Application API

Overview

The Application is the core of your Wails app. It manages windows, services, events, and provides access to all platform features.

Creating an Application

import "github.com/wailsapp/wails/v3/pkg/application"

app := application.New(application.Options{
    Name:        "My App",
    Description: "My awesome application",
    Services: []application.Service{
        application.NewService(&MyService{}),
    },
})

Core Methods

Run()

Starts the application event loop.

func (a *App) Run() error

Example:

err := app.Run()
if err != nil {
    log.Fatal(err)
}

Returns: Error if startup fails

Quit()

Gracefully shuts down the application.

func (a *App) Quit()

Example:

// In a menu handler
menu.Add("Quit").OnClick(func(ctx *application.Context) {
    app.Quit()
})

Config()

Returns the application configuration.

func (a *App) Config() Options

Example:

config := app.Config()
fmt.Println("App name:", config.Name)

Window Management

app.Window.New()

Creates a new webview window with default options.

func (wm *WindowManager) New() *WebviewWindow

Example:

window := app.Window.New()
window.Show()

app.Window.NewWithOptions()

Creates a new webview window with custom options.

func (wm *WindowManager) NewWithOptions(options WebviewWindowOptions) *WebviewWindow

Example:

window := app.Window.NewWithOptions(application.WebviewWindowOptions{
    Title:  "My Window",
    Width:  800,
    Height: 600,
    BackgroundColour: application.NewRGB(255, 255, 255),
})

app.Window.GetByName()

Gets a window by its name. Returns the window and whether it was found.

func (wm *WindowManager) GetByName(name string) (Window, bool)

Example:

if window, ok := app.Window.GetByName("main"); ok {
    window.Show()
}

app.Window.GetAll()

Returns all application windows.

func (wm *WindowManager) GetAll() []Window

Example:

windows := app.Window.GetAll()
for _, window := range windows {
    fmt.Println("Window:", window.Name())
}

Managers

The Application provides access to various managers through properties:

app.Window       // Window management
app.Menu         // Menu management
app.Dialog       // Dialog management
app.Event        // Event management
app.Clipboard    // Clipboard operations
app.Screen       // Screen information
app.SystemTray   // System tray
app.Browser      // Browser operations
app.Env          // Environment variables
app.ContextMenu  // Context-menu management
app.KeyBinding   // Global keyboard shortcuts
app.Logger       // *slog.Logger

Example Usage

// Create window
window := app.Window.New()

// Show dialog
app.Dialog.Info().SetMessage("Hello!").Show()

// Copy to clipboard
app.Clipboard.SetText("Copied text")

// Get screens
screens := app.Screen.GetAll()

Service Management

RegisterService()

Registers a service with the application.

func (a *App) RegisterService(service Service)

RegisterService returns nothing; service initialisation errors surface via ServiceStartup failures during app.Run().

Example:

type MyService struct {
    app *application.App
}

func NewMyService(app *application.App) *MyService {
    return &MyService{app: app}
}

// Register after app creation
app.RegisterService(application.NewService(NewMyService(app)))

Event Management

app.Event.Emit()

Emits a custom event. Returns true if a hook cancelled the emit.

func (em *EventManager) Emit(name string, data ...any) bool

Example:

// Emit event with data
app.Event.Emit("user-logged-in", map[string]interface{}{
    "username": "john",
    "timestamp": time.Now(),
})

app.Event.On()

Listens for custom events. Returns an unsubscribe func().

func (em *EventManager) On(name string, callback func(*CustomEvent)) func()

Example:

app.Event.On("user-logged-in", func(e *application.CustomEvent) {
    data := e.Data.(map[string]interface{})
    username := data["username"].(string)
    fmt.Println("User logged in:", username)
})

app.Event.OnApplicationEvent()

Listens for application lifecycle events. The eventType parameter is events.ApplicationEventType (from the events package).

func (em *EventManager) OnApplicationEvent(
    eventType events.ApplicationEventType,
    callback func(*ApplicationEvent),
) func()

Example:

import "github.com/wailsapp/wails/v3/pkg/events"

// Listen for app-started
app.Event.OnApplicationEvent(events.Common.ApplicationStarted, func(e *application.ApplicationEvent) {
    fmt.Println("Application started")
})

// Application shutdown is NOT an event constant; register cleanup via:
app.OnShutdown(func() {
    fmt.Println("Application shutting down")
})

Dialog Methods

Dialogs are accessed through the app.Dialog manager. See Dialogs API for complete reference.

