MDViewer Documentation

🚀 Quick Start

After first launch

• File associations — right-click any .md file to see "Open with MDViewer" (MSI install only)
• Recent files — File menu tracks your recently opened documents
• Settings persist — window size, zoom level, and preferences are saved automatically to %LocalAppData%\MDViewer\settings.json
• Repository detection — MDViewer walks up the directory tree to find your documentation root automatically

💿 Installation

Portable ZIP

1. Download MDViewer-vX.X.X-Portable.zip from the Downloads page
2. Extract to any folder (e.g. C:\Tools\MDViewer\)
3. Run MDViewer.exe — no install or admin rights required

Install script

1. Download Install-MDViewer-vX.X.X.bat
2. Right-click → Run as administrator
3. The script downloads the MSI, installs it silently, and sets up file associations

Silent / enterprise MSI install

# PowerShell — download and install silently
$repo = "MDViewer-App/mdviewer.app"
$rel  = Invoke-RestMethod "https://api.github.com/repos/$repo/releases/latest"
$msi  = ($rel.assets | Where-Object { $_.name -like "*Setup.msi" }).browser_download_url
$out  = "$env:TEMP\MDViewer-Setup.msi"
Invoke-WebRequest $msi -OutFile $out
Start-Process msiexec.exe -ArgumentList "/i `"$out`" /quiet /norestart" -Wait
Remove-Item $out

Verifying downloads

# PowerShell SHA256 check
Get-FileHash .\MDViewer-vX.X.X-Portable.zip -Algorithm SHA256
# Compare against checksums-vX.X.X.txt on the release page

✨ Feature Overview

🧭 Navigation System

Repository detection

When you open a file, MDViewer walks up the directory tree until it finds a .git folder or a directory with a high density of .md files. That directory becomes the navigation root. The breadcrumb header and footer are then generated relative to that root.

Link resolution

Image resolution

Images are served via a file:// base URL set to the file's directory, so relative paths like ![Diagram](./images/diagram.png) always resolve correctly regardless of where MDViewer is installed.

✏️ Built-in Editor

Opening the editor

• Ctrl+E from the viewer
• Tools menu → Open Editor

File operations

External editor

1. Go to Settings → External Editor
2. Set the path to your preferred editor (e.g. C:\Program Files\Microsoft VS Code\Code.exe)
3. Press Ctrl+Shift+E in the viewer to open the current file in that editor

📄 Export

PDF export

Word export

# If Word export fails, run this in PowerShell (as admin)
Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

🏢 Enterprise Features

Documentation Hub

Open via Ctrl+D or Tools → Documentation Hub. Designed for teams managing large documentation sets across departments.

Deployment

; Pre-configure external editor for all users
[HKEY_LOCAL_MACHINE\SOFTWARE\MDViewer]
"ExternalEditor"="C:\\Program Files\\Microsoft VS Code\\Code.exe"

🔌 Embeddable Controls Library

New in v1.7.0. MarkdownViewer.Controls packages the full MDViewer rendering engine as a WinForms UserControl you can drop into any .NET Windows desktop application — no separate process, no WebSocket server, no infrastructure.

¹ PDF export requires .NET 6+. On net48, ExportPdfAsync() throws PlatformNotSupportedException with a clear upgrade message.

Quick start — C#

var viewer = new MarkdownViewer.Controls.MarkdownViewerControl();
viewer.Dock = DockStyle.Fill;
this.Controls.Add(viewer);
viewer.LoadFile(@"C:\docs\README.md");

Quick start — VB.NET

Dim viewer As New MarkdownViewer.Controls.MarkdownViewerControl()
viewer.Dock = DockStyle.Fill
Me.Controls.Add(viewer)
viewer.LoadFile("C:\docs\README.md")

Loading inline Markdown

// Load from string instead of file
viewer.LoadMarkdown("# Hello World\n\nThis is **inline** content.", baseDirectory: @"C:\docs");

Listening to navigation events

viewer.FileNavigated += (s, path) => {
    titleBar.Text = Path.GetFileName(path);
};
viewer.CanNavigateBackChanged += (s, canGoBack) => {
    backButton.Enabled = canGoBack;
};

⌨️ Keyboard Shortcuts

Viewer

Editor window

🔧 Troubleshooting

Diagnostic mode

# Run built-in diagnostics from the command line
MDViewer.exe --test

This runs checks for .NET runtime availability, Markdig parsing, WebView2 presence, and filesystem access. Output is shown in the console.

%LocalAppData%\MDViewer\settings.json

⚙️ Advanced Usage

Command-line interface

# Open a specific file
MDViewer.exe "C:\Docs\README.md"

# Run diagnostics
MDViewer.exe --test

# Convert Markdown to PDF (headless)
MDViewer.exe convert input.md pdf output.pdf

# Convert Markdown to HTML
MDViewer.exe convert input.md html output.html

# Show version
MDViewer.exe --version

Settings file

User settings are stored at %LocalAppData%\MDViewer\settings.json. You can pre-configure them for deployment:

{
  "ZoomFactor": 1.0,
  "ExternalEditor": "C:\\Program Files\\Microsoft VS Code\\Code.exe",
  "Theme": "GitHub",
  "WindowWidth": 1200,
  "WindowHeight": 800
}

Custom CSS themes

/* Place in %LocalAppData%\MDViewer\Themes\custom.css */
body {
    font-family: 'Georgia', serif;
    background: #fafaf8;
    color: #2c2c2c;
}

h1, h2, h3 {
    color: #1a1a6e;
    border-bottom: 1px solid #ddd;
}

code {
    background: #f0f0f0;
    color: #c0392b;
}

Git integration notes

MDViewer detects .git folders to set the navigation root and resolve absolute image paths. If your repository has a non-standard structure (monorepo, sparse checkout), you can place a .mdviewer-root marker file in the directory you want treated as the documentation root.

💬 Support