vale

Syntax-aware prose linter

TLDR

Lint files in current directory

$ vale [path/to/files]

Lint markdown files recursively

$ vale [docs/**/*.md]

Use a specific configuration file

$ vale --config [.vale.ini] [file.md]

Show only errors (ignore warnings and suggestions)

$ vale --minAlertLevel error [file.md]

Output in JSON format

$ vale --output JSON [file.md]

Lint content from stdin

$ echo "[text]" | vale --ext .md

List configured directories

$ vale ls-dirs

Sync styles from configuration

$ vale sync

Vale is a syntax-aware prose linter that brings code-like linting to documentation and prose. It checks writing against customizable style rules for consistency, grammar, and corporate style guides.Vale supports Markdown, AsciiDoc, reStructuredText, HTML, and other markup formats. It can use community style packages (Microsoft, Google, write-good) or custom rules defined in YAML.Configuration is managed through .vale.ini files that specify which styles to use, file patterns to check, and vocabulary exceptions.

PARAMETERS

--config file

Use specified configuration file (.vale.ini).

--ext extension

Assign a file extension to stdin input (e.g., `.md`, `.rst`).

--glob pattern

Only lint files matching the glob pattern.

--filter expr

Filter rules by a CEL-style expression (e.g. `".Level == 'error'"`).

--minAlertLevel level

Minimum alert level: `suggestion`, `warning`, or `error`.

--output format

Output format: `CLI` (default), `JSON`, `line`, or path to a template file.

--no-exit

Always exit with status 0 regardless of errors.

--no-wrap

Do not wrap output lines.

--no-global

Skip loading the global configuration.

--relative

Report paths relative to the current directory.

--sort

Sort output by file path and line number.

--ignore-syntax

Treat all input as plain text (skip syntax-aware parsing).

-v, --version

Display version information.

-h, --help

Display help message.

SUBCOMMANDS

sync

Download and install packages declared in the configuration.

ls-config

Print the active configuration as JSON.

ls-dirs

Print the location of Vale's configuration directories.

ls-metrics file

Print readability and other metrics for the given file.

ls-vars

Print the supported environment variables.

CAVEATS

Vale requires style packages to be installed via vale sync before they can be used. Custom vocabulary (acceptable terms, spelling exceptions) must be configured in the vale configuration. Complex regex-based rules may have performance impact on large documents.

HISTORY

Vale was created by Joseph Kato at Errata AI and first released in 2017. It was designed to provide maintainable, extensible prose linting similar to how code linters work. Written in Go for performance and cross-platform support, Vale has been adopted by many technical documentation teams including GitLab, Grafana, and Linode.