Message Dialogs

// Information dialog
app.Dialog.Info().
    SetTitle("Success").
    SetMessage("Operation completed!").
    Show()

// Error dialog
app.Dialog.Error().
    SetTitle("Error").
    SetMessage("Something went wrong.").
    Show()

// Warning dialog
app.Dialog.Warning().
    SetTitle("Warning").
    SetMessage("This action cannot be undone.").
    Show()

Question Dialogs

Question dialogs use button callbacks to handle user responses:

dialog := app.Dialog.Question().
    SetTitle("Confirm").
    SetMessage("Continue?")

yes := dialog.AddButton("Yes")
yes.OnClick(func() {
    // Handle yes
})

no := dialog.AddButton("No")
no.OnClick(func() {
    // Handle no
})

dialog.SetDefaultButton(yes)
dialog.SetCancelButton(no)
dialog.Show()

File Dialogs

// Open file dialog
path, err := app.Dialog.OpenFile().
    SetTitle("Select File").
    AddFilter("Images", "*.png;*.jpg").
    PromptForSingleSelection()

// Save file dialog
path, err := app.Dialog.SaveFile().
    SetTitle("Save File").
    SetFilename("document.pdf").
    AddFilter("PDF", "*.pdf").
    PromptForSingleSelection()

// Folder selection (use OpenFile with directory options)
path, err := app.Dialog.OpenFile().
    SetTitle("Select Folder").
    CanChooseDirectories(true).
    CanChooseFiles(false).
    PromptForSingleSelection()

Logger

The application provides a structured logger:

app.Logger.Info("Message", "key", "value")
app.Logger.Error("Error occurred", "error", err)
app.Logger.Debug("Debug info")
app.Logger.Warn("Warning message")

Example:

func (s *MyService) ProcessData(data string) error {
    s.app.Logger.Info("Processing data", "length", len(data))
    
    if err := process(data); err != nil {
        s.app.Logger.Error("Processing failed", "error", err)
        return err
    }
    
    s.app.Logger.Info("Processing complete")
    return nil
}

Raw Message Handling

For applications that need direct, low-level control over frontend-to-backend communication, Wails provides the RawMessageHandler option. This bypasses the standard binding system.

RawMessageHandler

RawMessageHandler is a field on application.Options, not a method. The runtime invokes it for every raw message sent from the frontend via System.invoke().

type Options struct {
    // ... other fields ...
    RawMessageHandler func(window Window, message string, originInfo *OriginInfo)
}

OriginInfo carries Origin, TopOrigin, and IsMainFrame (platforms populate different subsets — see the Raw Messages Guide for the per-platform matrix).

Example:

app := application.New(application.Options{
    Name: "My App",
    RawMessageHandler: func(window application.Window, message string, originInfo *application.OriginInfo) {
        // Handle the raw message
        fmt.Printf("Received from %s (%s): %s\n", window.Name(), originInfo.Origin, message)

        // You can respond using events
        window.EmitEvent("response", processMessage(message))
    },
})

For more details, see the Raw Messages Guide.

Platform-Specific Options

Windows Options

Configure Windows-specific behavior at the application level:

app := application.New(application.Options{
    Name: "My App",
    Windows: application.WindowsOptions{
        // WebView2 browser flags (apply to ALL windows)
        EnabledFeatures:       []string{"msWebView2EnableDraggableRegions"},
        DisabledFeatures:      []string{"msExperimentalFeature"},
        AdditionalBrowserArgs: []string{"--remote-debugging-port=9222"},

        // Other Windows options
        WndClass:                      "MyAppClass",
        WebviewUserDataPath:           "",  // Default: %APPDATA%\[BinaryName.exe]
        WebviewBrowserPath:            "",  // Default: system WebView2
        DisableQuitOnLastWindowClosed: false,
    },
})

Browser Flags:

EnabledFeatures - WebView2 feature flags to enable
DisabledFeatures - WebView2 feature flags to disable
AdditionalBrowserArgs - Chromium command-line arguments

See Window Options - Application-Level Windows Options for detailed documentation.

Mac Options

app := application.New(application.Options{
    Name: "My App",
    Mac: application.MacOptions{
        ActivationPolicy: application.ActivationPolicyRegular,
        ApplicationShouldTerminateAfterLastWindowClosed: true,
    },
})

Linux Options

app := application.New(application.Options{
    Name: "My App",
    Linux: application.LinuxOptions{
        ProgramName:                   "my-app",
        DisableQuitOnLastWindowClosed: false,
    },
})

Complete Application Example

package main

import (
    "github.com/wailsapp/wails/v3/pkg/application"
)

func main() {
    app := application.New(application.Options{
        Name:        "My Application",
        Description: "A demo application",
        Mac: application.MacOptions{
            ApplicationShouldTerminateAfterLastWindowClosed: true,
        },
    })

    // Create main window
    window := app.Window.NewWithOptions(application.WebviewWindowOptions{
        Title:            "My App",
        Width:            1024,
        Height:           768,
        MinWidth:         800,
        MinHeight:        600,
        BackgroundColour: application.NewRGB(255, 255, 255),
        URL:              "http://wails.localhost/",
    })

    window.Center()
    window.Show()

    app.Run()
}