js references follow a hierarchical structure. Cross-cutting concepts and how-to guides are separate.

API References in ./references/api/:

• overview.md - All API namespaces and architecture
• app.md - Application lifecycle, config, broadcasting
• window.md - Window management (create, focus, size, tray)
• filesystem.md - File operations, watchers, paths
• os.md - OS operations, environment variables, spawning processes
• storage.md - Key-value storage (SQLite-based)
• clipboard.md - System clipboard access
• computer.md - System info (memory, OS version)
• events.md - Event system (on, off, dispatch, broadcast)
• extensions.md - Extension communication
• custom.md - Custom method execution
• resources.md - Bundle resource access
• server.md - Server info and configuration
• updater.md - Auto-updater functionality
• init.md - Initialization API
• error-codes.md - Error code reference
• global-variables.md - Predefined global variables

CLI Reference in ./references/cli/:

• neu-cli.md - All CLI commands (create, run, build, update, etc.)
• internal-cli-arguments.md - Framework binary CLI arguments

Configuration in ./references/configuration/:

• neutralino.config.json.md - Complete config reference
• modes.md - Application modes (window, browser, cloud, chrome)
• project-structure.md - Project directory layout

Getting Started in ./references/getting-started/:

• introduction.md - What is Neutralino.js, features, comparisons
• using-frontend-libraries.md - React, Vue, Angular integration

How-To Guides in ./references/how-to/:

• extensions-overview.md - Building and using extensions
• auto-updater.md - Implementing auto-updates

Distribution in ./references/distribution/:

• overview.md - Building and distributing applications

Reading Order

1. Start with getting-started/introduction.md for overview
2. Then read based on your task:
   • Creating new app -> cli/neu-cli.md (neu create)
   • Using native APIs -> api/overview.md + specific namespace
   • Window management -> api/window.md + configuration/modes.md
   • File operations -> api/filesystem.md
   • Configuration -> configuration/neutralino.config.json.md
   • Building extensions -> how-to/extensions-overview.md
   • Auto-updater -> how-to/auto-updater.md
   • Frontend integration -> getting-started/using-frontend-libraries.md
   • Distribution -> distribution/overview.md

Example Paths

./references/getting-started/introduction.md       # Start here
./references/cli/neu-cli.md                         # CLI commands
./references/api/overview.md                        # All APIs overview
./references/api/filesystem.md                       # File operations
./references/configuration/neutralino.config.json.md # Config reference
./references/how-to/extensions-overview.md          # Extensions
./references/api/window.md                          # Window management

Quick Decision Trees

"I want to create a new Neutralino.js app"

Create app?
├─ Quick start with default template -> neu create myapp
├─ Use custom template -> neu create myapp --template=<account>/<repo>
├─ Integrate with frontend framework -> getting-started/using-frontend-libraries.md
└─ From scratch (expert) -> configuration/neutralino.config.json.md

"I need to manage windows"

Window management?
├─ Create/show window -> api/window.md (window.create, window.show)
├─ Set window size/position -> api/window.md (window.setSize, window.setPosition)
├─ Window focus/maximize/minimize -> api/window.md (window.focus, window.maximize, window.minimize)
├─ System tray icon -> api/window.md (window.setTrayOptions)
├─ Transparent window -> configuration/neutralino.config.json.md (modes.window.transparent)
├─ Borderless window -> configuration/neutralino.config.json.md (modes.window.borderless)
└─ Fullscreen mode -> api/window.md (window.enterFullScreen)

"I need to work with files"

File operations?
├─ Read text file -> api/filesystem.md (readFile)
├─ Write text file -> api/filesystem.md (writeFile)
├─ Read directory -> api/filesystem.md (readDirectory)
├─ Create/remove directory -> api/filesystem.md (createDirectory, remove)
├─ Copy/move files -> api/filesystem.md (copy, move)
├─ Watch file changes -> api/filesystem.md (createWatcher)
├─ File stats (exists, size, modified) -> api/filesystem.md (getStats)
├─ Path operations -> api/filesystem.md (getAbsolutePath, getRelativePath)
└─ File permissions -> api/filesystem.md (getPermissions, setPermissions)

