eXeMeL

A desktop XML editor for Windows, built for developers who work with XML daily. eXeMeL reads XML from the clipboard on launch, cleans and formats it automatically, and provides syntax-highlighted editing with an integrated XPath authoring tool.

Features

• Clipboard-first workflow — paste XML (or press F5) and it's instantly cleaned, decoded, and formatted
• XML cleaning pipeline — automatically handles URL-encoded XML, Visual Studio debug output, escaped quotes, whitespace, and XML fragments
• Syntax highlighting — five built-in color schemes (Bright, Earthy, Ethereal, Blue, Solarized Dark) with light and dark themes
• XPath utility — interactive XML tree view with XPath expression evaluation, element highlighting, and XPath generation via right-click
• Document snapshots — save and navigate between editing checkpoints
• Encoded XML extraction — right-click to decode and "delve into" HTML-encoded XML inside attributes
• Code folding — collapse/expand XML elements by level (Alt+0-9)
• File support — open, save, and drag-drop XML files
• Single executable — no installer required, just download and run

Getting Started

Download

Download either the intallable or stand-alone version of eXeMeL from the latest release.

Build from source

Requires .NET 9 SDK.

cd src\eXeMeL
dotnet build eXeMeL\eXeMeL.csproj
dotnet run --project eXeMeL\eXeMeL.csproj

Publish single-file executable

cd src\eXeMeL
dotnet publish eXeMeL\eXeMeL.csproj -c Release -r win-x64 --self-contained true /p:PublishSingleFile=true /p:IncludeNativeLibrariesForSelfExtract=true /p:EnableCompressionInSingleFile=true

Output: eXeMeL\bin\Release\net9.0-windows\win-x64\publish\eXeMeL.exe

Run tests

cd src\eXeMeL
dotnet test eXeMeL.Tests\eXeMeL.Tests.csproj

Keyboard Shortcuts

Shortcut	Action
F5	Refresh — read clipboard, clean, and display XML
F2	Toggle between Editor and XPath Utility views
Ctrl+F	Find text
Ctrl+S	Save file
Ctrl+O	Open file
Alt+0-9	Fold XML elements at level
Alt+Shift+0-9	Unfold XML elements at level
Alt+-	Fold all
Alt+Shift+-	Unfold all
Escape	Return focus to editor

Settings

User settings are stored at %LOCALAPPDATA%\eXeMeL2\settings.json. If upgrading from an older version that stored settings in the Windows Registry (HKCU\Software\eXeMeL), they are migrated automatically on first launch.

Technology Stack

• Runtime: .NET 9 (Windows)
• UI Framework: WPF with MaterialDesignInXamlToolkit
• Text Editor: AvalonEdit 6.3
• MVVM: CommunityToolkit.Mvvm 8.4
• Behaviors: Microsoft.Xaml.Behaviors.Wpf

Migration History

This application was originally built circa 2013 on .NET Framework 4.5. In April 2026 it was migrated to .NET 9 with the following changes:

Framework and project system

• .NET Framework 4.5 to .NET 9 (net9.0-windows)
• Old-style .csproj to SDK-style
• packages.config NuGet to PackageReference

Library replacements

Before	After	Reason
MvvmLight 4.1	CommunityToolkit.Mvvm 8.4	MvvmLight unmaintained since 2018
MvvmFoundation.Wpf 1.0	In-tree PropertyObserver	Unmaintained since 2012
CommonServiceLocator 1.0	Microsoft.Extensions.DependencyInjection 9.0	Standard .NET DI
MahApps.Metro 0.12.1	MaterialDesignInXamlToolkit 5.1 + WindowChrome	No .NET 9 support for MahApps 0.x
AvalonEdit 4.4	AvalonEdit 6.3	Modern .NET support (zero breaking changes)
Microsoft.Xaml.Behaviors.Wpf 1.1.19	1.1.77	Version bump

Deployment

• ClickOnce installer removed (signing keys, manifests, bootstrapper config)
• Single self-contained executable via dotnet publish (~74 MB)
• Command-line file argument replaces ClickOnce activation

Settings storage

• Windows Registry (HKCU\Software\eXeMeL) replaced with local JSON file (%LOCALAPPDATA%\eXeMeL2\settings.json)
• Automatic one-time migration from Registry on first run
• System.Text.Json replaces DataContractJsonSerializer

Test coverage

• 116 xUnit tests added (103 passing, 13 skipped pending UI stabilization)
• XML cleaning pipeline, settings serialization, XPath utility, and behavioral workflow tests

License

Originally published at github.com/Grandpappy/eXeMeL.