mkdlint

A fast Markdown linter written in Rust, inspired by markdownlint.

Features

• 54 lint rules (MD001-MD060) enforcing Markdown best practices
• Automatic fixing for 27 rules with --fix flag
• Rich error display with source context and colored underlines pointing to errors
• Multiple output formats — text (default), JSON, or SARIF
• Configuration via JSON, YAML, or TOML files with auto-discovery
• High performance — parallel file processing with optimized rules
• Library + CLI — use as a Rust crate or standalone command-line tool

Installation

From source

cargo install --path .

As a library dependency

[dependencies]
mkdlint = { version = "0.1", default-features = false }

CLI Usage

Basic Commands

# Lint files
mkdlint README.md docs/*.md

# Lint with auto-fix
mkdlint --fix README.md

# Lint a directory recursively
mkdlint docs/

# Lint from stdin
cat README.md | mkdlint --stdin

# List all available rules with descriptions
mkdlint --list-rules

Configuration Management

# Initialize a new config file with defaults
mkdlint init

# Initialize with custom path and format
mkdlint init --output .mkdlint.yaml --format yaml

# Use a specific config file
mkdlint --config .markdownlint.json README.md

# Enable/disable specific rules on the fly
mkdlint --enable MD001 --disable MD013 README.md

# Combine multiple rule overrides
mkdlint --config base.json --enable MD001 --disable MD033 docs/

Output Control

# Output in JSON format (machine-readable)
mkdlint --output-format json README.md

# Output in SARIF format (for CI/CD integration)
mkdlint --output-format sarif README.md

# Quiet mode - only show filenames with errors
mkdlint --quiet docs/

# Verbose mode - show detailed error statistics
mkdlint --verbose docs/

# Disable colored output (for CI environments)
mkdlint --no-color README.md

Advanced Usage

# Ignore specific files/patterns
mkdlint --ignore "**/node_modules/**" --ignore "**/.git/**" .

# Combine multiple options
mkdlint --config .mkdlint.json \
       --ignore "build/**" \
       --ignore "dist/**" \
       --fix \
       --verbose \
       .

# Fix with specific rules disabled
mkdlint --fix --disable MD013 --disable MD033 docs/

# Stdin with fix output to stdout
cat README.md | mkdlint --stdin --fix > README_fixed.md

Example Output

mkdlint provides rich error display with source context:

README.md: 42: MD009/no-trailing-spaces Trailing spaces [Expected: 0; Actual: 3]
  42 |
  42 |  This line has trailing spaces
     |                               ^^^

README.md: 58: MD034/no-bare-urls Bare URL used
  58 |
  58 |  Visit https://example.com for more info.
     |        ^^^^^^^^^^^^^^^^^^^

Commands

Options

Library Usage

use mkdlint::{lint_sync, apply_fixes, LintOptions};

let options = LintOptions {
    files: vec!["README.md".to_string()],
    ..Default::default()
};

let results = lint_sync(&options).unwrap();
for (file, errors) in results.iter() {
    for error in errors {
        println!("{}: {}", file, error);
    }
}

Auto-fixing

use mkdlint::{lint_sync, apply_fixes, LintOptions};
use std::collections::HashMap;

let content = "# Title\n\nSome text   \n";
let mut strings = HashMap::new();
strings.insert("test.md".to_string(), content.to_string());

let options = LintOptions { strings, ..Default::default() };
let results = lint_sync(&options).unwrap();

if let Some(errors) = results.get("test.md") {
    let fixed = apply_fixes(content, errors);
    println!("{}", fixed); // trailing whitespace removed
}

Configuration

Create a .markdownlint.json (or .yaml / .toml) file:

{
  "default": true,
  "MD013": { "line_length": 120 },
  "MD033": false
}

Rules can be enabled/disabled by name ("MD013") or alias ("line-length"). Pass a boolean to enable/disable, or an object to configure options.

Rules

Bold entries indicate auto-fix added in v0.2.0. Bold+Italic entries are new in v0.3.0.

License

Apache-2.0