"I need OS-level operations"

OS operations?
├─ Execute system command -> api/os.md (execCommand)
├─ Get environment variable -> api/os.md (getEnv)
├─ Set environment variable -> api/os.md (setEnv)
├─ Spawn process with I/O -> api/os.md (spawnProcess)
├─ Get OS info -> api/computer.md (getOsInfo)
├─ Get memory info -> api/computer.md (getMemoryInfo)
├─ Open external URL -> api/os.md (open)
└─ Path constants (NL_PATH, NL_CWD) -> api/global-variables.md

"I need data storage"

Storage?
├─ Simple key-value storage -> api/storage.md (getData, setData, putData)
├─ Persist data across app restarts -> api/storage.md
└─ Custom database -> how-to/extensions-overview.md (build extension)

"I need to handle events"

Events?
├─ Window close event -> api/events.md (windowClose)
├─ Window focus/blur -> api/events.md (windowFocus, windowBlur)
├─ Tray menu click -> api/events.md (trayMenuItemClicked)
├─ App instance events -> api/events.md (appClientConnect, appClientDisconnect)
├─ Extension events -> api/events.md (extensionReady, extClientConnect)
└─ Custom events -> api/events.md (dispatch, broadcast)

"I need to build and distribute"

Build & distribute?
├─ Build for current platform -> cli/neu-cli.md (neu build)
├─ Create portable ZIP -> cli/neu-cli.md (--release)
├─ Single-file executable -> cli/neu-cli.md (--embed-resources)
├─ Auto-updater -> how-to/auto-updater.md
└─ Distribution overview -> distribution/overview.md

"I need to use extensions"

Extensions?
├─ Overview and concepts -> how-to/extensions-overview.md
├─ Define extensions in config -> configuration/neutralino.config.json.md (extensions)
├─ Enable extensions -> configuration/neutralino.config.json.md (enableExtensions)
├─ Dispatch to extension -> api/extensions.md (dispatch)
├─ Extension receives messages -> how-to/extensions-overview.md (WebSocket protocol)
└─ Extension calls native API -> how-to/extensions-overview.md (app.broadcast)

"I need app lifecycle control"

Lifecycle?
├─ Exit app -> api/app.md (exit)
├─ Kill process (force) -> api/app.md (killProcess)
├─ Restart app -> api/app.md (restartProcess)
├─ Get app config -> api/app.md (getConfig)
├─ Broadcast to all instances -> api/app.md (broadcast)
├─ Read/write stdin/stdout -> api/app.md (readProcessInput, writeProcessOutput)
└─ Initialize client -> api/init.md (init)

"Which mode should I use?"

Application mode?
├─ Desktop app with native window -> window mode (default)
├─ Web app with native features -> browser mode
├─ Background server/API -> cloud mode
├─ Chrome app style -> chrome mode
└─ Details -> configuration/modes.md

"I need security configuration"

Security?
├─ Restrict API access -> configuration/neutralino.config.json.md (nativeAllowList, nativeBlockList)
├─ Token security -> configuration/neutralino.config.json.md (tokenSecurity)
├─ Export auth info -> configuration/neutralino.config.json.md (exportAuthInfo)
└─ Global variables -> api/global-variables.md

"I need to integrate with frontend frameworks"

Frontend integration?
├─ React/Vue/Angular -> getting-started/using-frontend-libraries.md
├─ Import client lib -> npm: @neutralinojs/lib
├─ CLI frontend support -> configuration/neutralino.config.json.md (cli.frontendLibrary)
└─ HMR/DevTools -> cli/neu-cli.md (neu run with dev server)

Product Index

API Namespaces

Configuration

CLI

Getting Started

How-To

Distribution

Key Patterns

File Operations

// Read/write text files
let content = await Neutralino.filesystem.readFile('./data.txt');
await Neutralino.filesystem.writeFile('./output.txt', 'Hello World');

