rumdl - Markdown Linter for VS Code

A lightning-fast Markdown linter for VS Code powered by rumdl, a Rust-based linter with 97.2% markdownlint compatibility and 5x performance improvement.

Features

✅ Real-time linting with 50+ rules and precise column highlighting ✅ One-click auto-fixes for common issues ✅ 5x faster than markdownlint ✅ Markdownlint compatibility ✅ Zero configuration required ✅ Workspace-wide linting support ✅ Custom rule configuration ✅ Status bar integration ✅ Precise error positioning with improved column highlighting (rumdl 0.0.81+) ✅ Bundled rumdl binary - no separate installation required ✅ Cross-platform support with optimized binaries for all platforms

Installation

From VS Code

1. Install the extension from the VS Code Marketplace
2. That's it! rumdl is bundled with the extension - no additional setup required

From Cursor / VSCodium / Other VS Code Forks

1. Install the extension from Open VSX Registry
2. That's it! The extension works the same in all VS Code-compatible editors

The extension includes optimized rumdl binaries for all supported platforms:

• Windows (x64)
• macOS (Intel & Apple Silicon)
• Linux (x64 & ARM64)

Manual Installation (Optional)

If you prefer to use your own rumdl installation:

1. Install rumdl using one of these methods:

   # Using Cargo (Rust)
   cargo install rumdl
   
   # Using pip (Python)
   pip install rumdl
   
   # Download binary from GitHub releases
   # See: https://github.com/rvben/rumdl/releases
   

2. Configure the path in VS Code settings:

   {
     "rumdl.server.path": "/path/to/your/rumdl"
   }
   

Quick Start

1. Install the extension from the VS Code Marketplace
2. Install rumdl (if not already installed):

   # Using cargo
   cargo install rumdl
   
   # Using homebrew (macOS)
   brew install rumdl
   
   # Using npm
   npm install -g rumdl
   

3. Open a Markdown file - linting starts automatically!

Screenshots

Real-time Diagnostics

Quick Fixes

Status Bar Integration

Commands

Access these commands via the Command Palette (Cmd/Ctrl + Shift + P):

• rumdl: Fix All - Apply all available auto-fixes to the current document
• rumdl: Restart Server - Restart the rumdl language server
• rumdl: Show Client Logs - View extension logs in the output panel
• rumdl: Show Server Logs - View server logs in the output panel
• rumdl: Check Extension Status - Display extension status and configuration
• rumdl: Test Configuration Discovery - Debug configuration file discovery and test rumdl settings

Fix on Save

There are two ways to automatically fix Markdown issues when saving files:

Option 1: editor.codeActionsOnSave (Recommended)

This is the standard VS Code mechanism, used by ESLint, Ruff, and other linters. It gives you fine-grained control:

{
  "editor.codeActionsOnSave": {
    "source.fixAll.rumdl": "explicit"
  }
}

Use "explicit" to only fix on manual save (Cmd+S / Ctrl+S), or "always" to also fix on auto-save.

Option 2: rumdl.fixOnSave

A simpler toggle that applies all fixes via the LSP server before saving:

{
  "rumdl.fixOnSave": true
}

Option 3: editor.formatOnSave

Uses VS Code's formatting infrastructure to apply rumdl fixes as formatting edits:

{
  "[markdown]": {
    "editor.formatOnSave": true
  }
}

Configuration

The extension uses VS Code's standard configuration system. Open Settings (Cmd/Ctrl + ,) and search for "rumdl" to configure:

Project Configuration

Create a .rumdl.toml file in your project root for project-specific settings:

# Enable/disable specific rules
[rules]
select = ["MD001", "MD003", "MD022"]
ignore = ["MD013", "MD033"]

# Rule-specific configuration
[rules.MD013]
line_length = 120
code_blocks = false

[rules.MD003]
style = "atx"

# File patterns to include/exclude
[files]
include = ["**/*.md", "**/*.markdown"]
exclude = ["node_modules/**", "target/**"]

Supported File Types

The extension automatically activates for these file extensions:

• .md
• .markdown
• .mdown
• .mkd
• .mdx

Performance

rumdl is built for speed:

Rule Compatibility

rumdl supports 97.2% of markdownlint rules:

• ✅ 50+ rules fully implemented
• ✅ Auto-fixes for 40+ rules
• ✅ Custom configuration support
• ✅ Same rule IDs as markdownlint

See the full rule list for details.

Troubleshooting

rumdl not found

If you see "rumdl executable not found":

1. Install rumdl: Follow the installation guide
2. Check PATH: Ensure rumdl is in your system PATH
3. Set custom path: Configure rumdl.server.path in settings

Server not starting

If the server fails to start:

1. Check logs: Use "rumdl: Show client logs" command
2. Verify installation: Run rumdl --version in terminal
3. Restart server: Use "rumdl: Restart Server" command
4. Check configuration: Ensure .rumdl.toml is valid

Performance issues

If linting feels slow:

1. Check file size: Very large files (>1MB) may be slower
2. Exclude patterns: Add exclusions for generated files
3. Reduce rules: Disable unused rules in configuration

Development

Building from Source

# Clone the repository
git clone https://github.com/rumdl/rumdl-vscode.git
cd rumdl-vscode

# Install dependencies
npm install

# Build the extension
npm run compile

# Run in development mode
npm run watch

Testing

# Run linting
npm run lint

Contributing

We welcome contributions! Please check the repository for contribution guidelines.

Reporting Issues

When reporting issues, please include:

1. VS Code version
2. Extension version
3. rumdl version (rumdl --version)
4. Debug information (use "rumdl: Print debug information")
5. Sample Markdown file that reproduces the issue

License

This extension is licensed under the MIT License.

Related Projects

• rumdl - The core Rust-based linter
• markdownlint - The original JavaScript linter
• markdownlint-cli2 - Command-line interface

Changelog

See CHANGELOG.md for release history.

Enjoy lightning-fast Markdown linting with rumdl! ⚡