markdownlint

markdownlint is a Node.js static analysis tool and linter for Markdown files that enforces standards and consistency across your documentation. It uses the micromark parser and honors CommonMark specifications while supporting popular GitHub Flavored Markdown extensions.

Key Features:

Comprehensive Rule Set: Over 50 built-in rules covering heading styles, list formatting, line length, whitespace management, and link validation
Format Support: Full CommonMark compliance with GitHub Flavored Markdown, tables, autolinks, and extension support for directives, footnotes, and math
Automatic Fixing: Many rules can automatically repair formatting issues, saving manual effort
Flexible Configuration: Extensive customization through JSON configuration files with rule-specific settings and style presets
Inline Control: HTML comment syntax for enabling/disabling rules within documents ()
Custom Rules: Extensible architecture allowing project-specific linting requirements
Performance Optimized: Fast analysis suitable for large documentation projects

MarkdownLint is run through markdownlint-cli

markdownlint documentation

Version in MegaLinter: 0.45.0
Visit Official Web Site
See How to configure markdownlint rules
- If custom .markdownlint.json config file isn't found, .markdownlint.json will be used
See How to disable markdownlint rules in files
See How to ignore files and directories with markdownlint
See Index of problems detected by markdownlint

Configuration in MegaLinter

Enable markdownlint by adding MARKDOWN_MARKDOWNLINT in ENABLE_LINTERS variable
Disable markdownlint by adding MARKDOWN_MARKDOWNLINT in DISABLE_LINTERS variable

Enable autofixes by adding MARKDOWN_MARKDOWNLINT in APPLY_FIXES variable

Variable	Description	Default value
MARKDOWN_DEFAULT_STYLE	For markdownlint to be active, MARKDOWN_DEFAULT_STYLE must be `markdownlint`	`markdownlint`
MARKDOWN_MARKDOWNLINT_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
MARKDOWN_MARKDOWNLINT_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
MARKDOWN_MARKDOWNLINT_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: `(src\\|lib)`	Include every file
MARKDOWN_MARKDOWNLINT_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: `(test\\|examples)`	Exclude no file
MARKDOWN_MARKDOWNLINT_CLI_LINT_MODE	Override default CLI lint mode - `file`: Calls the linter for each file - `list_of_files`: Call the linter with the list of files as argument - `project`: Call the linter from the root of the project	`list_of_files`
MARKDOWN_MARKDOWNLINT_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".md"]`
MARKDOWN_MARKDOWNLINT_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: `["Dockerfile(-.+)?", "Jenkinsfile"]`	Include every file
MARKDOWN_MARKDOWNLINT_PRE_COMMANDS	List of bash commands to run before the linter	None
MARKDOWN_MARKDOWNLINT_POST_COMMANDS	List of bash commands to run after the linter	None
MARKDOWN_MARKDOWNLINT_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling MARKDOWN_MARKDOWNLINT and its pre/post commands	None
MARKDOWN_MARKDOWNLINT_CONFIG_FILE	markdownlint configuration file nameUse `LINTER_DEFAULT` to let the linter find it	`.markdownlint.json`
MARKDOWN_MARKDOWNLINT_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
MARKDOWN_MARKDOWNLINT_DISABLE_ERRORS	Run linter but consider errors as warnings	`true`
MARKDOWN_MARKDOWNLINT_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
MARKDOWN_MARKDOWNLINT_CLI_EXECUTABLE	Override CLI executable	`['markdownlint']`

IDE Integration

Use markdownlint in your favorite IDE to catch errors before MegaLinter !

IDE	Extension Name	Install
Sublime Text	SublimeLinter-contrib-markdownlint	Visit Web Site
vim	coc-markdownlint	Visit Web Site
Visual Studio Code	vscode-markdownlint

MegaLinter Flavors

This linter is available in the following flavors

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	127
c_cpp	Optimized for pure C/C++ projects	57
cupcake	MegaLinter for the most commonly used languages	88
documentation	MegaLinter for documentation projects	50
dotnet	Optimized for C, C++, C# or VB based projects	65
dotnetweb	Optimized for C, C++, C# or VB based projects with JS/TS	74
formatters	Contains only formatters	18
go	Optimized for GO based projects	52
java	Optimized for JAVA based projects	55
javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	60
php	Optimized for PHP based projects	55
python	Optimized for PYTHON based projects	66
ruby	Optimized for RUBY based projects	51
rust	Optimized for RUST based projects	51
salesforce	Optimized for Salesforce based projects	55
swift	Optimized for SWIFT based projects	51
terraform	Optimized for TERRAFORM based projects	55

Behind the scenes

How are identified applicable files

File extensions: .md

How the linting is performed

markdownlint is called once with the list of files as arguments (list_of_files CLI lint mode)

Example calls

markdownlint myfile.md

markdownlint -c .markdownlint.json myfile.md

markdownlint --fix -c .markdownlint.json myfile.md

Help content

Usage: markdownlint [options] [files|directories|globs...]

MarkdownLint Command Line Interface

Arguments:
  files|directories|globs                    files, directories, and/or globs to lint

Options:
  -V, --version                              output the version number
  -c, --config <configFile>                  configuration file (JSON, JSONC, JS, YAML, or TOML)
  --configPointer <pointer>                  JSON Pointer to object within configuration file (default: "")
  -d, --dot                                  include files/folders with a dot (for example `.github`)
  -f, --fix                                  fix basic errors (does not work with STDIN)
  -i, --ignore <file|directory|glob>         file(s) to ignore/exclude (default: [])
  -j, --json                                 write issues in json format
  -o, --output <outputFile>                  write issues to file (no console)
  -p, --ignore-path <file>                   path to file with ignore pattern(s)
  -q, --quiet                                do not write issues to STDOUT
  -r, --rules <file|directory|glob|package>  include custom rule files (default: [])
  -s, --stdin                                read from STDIN (does not work with files)
  --enable <rules...>                        Enable certain rules, e.g. --enable MD013 MD041 --
  --disable <rules...>                       Disable certain rules, e.g. --disable MD013 MD041 --
  -h, --help                                 display help for command

Installation on mega-linter Docker image

Dockerfile commands :

# renovate: datasource=npm depName=markdownlint-cli
ARG NPM_MARKDOWNLINT_CLI_VERSION=0.45.0

NPM packages (node.js):
- markdownlint-cli@0.45.0