// Binary file operations
let buffer = await Neutralino.filesystem.readBinaryFile('./image.png');
let rawBin = new ArrayBuffer(1);
let view = new Uint8Array(rawBin);
view[0] = 64;
await Neutralino.filesystem.writeBinaryFile('./data.bin', rawBin);

// File stats and existence check
try {
  let stats = await Neutralino.filesystem.getStats('./file.txt');
  console.log(`Size: ${stats.size}, IsFile: ${stats.isFile}`);
} catch(err) {
  if (err.code === 'NE_FS_NOPATHE') {
    console.log('File does not exist');
  }
}

Process Management

// Execute command and get output
let result = await Neutralino.os.execCommand('python --version');
console.log(result.stdOut);

// Spawn background process with event monitoring
let proc = await Neutralino.os.spawnProcess('ping google.com');

Neutralino.events.on('spawnedProcess', (evt) => {
  if (proc.id === evt.detail.id) {
    switch(evt.detail.action) {
      case 'stdOut':
        console.log(evt.detail.data);
        break;
      case 'stdErr':
        console.error(evt.detail.data);
        break;
      case 'exit':
        console.log(`Exit code: ${evt.detail.data}`);
        break;
    }
  }
});

// Send input to spawned process
await Neutralino.os.updateSpawnedProcess(proc.id, 'stdIn', 'input data');
await Neutralino.os.updateSpawnedProcess(proc.id, 'stdInEnd');

System Tray Integration

// Set up tray with menu
let tray = {
  icon: '/resources/icons/tray.png',
  menuItems: [
    {id: "show", text: "Show Window"},
    {text: "-"}, // Separator
    {id: "quit", text: "Quit"}
  ]
};

await Neutralino.os.setTray(tray);

// Handle tray menu clicks
Neutralino.events.on('trayMenuItemClicked', (evt) => {
  switch(evt.detail.id) {
    case 'show':
      // Show window logic
      break;
    case 'quit':
      Neutralino.app.exit();
      break;
  }
});

Clipboard Operations

// Text clipboard
await Neutralino.clipboard.writeText('Hello World');
let text = await Neutralino.clipboard.readText();

// HTML clipboard
await Neutralino.clipboard.writeHTML('<p style="color:red;">Formatted</p>');
let html = await Neutralino.clipboard.readHTML();

// Check clipboard format
let format = await Neutralino.clipboard.getFormat();

System Information

// CPU information
let cpu = await Neutralino.computer.getCPUInfo();
console.log(`CPU: ${cpu.model}, Cores: ${cpu.physicalCores}`);

// Display information
let displays = await Neutralino.computer.getDisplays();
displays.forEach(display => {
  console.log(`Display ${display.id}: ${display.resolution.width}x${display.resolution.height}`);
});

// Architecture and OS
let arch = await Neutralino.computer.getArch();
let username = await Neutralino.os.getEnv(NL_OS === 'Windows' ? 'USERNAME' : 'USER');

Notifications

// Basic notification
await Neutralino.os.showNotification('Title', 'Message content');

// Notification with icon type
await Neutralino.os.showNotification('Error', 'Something went wrong', 'ERROR');
// Icon types: INFO, WARNING, ERROR, QUESTION

Common Mistakes

• Missing await on async calls — All native APIs return promises
• Not checking file existence — Use getStats() to verify files exist before operations
• Forgetting process cleanup — Always handle spawned process exit events
• Invalid tray icon paths — Use /resources/ prefix for bundled assets
• Missing error handling — Wrap native API calls in try-catch blocks

Resources

Repository: https://github.com/neutralinojs/neutralinojs Documentation: https://neutralino.js.org Client Library (NPM): https://www.npmjs.com/package/@neutralinojs/lib CLI (NPM): https://www.npmjs.com/package/@neutralinojs/neu Discussions: https://github.com/neutralinojs/neutralinojs/discussions