Markdown++

Markdown++ is a native x64 Notepad++ plugin for live Markdown preview.

It renders Markdown in a dockable WebView2 panel, uses cmark-gfm for GitHub-flavored Markdown, and bundles Mermaid support for offline diagrams.

Features

• Dockable Notepad++ preview panel.
• Auto-open for common Markdown extensions.
• GitHub-flavored Markdown rendering through cmark-gfm.
• Bundled Mermaid diagram rendering with visible inline errors.
• Local image and SVG resolution through a document virtual host.
• Local Markdown links open or switch files in Notepad++.
• External links open through the default browser path.
• Fragment links scroll both the preview and the editor.
• Source-line-based editor/preview scroll sync.
• Menu-only persisted settings for auto-open, scroll sync, Mermaid rendering, and preview update delay.
• Copy rendered HTML to the clipboard.
• Export standalone HTML.
• Export standalone PDF.
• Open the WebView2 system print dialog.

Mermaid Diagrams

Markdown++ strictly parses Mermaid diagrams to ensure proper rendering and styling.

1. Fenced Code Blocks: Always wrap your graph inside an explicit Markdown code block tagged with mermaid:

   ```mermaid
   graph TD
       A[Submit] --> B[Review]

2. Subgraph Identifiers: A strict parsing engine requires all subgraphs to use explicit, alphanumeric alias identifiers. Do not attempt to style anonymous subgraphs or use full textual descriptions as the direct subgraph ID.

   ❌ Incorrect (Will fail to style):

   subgraph "Security Review Stage"
       direction LR
   end
   style "Security Review Stage" fill:#fff
   

   Loading

   ✅ Correct (Use aliases):

   subgraph STAGE2 ["Security Review Stage"]
       direction LR
   end
   style STAGE2 fill:#fff
   

   Loading

   ✅ Correct (Blank Titles): (If you want a subgraph without a visual title, alias it and pass a single space)

   subgraph GATE1 [" "]
       direction LR
       G1[Gate]
   end
   

   Loading

Requirements

• Windows.
• Notepad++ x64.
• Microsoft Edge WebView2 Evergreen Runtime.
• Visual Studio 2026 v18 with MSVC v145 and a Windows 10/11 SDK for building.
• CMake 4.2 or newer for the Visual Studio 18 2026 generator.

The WebView2 Evergreen Runtime is a user-machine runtime dependency. The plugin detects a missing runtime and shows install guidance in the preview panel.

Build

Install repo-local build dependencies:

python .\tools\install-native-deps.py

Build and package Release:

powershell -ExecutionPolicy Bypass -File .\tools\build-native.ps1 -Configuration Release -Package

Build, package, and install:

powershell -ExecutionPolicy Bypass -File .\tools\build-native.ps1 -Configuration Release -Install

Close Notepad++ before installing so MarkdownPlusPlus.dll is not locked. If Notepad++ is installed under C:\Program Files, run PowerShell as Administrator if Windows denies the copy.

More details are in BUILDING_NATIVE.md.

Package Layout

The ready-to-copy plugin folder is emitted under:

build/cmake/vs2026-x64/package/Release/MarkdownPlusPlus/

Expected package contents:

MarkdownPlusPlus/
  MarkdownPlusPlus.dll
  assets/
    preview.css
    preview.js
    mermaid/
      mermaid.min.js
      README.md

The package contains runtime files only. Build dependencies such as WebView2 SDK files, NuGet CLI, and cmark-gfm source are recreated locally by tools/install-native-deps.py and are not part of the plugin package.

Smoke Test

After install, run:

MarkdownPlusPlus.Native/SMOKE_CHECKLIST.md

Primary manual fixtures:

smoke-tests/markdownplusplus-smoke.md
smoke-tests/smoke-test.md

Repository Layout

MarkdownPlusPlus.Native/     Native plugin source, assets, and native docs
smoke-tests/                 Manual smoke-test Markdown fixtures
tools/                       Dependency, build, and install helpers
BUILDING_NATIVE.md           Full native build instructions
CMakeLists.txt               Native CMake entry point
CMakePresets.json            Visual Studio 2026 x64 presets

Dependencies And Notices

Markdown++ is released under the MIT license in LICENSE.md.

Native dependency setup and third-party notice guidance are documented in MarkdownPlusPlus.Native/DEPENDENCIES.md.