Hermes

A modern, AOT-compatible native desktop framework for .NET 10.

Overview

Hermes is a cross-platform desktop framework that enables .NET developers to create native desktop applications with web-based UIs. It provides native windows, menus, dialogs, and WebView integration across Windows, macOS, and Linux.

Designed for .NET 10 and modern development workflows, Hermes prioritizes AOT compatibility, minimal native code, and runtime performance. Unlike frameworks that rely on large C++ codebases, Hermes uses pure C# on Windows (via CsWin32 source generators) and thin native shims on macOS and Linux, totaling approximately 4,900 lines of native code.

Features

• Native Windows and WebView Platform-native windows with embedded WebView2 (Windows), WebKitGTK (Linux), and WKWebView (macOS)
• Native Menus Full menu bar support with keyboard accelerators and runtime modification for plugin systems
• Context Menus Native right-click menus with screen coordinate positioning
• File Dialogs Native open, save, and folder selection dialogs with file filters
• AOT Compatible,Designed for Native AOT from day one using LibraryImport instead of DllImport
• Blazor Integration First-class support for Blazor applications via Hermes.Blazor
• Cross-Platform Single codebase targeting Windows, macOS, and Linux
• Minimal Dependencies Pure C# on Windows; thin native layers only where required

Platform Support

Platform	Runtime	WebView	Status
Windows 10/11	.NET 10	WebView2	Supported
macOS 12+	.NET 10	WKWebView	Supported
Linux (x64)	.NET 10	WebKitGTK 4.x	Supported

Getting Started

Installation

dotnet add package Mythetech.Hermes

For Blazor applications:

dotnet add package Mythetech.Hermes.Blazor

Basic Example

using Hermes;

var window = new HermesWindow()
    .SetTitle("My Application")
    .SetSize(1024, 768)
    .Center()
    .Load("https://example.com");

window.WaitForClose();

Blazor Example

using Hermes;
using Hermes.Blazor;

HermesWindow.Prewarm();

var builder = HermesBlazorAppBuilder.CreateDefault(args);

builder.ConfigureWindow(options =>
{
    options.Title = "My Blazor App";
    options.Width = 1024;
    options.Height = 768;
    options.CenterOnScreen = true;
});

builder.RootComponents.Add<App>("#app");

var app = builder.Build();
app.Run();

Native Menus

Hermes provides a fluent API for building native menus with full support for runtime modification, enabling dynamic plugin loading scenarios.

// Build menus with fluent API
window.MenuBar
    .AddMenu("File", file =>
    {
        file.AddItem("New", "file.new", item => item.WithAccelerator("Ctrl+N"))
            .AddItem("Open...", "file.open", item => item.WithAccelerator("Ctrl+O"))
            .AddSeparator()
            .AddItem("Save", "file.save", item => item.WithAccelerator("Ctrl+S"))
            .AddItem("Exit", "file.exit");
    })
    .AddMenu("Edit", edit =>
    {
        edit.AddItem("Undo", "edit.undo", item => item.WithAccelerator("Ctrl+Z"))
            .AddItem("Redo", "edit.redo", item => item.WithAccelerator("Ctrl+Y"))
            .AddSeparator()
            .AddItem("Cut", "edit.cut", item => item.WithAccelerator("Ctrl+X"))
            .AddItem("Copy", "edit.copy", item => item.WithAccelerator("Ctrl+C"))
            .AddItem("Paste", "edit.paste", item => item.WithAccelerator("Ctrl+V"));
    });

// Handle menu clicks
window.MenuBar.ItemClicked += itemId =>
{
    if (itemId == "file.exit")
        window.Close();
};

// Runtime modification for plugins
window.MenuBar.AddMenu("Plugins", plugins =>
{
    plugins.AddItem("My Plugin", "plugins.myplugin");
});

Accelerators automatically translate between platforms, Ctrl+S on Windows/Linux becomes Cmd+S on macOS.

Architecture

Hermes minimizes native code by leveraging platform-specific .NET capabilities:

Platform	Approach	Native Code
Windows	CsWin32 source generators + WebView2 NuGet	None
macOS	Thin Objective-C shim with LibraryImport	~3,100 LOC
Linux	Thin C shim with LibraryImport	~1,800 LOC

This architecture provides:

• Easier maintenance, Most logic lives in C#, not platform-specific native code
• AOT compatibility, LibraryImport generates marshalling code at compile time
• Reduced build complexity, No C++ toolchain required on Windows

For detailed technical information, see ARCHITECTURE.md.

Packages

Package	Description
Mythetech.Hermes	Core framework
Mythetech.Hermes.Blazor	Blazor integration

Documentation

• Architecture Overview: Technical design and platform strategy
• Platform Differences: Cross-platform behavior notes
• Roadmap: Planned features and enhancements

License

Hermes is source-available under the Elastic License 2.0.

Free for: non-commercial use, educational use, open source projects, and commercial use under $1M annual revenue. See COMMERCIAL.md for details.