Why Hermes?

The Problem

Building desktop apps with .NET has historically meant choosing between two fundamentally different approaches:

Native Control Frameworks

These render UI using platform widgets or custom drawing:

• WPF — Mature and powerful, but Windows-only with no cross-platform path
• WinForms — Simple and fast, but dated and Windows-only
• Avalonia — True cross-platform XAML, but requires learning a new UI paradigm
• MAUI — Microsoft-backed cross-platform, but heavy abstraction with inconsistent behavior across platforms

WebView-Based Frameworks

These render web content (HTML/CSS/JS) inside a native shell:

• Electron — Great ecosystem with full native menu support, but large bundles (~150MB+) and high memory usage
• Photino — Lightweight .NET wrapper, but limited native menu support and complex C++ codebase
• Tauri — Rust-based and efficient with native menus, but requires Rust for native extensions

For .NET developers wanting a lightweight WebView framework with native menu support, the options are limited. Photino is the closest, but its menu capabilities are basic and its C++ codebase makes contributions difficult.

Hermes' Approach

Hermes takes a different approach:

1. Minimal Native Code

Framework	Lines of Code
Hermes	~3,800 (mostly C#)
Photino	~12,300
Electron	Millions

Less code means fewer bugs, easier maintenance, and faster builds.

2. Native Menus First

Hermes was designed from the ground up for applications that need:

• Dynamic menu modification at runtime
• Plugin loading that adds menu items
• Accelerator keys that work natively
• Platform-appropriate behavior (macOS dock menus, Windows system menus)

// Add a menu item at runtime
menuBar["Tools"].InsertItem(
    afterId: "tools.options",
    label: "My Plugin",
    commandId: "plugins.myplugin.open"
);

3. Modern .NET

Hermes targets .NET 10+ and uses:

• LibraryImport with source generators (AOT-ready)
• file-scoped types and required members
• Span<T> and Memory<T> throughout
• Primary constructors where appropriate

4. Pure C# Where Possible

• Windows: Entirely C# using Microsoft.Web.WebView2 and CsWin32
• Linux: Entirely C# using GtkSharp
• macOS: Thin Objective-C wrapper (~500 LOC) for Cocoa APIs

Licensing

Hermes uses the Elastic License 2.0, which means:

• Free for non-commercial, educational, open source, and small businesses (<$1M revenue)
• $695/app/year for commercial use by organizations >$1M revenue

See Licensing for full details.

When to Use Hermes

Hermes is ideal for:

• IDEs and code editors
• Developer tools
• Desktop utilities with plugin systems
• Any app needing native menu integration

Consider alternatives if you need:

• Mobile support (use MAUI or Flutter)
• Extremely small binary size (consider Tauri with Rust)
• Legacy .NET Framework support (use WinForms or WPF)