rumdl - An extremely fast Markdown linter, written in Rust

An extremely fast Markdown linter and formatter, written in Rust

| Docs | Rules | Configuration |

Table of Contents

• rumdl - An extremely fast Markdown linter, written in Rust
  • Table of Contents
  • Overview
  • Installation
    • Using Cargo (Rust)
    • Using pip (Python)
    • Download binary
  • Usage
  • Rules
  • Command-line Interface
    • Commands
    • Options
  • Configuration
  • Output Style
    • Output Format
  • Development
    • Prerequisites
    • Building
    • Testing
  • License

Overview

rumdl is a lightning-fast Markdown linter and fixer that helps ensure consistency and best practices in your Markdown files. It offers:

• ⚡️ 10-50x faster than other Markdown linters
• 🔍 50+ lint rules covering common Markdown issues
• 🛠️ Automatic fixing with --fix for most rules
• 📦 Zero dependencies - single binary with no runtime requirements
• 🔧 Highly configurable with TOML-based config files
• 🌐 Multiple installation options - Rust, Python, standalone binaries
• 📏 Modern CLI with detailed error reporting
• 🔄 CI/CD friendly with non-zero exit code on errors

Installation

Choose the installation method that works best for you:

Using Cargo (Rust)

cargo install rumdl

Using pip (Python)

pip install rumdl

Download binary

# Linux/macOS
curl -LsSf https://github.com/user/rumdl/releases/latest/download/rumdl-linux-x86_64.tar.gz | tar xzf - -C /usr/local/bin

# Windows PowerShell
Invoke-WebRequest -Uri "https://github.com/user/rumdl/releases/latest/download/rumdl-windows-x86_64.zip" -OutFile "rumdl.zip"
Expand-Archive -Path "rumdl.zip" -DestinationPath "$env:USERPROFILE\.rumdl"

Usage

Getting started with rumdl is simple:

# Check a single file
rumdl README.md

# Check all Markdown files in current directory and subdirectories
rumdl .

# Automatically fix issues
rumdl --fix README.md

# Create a default configuration file
rumdl init

Common usage examples:

# Check with custom configuration
rumdl --config my-config.toml docs/

# Disable specific rules
rumdl --disable MD013,MD033 README.md

# Enable only specific rules
rumdl --enable MD001,MD003 README.md

# Exclude specific files/directories
rumdl --exclude "node_modules,dist" .

# Include only specific files/directories
rumdl --include "docs/*.md,README.md" .

# Combine include and exclude patterns
rumdl --include "docs/**/*.md" --exclude "docs/temp,docs/drafts" .

Rules

rumdl implements over 50 lint rules for Markdown files. Here are some key rule categories:

For a complete list of rules and their descriptions, see our documentation or run:

rumdl --list-rules

Command-line Interface

rumdl [options] [file or directory...]
rumdl <command> [options]

Commands

• init: Create a default .rumdl.toml configuration file in the current directory

Options

• -c, --config <file>: Use custom configuration file
• -f, --fix: Automatically fix issues where possible
• -l, --list-rules: List all available rules
• -d, --disable <rules>: Disable specific rules (comma-separated)
• -e, --enable <rules>: Enable only specific rules (comma-separated)
• --exclude <patterns>: Exclude specific files or directories (comma-separated glob patterns)
• --include <patterns>: Include only specific files or directories (comma-separated glob patterns)
• --respect-gitignore: Respect .gitignore files when scanning directories
• -v, --verbose: Show detailed output

Configuration

rumdl can be configured using a TOML configuration file. By default, it looks for rumdl.toml or .rumdl.toml in the current directory.

You can create a default configuration file using the init command:

rumdl init

This will create a .rumdl.toml file in the current directory with default settings that you can customize.

Example configuration file:

# Global configuration options
[global]
# List of rules to disable
disable = ["MD013", "MD033"]

# List of rules to enable exclusively (if provided, only these rules will run)
# enable = ["MD001", "MD003", "MD004"]

# List of file/directory patterns to include for linting (if provided, only these will be linted)
include = [
    # Documentation files
    "docs/**/*.md",
    "README.md",
    "CONTRIBUTING.md",
]

# List of file/directory patterns to exclude from linting
exclude = [
    # Common directories to exclude
    ".git",
    ".github",
    "node_modules",
    "vendor",
    "dist",
    "build",

    # Specific files or patterns
    "CHANGELOG.md",
    "LICENSE.md",
    "generated/*.md",
    "**/temp_*.md",
]

# Whether to respect .gitignore files when scanning directories
respect_gitignore = false

# Rule-specific configurations
[MD002]
level = 1  # Expected level for first heading

[MD003]
style = "atx"  # Heading style (atx, atx_closed, setext)

Output Style

rumdl produces clean, colorized output similar to modern linting tools:

README.md:12:1: [MD022] Headings should be surrounded by blank lines [*]
README.md:24:5: [MD037] Spaces inside emphasis markers: "* incorrect *" [*]
README.md:31:76: [MD013] Line length exceeds 80 characters
README.md:42:3: [MD010] Hard tabs found, use spaces instead [*]

When running with --fix, rumdl shows which issues were fixed:

README.md:12:1: [MD022] Headings should be surrounded by blank lines [fixed]
README.md:24:5: [MD037] Spaces inside emphasis markers: "* incorrect *" [fixed]
README.md:42:3: [MD010] Hard tabs found, use spaces instead [fixed]

Fixed 3 issues in 1 file

For a more detailed view, use the --verbose option:

✓ No issues found in CONTRIBUTING.md
README.md:12:1: [MD022] Headings should be surrounded by blank lines [*]
README.md:24:5: [MD037] Spaces inside emphasis markers: "* incorrect *" [*]
README.md:42:3: [MD010] Hard tabs found, use spaces instead [*]

Found 3 issues in 1 file (2 files checked)
Run with `--fix` to automatically fix issues

Output Format

rumdl uses a consistent output format for all issues:

{file}:{line}:{column}: [{rule*id}] {message} [{fix*indicator}]

The output is colorized by default:

• Filenames appear in blue and underlined
• Line and column numbers appear in cyan
• Rule IDs appear in yellow
• Error messages appear in white
• Fixable issues are marked with [*] in green
• Fixed issues are marked with [fixed] in green

Development

Prerequisites

• Rust 1.70 or higher
• Make (for development commands)

Building

make build

Testing

make test

License

MIT License